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general description the max15301 is a full-featured, highly efficient, digital point-of-load (pol) controller with advanced power man - agement and telemetry features. unlike pid-based digital power regulators, the max15301 uses maxims patented intune? automatically compensated, state-space control algorithm. the intune control law is valid for both the small- and large-signal response and accounts for duty- cycle saturation effects. these capabilities result in fast loop transient response and reduce the number of output capacitors compared to competing digital controllers. the max15301 includes multiple features to optimize efficiency. an internal switch babybuck? regulator gen - erates the gate drive and the internal bias supplies for the controller with low power loss. an advanced, high- efficiency mosfet gate driver has adjustable nonoverlap timing and load-variable gate-drive voltage to minimize switching losses over the full range of voltage, current, and temperature. the max15301 was designed for end-customers design environment. an on-board pmbus?-compliant serial bus interface enables communication with a supervisory con - troller for monitoring and fault management. a full suite of power management features eliminates the need for complicated and expensive sequencing and monitoring ics. basic dc-dc conversion operation can be set up via pin strapping and does not require user configura - tion firmware. this allows for rapid development of the power-supply subsystem before board-level systems engineering is completed. maxim provides support hard - ware and software for configuring the max15301. the max15301 is available in a 32-lead, 5mm x 5mm tqfn package and operates over the -40c to +85c temperature range. features intune automatic compensation ensures stability while optimizing transient performance state-space compensation results in fast transient response with reduced output capacitance differential remote voltage sensing enables 1% v out accuracy over temperature (-40c to +85c) pmbus interface for configuration, control, and monitoring supports voltage positioning high output 2a/4a mosfet driver ? adjustable nonoverlap timing ? variable gate-drive voltage wide input range of 4.5v to 14v efficient on-chip babybuck regulator for self-bias output voltage range from 0.5v to 5.25v startup into a prebiased output configurable soft-start and soft-stop time fixed-frequency operation and synchronization flexible sequencing and fault management pin-strappable configuration ? output voltage, smbus address, switching frequency, current limit out-of-the-box operation enables fast prototyping applications servers storage systems routers/switches base-station equipment power modules ordering information and typical operating circuit appear at end of data sheet. for related parts and recommended products to use with this part, refer to www.maximintegrated.com/max15301.related . intune and babybuck are trademarks of maxim integrated products, inc. pmbus is a trademark of smif, inc. maxim patents apply: 7498781, 7880454, 7696736, 7746048, 7466254, 798613, 7498781, 8,120,401, 8,014,879. this product is subject to a license from power-one, inc., relat - ed to digital power technology patents owned by power-one, inc. this license does not extend to merchant market stand- alone power-supply products. max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry 19-6267; rev 4; 11/13 evaluation kit available downloaded from: http:///
tqfn junction-to-ambient thermal resistance ( ja ) .......... 29c/w junction-to-case thermal resistance ( jc ) .................. 1.7c/w (note 1) insns to sgnd .................................................... -0.3v to +14v lxsns to sgnd ...................................................... -2v to +14v lxsns (pulse < 10ns) to sgnd .............................. -2v to +20v outp, outn, dcrp, dcrn to sgnd ................ -0.3v to +5.5v pwr to pgnd ....................................................... -0.3v to +18v hld to sgnd .......................................................... -0.3v to +4v 3p3 to sgnd ................................. -0.3v to the minimum of +4v or (v gdrv + 0.3v) gdrv to sgnd ........................... -0.3v to the minimum of +12v or (v pwr + 0.3v) lx to pgnd ........ -2v to the minimum of +26v or (v bst + 0.3v) dl to pgnd ......................................... -0.3v to (v gdrv + 0.3v) lbi to pgnd ........................................... -0.3v to (v pwr + 0.3v) lbo to pgnd ........................... (v 3p3 - 0.3v) to (v gdrv + 0.3v) dh to pgnd ................................. (v lx - 0.3v) to (v bst + 0.3v) bst to lx .............................................................. -0.3v to +12v bst to pgnd ........................................................ -0.3v to +26v bst to gdrv ........................................................ -0.3v to +26v 1p8 to dgnd ....................................................... -0.3v to +2.2v cio, set, pg, addr0, addr1, sync, tempx, salrt to dgnd .............................................. -0.3v to +4v en, scl, sda to dgnd ......................................... -0.3v to +4v pgnd to sgnd .................................................... -0.3v to +0.3v dgnd to sgnd ................................................... -0.3v to +0.3v electrostatic discharge (esd) rating human body model (hbm) ......................................... 3500v machine model .............................................................. 200v junction temperature ...................................................... +125c operating temperature range ........................... -40c to +85c continuous power dissipation (t a = +70c) tqfn (derate 34.5mw/c above +70c) ..................2758mw storage temperature range ............................ -65c to +150c lead temperature (soldering, 10s) ................................. +300c soldering temperature (reflow) ....................................... +260c (all settings = factory default, v pwr = v insns = 12v, v sgnd = v dgnd = v pgnd = 0v, v out = 1.2v, f sw = 600khz. specifications are for t a = t j = -40 c to +85 c, typical values are at t a = t j = +25 c. see the typical operating circuit , unless otherwise noted.)(note 2) parameter symbol conditions min typ max units input supply input voltage range v pwr 4.5 14 v input supply current i pwr babybuck bias supply, driver not switching 10 ma linear mode bias supply, driver not switching 24 50 input overvoltage lockout threshold v ovlo(pwr) input rising 14.3 15.2 16.0 v input undervoltage lockout threshold v uvlo(pwr) rising edge 3.8 4.1 4.4 v hysteresis 0.24 bias regulators 3p3 output voltage v 3p3 i load(3p3) = 0ma 3.3 v 1p8 output voltage v 1p8 i load(1p8) = 0ma 1.80 v note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial . absolute maximum ratings stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. package thermal characteristicselectrical characteristics max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 2 downloaded from: http:///
(all settings = factory default, v pwr = v insns = 12v, v sgnd = v dgnd = v pgnd = 0v, v out = 1.2v, f sw = 600khz. specifications are for t a = t j = -40 c to +85 c, typical values are at t a = t j = +25 c. see the typical operating circuit , unless otherwise noted.)(note 2) parameter symbol conditions min typ max units startup/shutdown timing firmware initialization t 1 from v in > v uvlo(pwr) , until ready to enable (figure 2) 25 ms minimum t on_delay t 2 (figure 2, note 4) 1 ms turn-on rise time t 3 (figure 2, note 4) 1 ms adaptive tuning time t 4 from v out = v out command to assertion of power good (pg) (figure 2) 12 ms output voltage output voltage range v out measured from outp to outn (notes 4 and 5) 0.5 5.25 v lx bias current i lx not switching, current out of device pin 200 a duty-cycle range (notes 3 and 4) 5 95 % regulation set-point accuracy t a = +25c, i out 20a (notes 4, 8, 9) -0.5 +0.5 % -40c t a +85c (notes 4, 8, 9) -1 +1 v out sense bias current i outp current lowing into outp 50 a i outn current lowing out of outn 35 a dcr sense bias current i dcrp current lowing into dcr, v dcrp - v dcrn = 150mv 120 na i dcrn 4 a pwm clock (note 4) switching frequency range f sw 300 1000 khz switching frequency set-point accuracy t a = +25c -5 +5 % -10 +10 external clock to sync frequency range f sync 300 1000 khz external clock to sync duty cycle d extclk 40 60 % sync frequency drift tolerance from nominal lock frequency (note 6) -10 +10 % protection (note 4)current-sense common- mode voltage v isp , v isn -0.1 +5.5 v overcurrent fault threshold accuracy t a = +25c, exclusive of sensor error 3 % output overvoltage fault threshold output rising 115 % v out output undervoltage fault threshold output falling 85 % v out electrical characteristics (continued) max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 3 downloaded from: http:///
(all settings = factory default, v pwr = v insns = 12v, v sgnd = v dgnd = v pgnd = 0v, v out = 1.2v, f sw = 600khz. specifications are for t a = t j = -40 c to +85 c, typical values are at t a = t j = +25 c. see the typical operating circuit , unless otherwise noted.)(note 2) parameter symbol conditions min typ max units thermal shutdown threshold accuracy 20 c thermal shutdown hysteresis 20 c power-good threshold v out rising 90 % v out v out falling 85 power management (note 4) startup/shutdown timing firmware initialization t 1 from v in > v uvlo(pwr) , until ready to enable (figure 2) 25 ms ton_delay, toff_delay range t 2 minimum delay (figure 2, note 4) 1 ms maximum delay (figure 2, note 4) 145 ton_delay, toff delay resolution delay timing step size 0.6 ms ton_delay, toff delay command accuracy command value sent vs. readback 0.3 ms ton_delay, toff delay timing accuracy command readback value vs. actual delay time 0.8 ms ton_rise, toff_fall range t 3 minimum (figure 2, note 4) 1 ms maximum (figure 2, note 4) 255 x t rr ton_rise, toff_fall resolution t rr ramp timing step size (varies with vout_command) 0.4 -1.0 ms ton_rise, toff_fall command accuracy command value sent vs. readback 0.5 ms ton_rise, toff_fall timing accuracy command readback value vs. actual ramp duration 10 s adaptive tuning time t 4 from end of soft-start ramp to pg assertion (varies with frequency_switch (figure 2) 12 ms tracking error 200mv < v in < (v out_set - 200mv) (note 7) -100 +100 temperature measurement accuracy external 5 c internal 5 digital i/o power-good logic-high leakage current open-drain output mode, open-drain connected to 5.5v, v 3p3 = 3.3v 10 a output logic-high cmos mode, i source = 4ma v 3p3 - 0.4 v 3p3 v electrical characteristics (continued) max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 4 downloaded from: http:///
(all settings = factory default, v pwr = v insns = 12v, v sgnd = v dgnd = v pgnd = 0v, v out = 1.2v, f sw = 600khz. specifications are for t a = t j = -40 c to +85 c, typical values are at t a = t j = +25 c. see the typical operating circuit , unless otherwise noted.)(note 2) parameter symbol conditions min typ max output logic-low i sink = 4ma 0.4 v input bias current -1 +1 a rise/fall slew rate c load = 15pf 2 ns en, sync input-logic low voltage input voltage falling 0.8 v en, sync input-logic high voltage input voltage rising 2 v en, sync input leakage current -10 +10 a smbus (note 4) sda, scl input logic-low voltage input voltage falling 0.8 v sda, scl input logic-high voltage input voltage rising 2 v sda, scl, salrt logic- high leakage current v scl , v sda = 0v, and v salrt tested at 0v and 3.3v 10 a sda, scl, salrt logic-low output voltage i sink = 4ma 0.4 v pmbus operating frequency f smb 400 khz bus free time (stop - start) t buf 1.3 s start condition hold time from scl t hd:sta 0.6 s start condition setup time from scl t su:sta 0.6 s stop condition setup time from scl t su:sto 0.6 s sda hold time from scl t hd:dat 300 ns sda setup time from scl t su:dat 100 ns scl low period t low 1.3 s scl high period t high 0.6 s driver bias regulator gdrv output voltage range v gdrv gctrldac = 0 5.2 v gctrldac = 15 8.7 gdrv undervoltage lockout v gdrvuvlo gdrv falling, 200mv (typ) hysteresis 3.5 3.75 v lbi, lbo current limit 0.7 a electrical characteristics (continued) max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 5 downloaded from: http:///
(all settings = factory default, v pwr = v insns = 12v, v sgnd = v dgnd = v pgnd = 0v, v out = 1.2v, f sw = 600khz. specifications are for t a = t j = -40 c to +85 c, typical values are at t a = t j = +25 c. see the typical operating circuit , unless otherwise noted.)(note 2) note 2: limits are 100% production tested at t a = +25c. maximum and minimum limits over temperature are guaranteed through correlation using statistical quality control (sqc) methods. typical values are expressed as factory-default values also for configurable specifications within a range. note 3: can go to 100% during a transient. note 4: design guaranteed by bench characterization. limits are not production tested. note 5: the settable output voltage range is 0.6v to 5.0v. this range expands to 0.5v to 5.25v when the voltage margining function is enabled. note 6: once the max15301 locks onto an external synchronizing clock, the tolerance on the capture range is 10%. note 7: see the voltage tracking section. note 8: excluding tracking mode. note 9: voltage regulation accuracy is power-stage dependent; adherence to all data sheet design recommendations is required to achieve specified accuracy. parameter symbol conditions min typ max units high-side driver driver source current i dh_source v pwr = 12v, v dh = 0v, 3.0nf load 2 a driver sink current i dh_sink v pwr = 12v, v dh = 0v, 3.0nf load 4 a dh driver on-resistance (sourcing) r on(dh) v pwr = 12v, v bst - v lx forced to 5v 1 ? dh driver on-resistance (sinking) r on(dh) v pwr = 12v, v bst - v lx forced to 5v 0.4 ? low-side driver driver source current i dl_source v pwr = 12v, v dl = 0v, 5.0nf load 2 a driver sink current i dl_sink v pwr = 12v, v dl = 5v, 5.0nf load 4 a dl driver on-resistance (sourcing) r on(dl) v pwr = 12v, v lx - v pgnd forced to 5v 1 ? dl driver on-resistance (sinking) r on(dl) v pwr = 12v, v lx - v pgnd forced to 5v 0.4 ? driver timing and resistance dl transition time t f_dl falling, 5.0nf load, v gdrv = 5v 10 ns t r_dl rising, 5.0nf load, v gdrv = 5v 15 dh transition time t f_dh falling, 3.0nf load, v gdrv = 5v 8 ns t r_dh rising, 3.0nf load, v gdrv = 5v 10 dh driver pulldown resistance r pd(dh) not switching, v en = 0v 100 300 k? dl driver pulldown resistance r pd(dl) not switching, v en = 0v 100 300 k? boost on-resistance r on(bst) v gdrv = 5v, v dh = v lx = v pgnd (pulldown state), i bst = 10ma 1.5 ? thermal protection gate-driver thermal shutdown threshold t shdn hysteresis = 20c 150 c electrical characteristics (continued) max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 6 downloaded from: http:///
(t a = +25c, v in = 12v, v out = 1.2v, f sw = 600khz, unless otherwise noted. see the typical operating circuit and application 1 in table 8). babybuck efficiency gain (v in = 12v, v out = 1.2v, 500khz) max15301 toc03 load current (a) efficiency (%) 25 20 15 10 5 82.0 83.0 84.0 85.0 86.0 87.0 88.0 89.0 90.0 91.0 92.0 93.0 94.0 95.080.0 81.0 0 30 ldo mode babybuck startup max15301 toc05 4ms/div v out pg en v in 500mv/div5v/div 5v/div 10v/div variable gate-drive efficiency gain max15301 toc01 load current (a) efficiency (%) 40 35 30 25 20 15 10 5 77.5 80.0 82.5 85.0 87.5 90.075.0 0 45 5.0v drive variable gate drive 8.5v drive efficiency vs. load (v in = 12v, 600khz) max15301 toc04 i out (a) efficiency (%) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 10 20 30 40 50 60 70 80 90 100 0 0 1.22.5 3.3 v out (v) shutdown max15301 toc06 4ms/div v out pg en v in 500mv/div5v/div 5v/div 10v/div gdrv voltage vs. gctrldac setting max15301 toc02 gctrldac value v gdrv (v) 13 12 11 10 9 8 7 6 5 4 3 2 1 5 6 7 8 9 10 4 0 1514 typical operating characteristics max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry maxim integrated 7 www.maximintegrated.com downloaded from: http:///
pin name function 1 sync external switching frequency synchronization input. connect a resistor between sync and sgnd to set the switching frequency of the dc-dc converter (see table 2). the max15301 can also synchronize with an external clock applied at sync. 2 addr0 smbus address select input 0. used with addr1 to assign a unique smbus address to the device. 3 set output voltage set input. connect a resistor between set and sgnd to set the output voltage. shorting this pin to ground selects tracking mode (see table 1). 4 addr1 smbus address select input 1. used with addr0 to assign a unique smbus address to the device and set the current limit for max15301. 5 dgnd digital ground. connect to dgnd and pgnd using short, wide pcb traces. 6 1p8 internal 1.8v regulator output. 1p8 is the supply rail for the internal digital circuitry. bypass 1p8 to dgnd with a 10f ceramic capacitor. this pin may not be used to power any circuitry external to the max15301. 7 tempx connection for the external temperature sensor. connect an npn transistor junction from tempx to sgnd to measure the temperature at any point on the pcb. place a 100pf ceramic capacitor in parallel with the temperature sense junction. 8 cio conigurable input/output pin. this is a voltage-tracking input when set is connected to sgnd to sele ct tracking mode. cio must be grounded when not in tracking mode. max15301 tqfn top view 2930 28 27 1211 13 addr0addr1 dgnd 1p8 tempx 14 sync lbolbi pgnd 3p3dl gdrv 1 2 i.c. 4 5 6 7 23 24 22 20 19 18 i.c. dcrp lxsns insns en sda ep sgnd set pwr 3 21 31 10 dcrn scl 32 9 pg salrt + outp 26 15 dh outn 25 16 lx cio bst 8 17 3p3 pin description pin coniguration max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 8 downloaded from: http:///
pin name function 9 salrt smbus alert. interrupt to the smbus master. open-drain output that pulls low when smbus interaction is required. 10 scl smbus clock input 11 sda smbus data input/output 12 en enable input. do not leave unconnected. by default, driving en high enables output regulation, and driving en low disables output regulation. 13 insns powertrain input rail sense. monitors the input supply of the dc-dc converter. connect a series 2k? resistor between input rail and insns pin. 14 lxsns switching node sense input. connect a series 2k? resistor between switching node and lxsns pin. 15 dh high-side mosfet gate drive 16 lx switching node. connect directly to the high-side of the output inductor. 17 bst bootstrap capacitor connection. connect a 0.22f ceramic capacitor between bst and the switching node. 18 gdrv gate-driver supply. bypass gdrv to pgnd with a 2.2f ceramic capacitor. 19 dl low-side mosfet gate drive 20 pgnd power ground. connect to sgnd and dgnd using short wide pcb traces. 21 lbi babybuck switching node 1. see the babybuck regulator section for conigurations. 22 pwr power-supply input. connect to a power-supply input. bypass to ground with a 1f ceramic capacitor. 23 lbo babybuck switching node 2. see the babybuck regulator section for conigurations. 24, 25 3p3 internal 3.3v regulator output. 3p3 is the supply rail for the internal analog circuitry. bypass 3p3 to sgnd with a 4.7f ceramic capacitor. this pin may not be used to power any circuitry external to the max15301. 26 outn output voltage differential sense negative input. connect to ground at the load. 27 outp output voltage differential sense positive input. connect to the output at the load. 28, 29 i.c. internally connected. connect directly to ground near the max15301. 30 dcrp output current differential sense positive input. connect to the inductor or current-sense element positive side through an appropriate ilter network. 31 dcrn output current differential sense negative input. connect to the inductor or current-sense element negative side. 32 pg open-drain power-good indicator. pg asserts high when soft-start is complete, the voltage has reached regulation, after a successful intune calibration is completed. ep sgnd exposed pad and analog ground. the ep serves two purposes: it is both the analog ground of the device and a conduit for heat transfer. connect to a large ground plane to maximize thermal performance. see the pcb layout guidelines section. pin description (continued) max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 9 downloaded from: http:///
detailed description the max15301 is an innovative, pmbus-compliant, mixed-signal power management ic with a built-in high-performance digital pwm controller for pol appli - cations. the max15301 is based on maxims intune automatically compensated digital pwm control loop. the max15301 has optimal partitioning of the digital power management and the digital power conversion domains to minimize startup times and reduce bias current. the max15301 supports over 80 standard and manufacturer-specific pmbus commands. the max15301 uses adaptive compensation techniques to handle a broad range of timing, voltage, current, tem - perature, and external component parameter variations. efficiency optimization techniques further enhance the performance of the max15301, including adjustable nonoverlap timing, load-variable gate-drive voltage, and switch-mode babybuck bias regulators for biasing the internal circuit blocks and the mosfet gate drive. the max15301 features integrated power conversion to self-bias its digital, analog, and driver blocks from a single input supply (v pwr ). the max15301 relies on mixed- signal design techniques to control the power system efficiently and precisely. it does not require any software to configure or initialize the device. in addition, functions can be monitored and configured through the smbus interface using standard pmbus commands resulting in ease of design and flexibility. the control loop is separated from the housekeeping, power monitoring, and fault management blocks. control loop parameters are stored in an on-chip nonvolatile flash memory. an internal microcontroller enables monitoring operating conditions using the smbus interface. the dpwm control loop is implemented using dedicated state machines, there is no dsp or mcu in the control loop. this partition allows for architecture that minimizes power consumption while optimizing performance. max15301 aux adc fb adc pmbus mcu flash hssp soft-start ilim nlss compensator en scl sda salrt dgnd sgnd ep io addr0 insns lxsns addr1 set cio sync pg tempx driver fault processor dpwm mux lx detect osc/ sync thermal protection 1.8v reg pgnddcrp dcrn outp outn dl sgnd lx dh bst gdrv lbo 1p8lbi 3p3pwr ram sido reg functional diagram max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 10 downloaded from: http:///
the functional diagram shows the controller implemen - tation using a digital state space compensator (model predictive) controller, a microcontroller unit (mcu), a digi - tal pulse-width modulator (dpwm), a pll-based master timing generator, and a pmbus serial communication port. state-space controller and dpwm the max15301 uses a digital pulse-width modulation (dpwm) control scheme to regulate the output voltage. traditional pwm regulators (both analog and digital) use classical control methods for dc-dc converters based on linear models of a discrete time nature and root locus, bode and nyquist plots. these linear time-invariant approximations work well for small signals. however, when large transients cause duty-cycle saturation, the performance of the closed loop can be degraded (larger overshoots) and the output transients will be slower (large settling times). tighter regulation performance dur - ing these disturbances is becoming a requirement. the max15301 addresses the issue by using model-predic - tive-based feedback design to compensate the dpwm. the max15301 automatically constructs a state-space model (state estimator) of the control plant ( figure 1 ). the internal model gives access to state control variables that are otherwise unavailable. the state control variables are used to set the proper control values. for a given input to output step-down ratio and pwm switching frequency the max15301 sets the compensation coefficients for that application. upon output enable, or in response to a pmbus command, the max15301 will perform the intune calibration. during this calibration several powertrain parameter values are measured and the extracted param - eters are used to create the internal model to optimize the bandwidth and transient response of the converter. the state-space compensator block generates the duty- cycle command for the dpwm block. the dpwm block generates the required pwm outputs for the driver. the state-space controller block also contains a digital-to- analog converter that adjusts the gate-drive voltage. the gate-drive voltage can be set using a pmbus command (manufacturer specific) to a value between 5v and 8.5v to improve the power-supply efficiency. babybuck regulator the max15301 has an internal babybuck bias regula - tor circuit to generate both the gate-drive voltage supply and the internal digital supply to power the controller. the babybuck bias regulator is an internal two output switching regulator that uses a small (1008-size), low- cost inductor. if the user is not concerned with optimizing operating efficiency, the inductor can be omitted from the designs (connect the lbi pin to the pwr pin through a 100k resistor). in this configuration, the bias regulator operates as a linear regulator (ldo). if an external gate- drive voltage is available, the lbi pin can be connected to v in through a 2k resistor and the gdrv pin can be connected to the external source. figure 1. state-space controller concept ? driver v in a/d dpwm 1/x state estimator load compensator max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 11 downloaded from: http:///
external temperature sense a temperature sensor input pin (tempx) automatically performs a temperature measurement using the base- emitter junction of a standard 2n3904 transistor. when this device is connected to the tempx pin, the max15301 uses the external temperature information for temperature fault and current measurement temperature compensa - tion (tempco). if the external temperature measurement feature is not required, connect tempx to ground. in this case, the max15301 ignores the invalid external reading and uses the internal signal for temperature compensa - tion and thermal fault protection. the temperature measurements can be read using the pmbus commands read_temperature_1 and read_temperature_2 for internal and external tem - perature, respectively. regulation and monitoring functions the max15301 improves the reliability of the system it powers with multiple circuits that protect the regulator and the load from unexpected system faults. the max15301 continuously monitors the input voltage, output voltage and current, internal and external temperatures. the max15301 can be configured to provide alerts for specific conditions of the monitored parameters. the thresholds and responses for these parameters have factory-default values but can also be configured through the pmbus interface. the status of the power supply can be queried any time by a pmbus master. regulator parameters key operating parameters in the max15301, such as output voltage, switching frequency, and current-sense resistence, can be configured using resistors. this pro - vides flexibility for the user while ensuring that the device will have a well-defined out-of-the-box operational state. the pin configurations are only sampled when power is first applied (the max15301 ignores changes to resistor settings after power-up). from this initial operating state, it is possible for the user to change the parameters using pmbus commands. these changes can be stored in non - volatile memory, and the device will subsequently power up in the newly stored configuration state. however, it is recommended that the pin-strap or resistor settings always be applied with values chosen to provide a safe initial behavior prior to pmbus configuration. pin-strap settings are programmed by connecting a resis - tor from the appropriate max15301 pins to sgnd. the max15301 reads the resistance at startup and sets com - mand parameters per the tables in the following detail sec - tions. note that the external parts count can be reduced in some cases by floating or grounding the configuration pins. output voltage selection the set pin is used to establish the initial output voltage; it can be pin strapped high or low, or connected to sgnd through a resistor, to select the output voltage as shown in table 1 . note that the set pin is read once at power-up and cannot be used to change the output voltage after that time. if the desired output voltage is not included in table 1 , use a resistor to set the initial approximate output voltage, and then send vout_command to set the exact desired output voltage. the output voltage can be set to any voltage between 0.5v and 5.25v, including margining, provided the input voltage to the dc-dc converter (v pwr ) is higher than the output voltage by an amount that conforms to the maximum duty cycle specification. table 1. output voltage setting using pin- resistor setting r set (k?) output voltage (v) 0 to 4.3 track mode 5 to 5.2 0.6 6.1 to 6.3 0.7 7 to 7.3 0.75 8.1 to 8.4 0.8 9.4 to 9.7 0.85 10.8 to 11.2 0.9 12.5 to 12.9 0.95 14.5 to 14.9 1 17.6 to 18 1.05 21.2 to 21.8 1.1 25.8 to 26.4 1.2 31.2 to 32 1.5 37.9 to 38.7 1.8 43.7 to 44.7 2.5 50.5 to 51.7 3.3 58.4 to 59.6 5 67.4 to open 0 max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 12 downloaded from: http:///
setting switching frequency the switching frequency can be adjusted from 300khz to 1mhz with an external resistor from sync to sgnd per table 3 , or by sending the pmbus frequency_switch command. as a guideline, lower frequencies can be used to improve efficiency, while higher frequencies can be selected to reduce the physical size and value of the external filter inductor and capacitors. external synchronization the max15301 may be configured to synchronize with an external clock to eliminate beat noise on the input and output voltage lines or to minimize input voltage ripple. synchronization is achieved by connecting a clock source to the sync pin. the incoming clock signal must be in the 300khz to 1mhz range and must be stable (see the sync frequency drift tolerance specification in the electrical characteristics table). the max15301 synchronizes to the rising edge of the clock after the ic is enabled. in the event of a loss of the external clock signal during normal operation after successful synchronization with the external clock, the max15301 automatically switches at the frequency programmed into the pmbus commands frequency_ switch variable. if an external clock is present at power- on, the ic writes 300khz into frequency_switch. if the clock is still present at enable, the ic overwrites frequency_switch with the actual clock frequency. if a clock is not present at power-on, the max15301 reads the pinstrap resistor value and writes the frequency into frequency_switch per table 5 . if an external clock is applied to sync after power on but before enable, the ic overwrites frequency_switch with the external clock frequency at enable. if an external clock is not applied prior to the ic being enabled, the ic keeps the originally programmed frequency_switch value. for proper synchronization, the external clock may be applied prior to applying power to the ic but must be applied prior to enabling the ic. the external clock frequency should not be changed after the ic is enabled. the max15301 supports interleaving with an external sync input. phase delay between the rising edge of the sync clock signal and the center of the pwm pulse is set to a default value determined by the 7-bit smbus address as shown in table 2 . the phase delay can also be changed by sending the pmbus interleave command while the output is disabled. ilim and smbus address selection the addr0 and addr1 pins are used in combination to set both the current-sense resistance and the smbus address as listed in table 4a and table 4b . note that smbus specification recommends against using the shaded addresses. table 3. switching frequency resistor settings (sync) table 2. interleave settings smbus address phase delay () xxxx000b 0 xxxx001b 60 xxxx010b 120 xxxx011b 180 xxxx100b 240 xxxx101b 300 xxxx110b 90 xxxx111b 270 r sync (k?) switching frequency (khz) 0 to 4.3 575 5 to 5.2 300 6.1 to 6.3 350 7 to 7.3 400 8.1 to 8.4 450 9.4 to 9.7 500 10.8 to 11.2 550 12.5 to 12.9 600 14.5 to 14.9 650 17.6 to 18 700 21.2 to 21.8 750 25.8 to 26.4 800 31.2 to 32 850 37.9 to 38.7 900 43.7 to 44.7 950 50.5 to 51.7 1000 58.4 to open 575 max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 13 downloaded from: http:///
table 4a. smbus address set by addr0, addr1 resistor connections table 4b. iout_cal_gain set by addr1 resistor connection note: the smbus specification recommends against using the shaded addresses. dcr r addr1 (k?) 0.4m w ? 0 to 4.3 5 to 5.2 6.1 to 6.3 7 to 7.3 8.1 to 8.4 0.8m w ? 9.4 to 9.7 10.8 to 11.2 12.5 to 12.9 14.5 to 14.9 17.6 to 18 1.2m w ? 21.2 to 21.8 25.8 to 26.4 31.2 to 32 37.9 to 38.7 43.7 to 44.7 1.6m w ? 50.5 to 51.7 58.4 to 59.6 67.4 to 68.8 85.7 to 87.5 113.8 to 116.2 2.0m w ? 138.6 to 141.4 167.3 to 170.7 202.9 to 207.1 234.6 to 239.4 271.2 to open r addr0 (k?) smbus 7-bit device address 0 to 4.3 0x0a 0x22 0x3a 0x52 0x6a 5 to 5.2 0x0b 0x23 0x3b 0x53 0x6b 6.1 to 6.3 0x0c 0x24 0x3c 0x54 0x6c 7 to 7.3 0x0d 0x25 0x3d 0x55 0x6d 8.1 to 8.4 0x0e 0x26 0x3e 0x56 0x6e 9.4 to 9.7 0x0f 0x27 0x3f 0x57 0x6f 10.8 to 11.2 0x10 0x28 0x40 0x58 0x70 12.5 to 12.9 0x11 0x29 0x41 0x59 0x71 14.5 to 14.9 0x12 0x2a 0x42 0x5a 0x72 17.6 to 18 0x13 0x2b 0x43 0x5b 0x73 21.2 to 21.8 0x14 0x2c 0x44 0x5c 0x74 25.8 to 26.4 0x15 0x2d 0x45 0x5d 0x75 31.2 to 32 0x16 0x2e 0x46 0x5e 0x76 37.9 to 38.7 0x17 0x2f 0x47 0x5f 0x77 43.7 to 44.7 0x18 0x30 0x48 0x60 0x78 50.5 to 51.7 0x19 0x31 0x49 0x61 0x79 58.4 to 59.6 0x1a 0x32 0x4a 0x62 0x7a 67.4 to 68.8 0x1b 0x33 0x4b 0x63 0x7b 85.7 to 87.5 0x1c 0x34 0x4c 0x64 0x7c 113.8 to 116.2 0x1d 0x35 0x4d 0x65 0x7d 138.6 to 141.4 0x1e 0x36 0x4e 0x66 0x7e 167.3 to 170.7 0x1f 0x37 0x4f 0x67 0x7f 202.9 to 207.1 0x20 0x38 0x50 0x68 0x7f 234.6 to open 0x21 0x39 0x51 0x69 0x7f r addr1 (k?) iout_cal_gain (m?) 0 to 8.4 0.4 9.4 to 18 0.8 21.2 to 44.7 1.2 50.5 to 116.2 1.6 138.6 to open 2.0 max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 14 downloaded from: http:///
internal bias regulators the max15301 analog circuitry is powered by an internal 3.3v regulator (3p3). the max15301 also has an inter - nal bias regulator to generate a 1.8v rail (1p8) to power internal digital circuitry. bypass the 3p3 pin to sgnd with a 4.7f ceramic (x5r or better) capacitor. bypass 1p8 to dgnd with a 10f ceramic (x5r or better) capaci - tor. these internal regulators are not designed to power external circuitry. input voltage feed-forward the max15301 uses input voltage feed-forward tech - niques to provide excellent line regulation. connect the insns pin to the powertrain input voltage through a 2k? series resistor for input voltage feed-forward and telem - etry. the voltage at insns is sampled every 4s. the max15301 does not enable dc-dc conversion if the voltage at insns is below the pmbus vin_uv_fault_ limit threshold (default 4v) or below the vin_on, vin_off limits (default 6v rising and 5.5v falling, respec - tively.) the user can read back the measured input volt - age value using the pmbus read_vin command. output on/off control the max15301 features both a hardware enable input (en pin) and a pmbus enable function. the factory default for the enable functions is that the max15301 can be enabled by either an assertion of the hardware en pin to a logic-high level or by issuing a pmbus enable com - mand. the enable functionality can be changed using the pmbus on_off_config pmbus command (see the pmbus specification for details). the max15301 default configuration allows the output to be enabled either by driving the en input to a logic-high level, or by sending the pmbus operation command. the enable criteria can be changed using the pmbus on_off_config command. device initialization the max15301 includes power-on reset circuits that monitor the internal bias supplies and the external supply voltage. when all supplies are above their uvlo thresh - olds, the following self-test sequence occurs: 1) run self test and crc check on the memory. 2) read resistor settings and set command values and program working memory accordingly. 3) confirm absence of any faults that would prevent turn- on. 4) begin wait for a valid output enable condition (hard - ware or pmbus command). the power-up and initialization process takes approxi - mately 25ms, depending upon the specific combination of pin-strap resistor values to be read. the max15301 will not enable output regulation until initialization is complete. figure 2. startup timing diagrams enabled during initialization 10ms v out pg en v in enabled after initialization 2ms v out pg en v in t2 t1 t4 t3 max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 15 downloaded from: http:///
output voltage sequencing in a system with multiple max15301 devices or other pmbus controlled ics, output voltage sequencing can be achieved by configuring each power supply with different turn-on/turn-off delays and output rise/fall times. all power supplies are then commanded to turn on (or off) simultane - ously using a combined en signal, or by using the pmbus group command protocol. the max15301 supports soft-start and soft-stop func - tionality as shown in figure 3 . the pmbus ton_rise and toff_fall commands determine the soft-start and soft-stop ramp times. the ton_delay command sets the time from a valid enable condition to the beginning of the output voltage ramp. similarly, the toff_delay command sets the time between loss of valid enable con - dition and the beginning of the output ramp down to 0v. the default setting for ton_delay is the minimum value of 1ms and the default setting for the ton_rise is 5ms. the output voltage slew-rates for turn-on and turn-off are given by vout_command ton_rise and vout_command toff_fall, respectively. it is rec - ommended to set ton_rise and toff_fall to at least 1ms to prevent excessive inrush currents due to high dv/dt. the output voltage ramp-up rises monotonically above 300mv regardless of input voltage, output voltage, or prebias voltage on the output. note that the max15301 initiates the intune calibration process after the soft-start ramp-up is complete. startup with prebias the max15301 supports soft-start into a prebias output voltage condition. a prebias condition occurs when there is already a voltage at the output of the power supply before it has been enabled. this can be caused by pre - charged output capacitors, or a parasitic esd diode in the load ic that pulls the output up to another system supply rail. when en is asserted, the max15301 checks the output for the presence of prebias voltage. if the prebias voltage is less than 200mv, startup is performed nor - mally assuming no prebias. if the prebias is greater than 200mv but below the target set point for the output, the max15301 ramps up the output voltage from the prebias voltage to the regulation set point as shown in figure 4 . if the prebias is above the vout_ov_fault_limit value, the max15301 does not attempt soft-start. if prebias was detected at the time of enable, the max15301 saves the prebias voltage level in a register and terminates the output voltage ramp-down at the pre - bias voltage when disabled. voltage tracking the max15301 supports voltage tracking of the output from a reference input. to select the tracking mode, connect the set pin to sgnd. the max15301s output tracks the v track voltage with a preset ratio governed by an internal feedback divider (rdiv) and an external resistive voltage-divider (r1, r2) which is placed from the supply being tracked to sgnd ( figure 5 ). the center tap of the external divider should be connected to the cio input. in tracking mode, v out is regulated to the lower of: track out v r1 vx rdiv r1 r2 = + or the output set-point voltage v out(set) as determined by the vout_command. as seen in the above equa - tion, if the resistor-divider ratio rr = r1/(r1 + r2) is chosen such that it is equal to the operational rdiv, the output voltage follows the tracking voltage coincidentally ( figure 6 a ). for all other cases, the v out follows a ratio - metric tracking ( figure 6 b ) depending on the ratio of rr and rdiv. the max15301 automatically selects rdiv based on the output set-point voltage as shown in table 5 . for example, if v out(set) is set to 1.6v by the vout_ figure 3. turn-on/-off delays and soft-start/-stop times figure 4. startup into a prebiased output voltage time v out v en ton_delay toff_delay toff_ fall ton_rise voltage switching node time v out t on_delay max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 16 downloaded from: http:///
command, rdiv is set to 0.54247. for a reliable voltage tracking, it is recommended that once the ic is powered up, the vout_command should not be changed so as to cause a change to the operational rdiv ( table 5 ). if such a change in vout_command is required, the user should save the new vout(set) in the device memory (using store_user_all_command) and recycle the input power to set a new rdiv operational value. for simplicity, fix r1 at 10k? and use the following equation to determine r2: track div out v r2 10k 1 rv ?? = ? ?? ?? for the best voltage regulation, rr should be set such that the final v out tracking target volt - age is slightly higher than the output set-point volt - age determined by vout_command. the out - put ramp tracks the v track input as shown in figure 6 until reaching the vout_command value. if the application requires continuous ratiometric tracking, vout_command should be set higher than the desired v out tracking target or left at the 5.0v default value. in this case, there is a small regulation inaccuracy due to the tolerance of the external resistors. table 5. required divider ratio (rdiv) as a function of v out figure 5. tracking mode configuration figure 6. tracking vout_command (v) rdiv < 0.65 0.99547 0.65 to < 1.12 0.88222 1.12 to < 1.28 0.76897 1.28 to < 1.50 0.65572 1.50 to < 1.82 0.54247 1.82 to < 2.29 0.42922 2.29 to < 3.12 0.31597 3.12 to < 5.25 0.20272 cio set max15301 v track v out r1 r2 step-down converter rdiv = rr coincident tracking (track to target) rdiv rr ratiometric mode (a) (b) voltage time v out v track v out v track voltage time v out(set) x v track 10k ? 10k ? + r2 max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 17 downloaded from: http:///
output voltage margining the max15301 supports voltage margining, which can be used to test the end equipments design margin associat - ed with power-supply variation. the margin setpoint com - mands vout_margin_high and vout_margin_ low are set to 5% of vout_command by default, but can be changed via the pmbus interface. output voltage margining is controlled by the operation command. output voltage ranges and fault limits the max15301 features output undervoltage and over - voltage protection. the pmbus vout_ov_fault_limit is set to 115% of vout_command by default, and vout_uv_fault_limit is set to 85%. these thresh - olds can be changed through pmbus and set anywhere between 0v and the lower of either the adc full-scale value or vout_max (vout_max is 110% of vout_ command by default. the max15301 continuously monitors the output voltage. if the voltage exceeds the protection limits, the max15301 follows the actions prescribed by the vout_ov_fault_ response or vout_uv_fault_response com - mands as appropriate. by default, an overvoltage fault results in an immediate shutdown with no retry attempts, whereas undervoltage faults are ignored. the fault response commands can be changed at any time, but changes to the fault-response commands only take effect when the output is disa bled. output-overcurrent protection the max15301 monitors the voltage across the output inductor resistance (or other resistive sense element) to provide output current monitoring and overload protection. the voltage signal at the current-sense element is divided by the iout_cal_gain value to yield output current in amps. the value of iout_cal_gain is initially set by the addr1 resistance according to table 4b and should be set as close as possible to the inductor dcr (or the resis - tive sense elements resistance.) more accurate output current measurement can be achieved by calibrating the iout_cal_gain value; contact maxim for an application note describing the read_iout calibration process. the overcurrent fault threshold is set by the iout_oc_ fault_limit command; the default value is 25a. if an overcurrent condition is detected, the max15301 shuts down, delays for 700ms, and then attempts to restart the regulator. this process repeats indefinitely until the fault condition no longer persists. this fault response behavior can be changed using the pmbus iout_oc_fault_ response command . fault handlingthe max1 5301 monitors input voltage, output voltage, out - put current, and both internal and external temperatures. the fault thresholds and responses are factory-set, but may be changed using pmbus commands. fault detection can be individually enabled or disabled for the parameters through pmbus. the default limits are as indicated in table 6 . the response to a fault condition can be changed through pmbus. nonvolatile pmbus memory the max15301 includes three nonvolatile stores for pmbus configuration values. the first is the maxim store, which contains a read-only copy of all default command settings. the next is the read/write-accessible default store, which is intended to contain an equipment manu - facturers preferred or suggested settings. third is the read/write accessible user store, which is intended to store the end-users preferred settings. when the device is enabled, a combination of the pin-con - figurable command values and the contents of the user store are loaded into working memory. any command values that have been edited and stored to the user memory takes precedence over their corresponding pin- configured values. equipment manufacturers should ensure that the default and user stores are saved with duplicate copies of the manufacturers preferred or suggested com - mand values. in this manner, an end user can restore the default memory and save to the user store any time they wish to return the device to the manufacturers original configuration. special security commands and features are included so that a manufacturer user can store and lock the regula - tors configuration on a command-by-command basis. contact maxim for application notes describing these security features. table 6. fault conditions fault condition default threshold range v in overvoltage 14v 0 to 14.7v v in undervoltage 4.2v 0 to 14.7v v out overvoltage vout_command x 115% 0 to 5.5v v out undervoltage vout_command x 85% 0 to 5.5v i out overcurrent 25a 0 to 30a overtemperature 115c -40c to +150c max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 18 downloaded from: http:///
temperature sensing the max15301 supports remote temperature sensing in addition to sensing its own internal temperature. the max15301 uses a v be measurement internally and at the tempx input to compute temperature. this tech - nique is widely employed because it requires no calibra - tion of the sensor. any pn junction can be used as a temperature sensor. the 2n3904, 2n2222 transistors and integrated thermal diodes found in microprocessors, fpgas, and asics are commonly used temperature sensors. connect a 100pf filter capacitor as shown in figure 7 to ensure accurate temperature measurements. the device temperature and thermal fault thresholds are programmed through the pmbus interface. the default value for the thermal shutdown threshold is +115c. the max15301 shuts down and pg pulls low when it crosses the temperature fault threshold. power good (pg) pg, power good, is an open-drain output used to indi - cate when the max15301 is ready to provide regulated output voltage to the load. during startup and during a fault condition, pg is held low. pg is asserted high after the output has ramped to a voltage above the power_good_on (5eh) threshold and a successful intune calibration has completed. if the output regula - tion voltage falls below the power_good_off (5fh) threshold, pg will be deasserted. pmbus digital interface the max15301 is a pmbus-compatible device that includes many of the standard pmbus commands. a pmbus 1.2-compliant device uses the system management bus (smbus) version 2.0 for transport pro - tocol and responds to the smbus slave address. in this data sheet, the term smbus is used to refer to the electri - cal characteristics of the pmbus communication using the smbus physical layer. the term pmbus is used to refer to the pmbus command protocol. the max15301 employs six standard smbus protocols (write byte, read byte, write word, read word, write block, and read block) to program output voltage and warning/faults thresholds, read monitored data, and pro - vide access to all manufacturer-specific commands. the max15301 also supports the group command. the group command is used to send commands to more than one pmbus device. it is not required that all the devices receive the same command. however, no more than one command can be sent to any one device in one group command packet. the group command must not be used with commands that require the receiving device to respond with data, such as the status_byte command. when the max15301 receives a command through this protocol, it begins execution immediately of the received command after detecting the stop condition. when the data word is transmitted, the lower order byte is sent first and the higher order byte is sent last. within any byte, the most significant bit (msb) is sent first and the least significant bit (lsb) is sent last. contact the factory for detailed pmbus command support. supported pmbus commands the max15301 supports the standard pmbus commands given in table 7 . contact maxim for an application note that describes all max15301 pmbus command function - ality in detail. a single pair of pullup resistors (one each for scl and sda) is required for each shared bus as shown in figure 8 . consult the smbus 2.0 specifications as well as the guaranteed drive capability of sda in the electrical characteristics table to determine the value of the pullup resistors. figure 7. temperature sensing with a 2n3904 npn transistor figure 8. smbus multidevice configuration tempx 100pf sgnd max15301 scl r pullup r pullup v logic sda sclsda max15301 max15301 max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 19 downloaded from: http:///
table 7. pmbus command summary command code command name smbus transfer type # of data bytes min max default value units 0x01 operation r/w byte 1 0x40 0x02 on_off_config r/w byte 1 0x16 0x03 clear_faults send byte 0 0x10 write_protect r/w byte 1 0 0x11 store_default_all send byte 0 0x12 restore_default_all write byte 0 0x15 store_user_all send byte 0 0x16 restore_user_all write byte 0 0x19 capability read byte 1 0xa0 0x20 vout_mode read byte 1 0x14 0x21 vout_command r/w word 2 0.5 5.25 set pin resistor setting v 0x22 vout_trim r/w word 2 0 v 0x23 vout_cal_offset r/w word 2 0 v 0x24 vout_max r/w word 2 vout_command + 10% v 0x25 vout_margin_high r/w word 2 vout_command + 5% v 0x26 vout_margin_low r/w word 2 vout_command - 5% v 0x27 vout_transition_rate r/w word 2 0.1 mv/s 0x28 vout_droop r/w word 2 0 m? 0x33 frequency_switch r/w word 2 300 1000 sync pin resistor setting khz 0x35 vin_on r/w word 2 4 12 6 v 0x36 vin_off r/w word 2 4 12 5.5 v 0x37 interleave r/w word 2 see table 2 0x38 iout_cal_gain r/w word 2 addr1 pin resistor setting m? 0x39 iout_cal_offset r/w word 2 0 a 0x40 vout_ov_fault_limit r/w word 2 vout_command + 15% v 0x41 vout_ov_fault_response r/w byte 1 0x80 0x44 vout_uv_fault_limit r/w word 2 vout_command - 15% v 0x45 vout_uv_fault_response r/w byte 1 0x00 0x46 iout_oc_fault_limit r/w word 2 25 a 0x47 iout_oc_fault_response r/w byte 1 0xbf 0x4f ot_fault_limit r/w word 2 115 c 0x50 ot_fault_response r/w byte 1 0xc0 0x51 ot_warn_limit r/w word 2 95 c max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 20 downloaded from: http:///
table 7. pmbus command summary (continued) command code command name smbus transfer type # of data bytes min max default value units 0x55 vin_ov_fault_limit r/w word 2 14 v 0x56 vin_ov_fault_response r/w byte 1 0xc0 0x59 vin_uv_fault_limit r/w word 2 4.2 v 0x5a vin_uv_fault_response r/w byte 1 0xc0 0x5e power_good_on r/w word 2 vout_command - 10% v 0x5f power_good_off r/w word 2 vout_command - 15% v 0x60 ton_delay r/w word 2 5 ms 0x61 ton_rise r/w word 2 5 ms 0x64 toff_delay r/w word 2 1 ms 0x65 toff_fall r/w word 2 5 ms 0x78 status_byte read byte 1 0x79 status_word read word 2 0x7a status_vout read byte 1 0x7b status_iout read byte 1 0x7c status_input read byte 1 0x7d status_temperature read byte 1 0x7e status_cml read byte 1 0x88 read_vin read word 2 v 0x8b read_vout read word 2 v 0x8c read_iout read word 2 a 0x8d read_temperature_1 read word 2 c 0x8e read_temperature_2 read word 2 c 0x94 read_duty_cycle read word 2 % 0x95 read_frequency read word 2 khz 0x98 pmbus_revision read byte 1 0x99 mfr_id r/w block 8 null 0x9a mfr_model r/w block 13 null 0x9b mfr_revision r/w block 7 null 0x9c mfr_location r/w block 8 null 0x9d mfr_date r/w block 6 null 0x9e mfr_serial r/w block 13 null 0xad ic_device_id read block 8 max15301 0xae ic_device_rev read word 8 max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 21 downloaded from: http:///
design procedure switching frequency selection the first step in selecting a buck controllers output filter is to select the desired switching frequency (f sw ) for the pwm. the max15301 will switch at frequencies in the range of 300khz f sw 1mhz. select a low frequency for higher efficiency. use a higher frequency to reduce the size of the external filter components and to improve transient response. also consider system frequency requirements when choosing f sw , such that the harmonics of the switch - ing frequencies do not interfere with the system operation. the switching frequency for the max15301 is set by the sync pin connection per table 3 . the switching frequency can be changed via the frequency_switch pmbus command at anytime the controller is disabled. the selec - tion of 600khz provides a good balance of efficiency, small size, and good transient response. inductor selection three key inductor parameters must be specified to select an inductor for operation with the max15301: inductance value (l), inductor saturation current (i sat ), and maxi - mum dc resistance (dcr). 1) inductor value selection: for automatic compensa - tion using intune technology, the inductor is selected such that the peak-to-peak inductor ripple current (lir) is 20% to 40% of the maximum operating cur - rent (i outmax ). using a low lir ratio (higher inductor value) will result in higher dc resistance in the inductor and will reduce efficiency. using a high value of lir will increase the rms current which will also decrease efficiency. maxim recommends 30% for a peak-to- peak ripple to maximum operating current ratio (lir = 0.3). the nominal inductor value can now be calculated using lir, f sw , v in , v out , and i outmax (the maxi - mum dc load current) using the following equation: out in out in sw out v (v v ) l v f i lir 0.2 lir 0.4 ? = ? command code command name smbus transfer type # of data bytes min max default value units 0xd0 adaptive_mode write byte 2 0x024b 0xd3 feedback_effort r/w word 2 0.5 0xd5 loop_config r/w word 2 0x0100 0xdb comp_model r/w block 6 0.03167, 0.5, 0.5 0xe0 manuf_conf r/w block 32 0 0xe1 manuf_lock r/w byte 2 0 0xe2 manuf_passwd r/w word 2 0xe3 user_conf r/w block 32 0 0xe4 user_lock r/w byte 2 0 0xe5 user_passwd r/w word 2 0 0xe6 security_level read byte 1 0 0xe7 deadtime_gctrl r/w block 19 0xe8 zetap r/w word 2 1.5 0xea restore_maxim_all r/w byte 0 0xf8 ext_temp_cal r/w block 4 1.004363, 0 max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 22 downloaded from: http:///
the exact inductor value in this range is not critical and can be adjusted to make trade-offs among size, cost, and efficiency. a higher inductance can increase efficiency by reducing the rms current. lower inductor values minimize size and cost. lower inductor values may also improve transient response but reduce effi - ciency due to higher peak currents. 2) the selected inductors saturation current rating (i sat ) must exceed the user-defined current limit. i sat should generally be selected such that it is greater than i lim + lir/2 +10% to provide adequate margin in the event of a large load transient. it is important to select an inductor that has a high enough i sat to satisfy this requirement though this parameter typically forces a certain dimension of inductor to be used. 3) finally, the user should select an inductor with minimal dcr (dc series resistance) to reduce overall losses in efficiency. output capacitor selection the max15301 has been optimized to operate with low-esr output capacitors. high-esr capacitors can be added, but would provide little benefit to system perfor - mance. the output capacitor requirement is dependent upon two considerations: 1) low output ripple voltage 2) load current transient envelope low ripple voltage is easily achieved with an all-ceramic output capacitor. when all-ceramic output capacitors are used, load current transient envelope is the primary concern for capacitor selection. designs with little load transients can use fewer capacitors and designs with more dynamic load content will require more load capaci - tors to reduce output sag and soar. to achieve low ripple voltage, the output capacitor bank must have a small esr value. to calculate the maximum allowable esr, start with the maximum desired output ripple voltage (typically 0.5% to 1% of v out ) and calculate the maximum esr using the lir value from above. ripple outmax v esr i lir = an esr on the order of 1m is typically required. the use of two or more 100f ceramic capacitors in parallel is typically sufficient to achieve a good ripple voltage. to meet load current transient envelope requirements, the max15301 compensates for output filters with natural (resonant) frequencies f lc such that the following is met: sw lc f 25 70 f ? where: ( ) lc f 1 2 lc = ? therefore: sw sw 22 1 25 1 70 c l 2f l 2f ?? ?? ? ?? ?? ?? ?? most 600khz pol designs (10a to 25a) are satisfied using between 200f to 1000f of ceramic output capacitance and no additional electrolytic capacitors. the intune adap - tive compensation permits a very large range of output decoupling capacitances. output capacitances resulting in f sw /f lc ratios greater than 60 are acceptable. this capa - bility is important in module applications where the output capacitance may be unknown or not well controlled. in general, smaller output voltage deviation is achieved by using greater capacitance. input capacitor selection the input filter capacitor reduces peak current drawn from the power source and reduces noise and voltage ripple on the input caused by the switching circuitry. the value of the input capacitor is selected to limit the ripple voltage (v) as follows: out out out in in in sw vv i1 vv c fv ?? ? ?? ?? d where dv is the input ripple voltage. this calculation assumes there is measurable inductance back to the original v in source thus this calculation provides low source impedance at the input of the dc-dc converter. the capacitance requirement is greatest when the duty cycle is 50% and decreases as duty cycle increases (i.e. input voltage increases). the input capacitor must meet the ripple current require - ment (i rms ) imposed by the switching currents as defined by the following equation: out in out rms load(max) in v (v v ) ii v ? = i rms attains a maximum value when the input volt - age equals twice the output voltage (v in = 2v out ), max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 23 downloaded from: http:///
so i rms(max) = i load(max) /2. for most applications, nontantalum capacitors (ceramic, aluminum, polymer, or os-con) are preferred at the inputs due to the robustness of non-tantalum capacitors to accommodate high inrush currents of systems being powered from very low imped - ance sources. additionally, two (or more) smaller-value low-esr capacitors should be connected in parallel to reduce high-frequency noise. mosfet selection the following guidelines address the challenge of selecting the appropriate mosfets for high-current appli - cation. the high-side mosfet (q h ) must be able to dissipate the resistive losses plus the switching losses at both v in(min) and v in(max) . calculate both these sums. ideally, the losses at v in(min) should be roughly equal to losses at v in(max), with lower losses in between. if the losses at v in(min) are significantly higher than the losses at v in(max) , consider increasing the size of q h (reducing r ds(on) but increasing c gate ). conversely, if the losses at v in(max) are significantly higher than the losses at v in(min) , consider reducing the size of q h (increasing r ds(on) but reducing c gate ). if input voltage does not vary over a wide range, the minimum power dissipation occurs where the resistive losses equal the switching losses. choose a low- side mosfet that has the lowest possible on-resistance (r ds(on) ), comes in a moderate-sized package, and is reasonably priced. ensure that the dl gate driver can sup - ply sufficient current to support the gate charge and the current injected into the parasitic gate-to-drain capacitor caused by the high-side mosfet turning on; otherwise, cross-conduction problems can occur. mosfet power dissipation worst-case conduction losses occur at the duty cycle extremes. for the high-side mosfet (q h ), the worst-case conduction losses occur at the minimum input voltage: h 2 out q cond out ds(on) in(min) v p ir v ? = generally, a small high-side mosfet is desired to reduce switching losses at high input voltages. however, the r ds(on) required to stay within package-power dissipa - tion often limits how small the mosfets can be. again, the optimum occurs when the switching losses equal the conduction (r ds(on) ) losses. calculating the power dissipation in high-side mosfets (nh) due to switching losses is difficult since it must allow for difficult quantifying factors that influence the turn-on and turn-off times. these factors include the internal gate resistance, gate charge, threshold voltage, source induc - tance, and pcb layout characteristics. the following switching-loss calculation provides only a very rough estimate and is no substitute for prototype evaluation, preferably including verification using a ther - mocouple mounted on q h : h in(max) load sw g q sw swh-source in(max) load sw g(sw) swh-sink 2 oss in(max) sw v i fq 1 p 2i v i fq 1 2i cv f 2 ? ?? = ???? ?? ?? + ???? ?? ?? ?? + ?? ?? where c oss is the q h mosfets output capacitance, q g(sw) is the charge needed to turn on the high-side mosfet, i dh-source is the peak gate-drive source current (2a typ), and i dh-sink is the peak gate-drive sink current (4a typ). switching losses in the high-side mosfet can become an insidious heat problem when the maximum input voltage is applied due to the squared term in the switching-loss equa - tion above. if the high-side mosfet chosen for adequate r ds(on) at low input voltages becomes extraordinarily hot when biased from v in(max) , consider choosing another mosfet with lower parasitic capacitance. for the low-side mosfet (q l ), the worst-case power dis - sipation always occurs at the maximum input voltage and is due primarily to conduction losses. switching losses in the low-side fet are minimal because it is turned on and off when the body diode is conducting and hence under zero-voltage conditions. l 2 out q cond out ds(on) in(max) v p 1 ir v ? ???? = ? ???? the worst case for mosfet power dissipation occurs under heavy load conditions that are greater than i out(max) , but are not quite high enough to exceed the current limit and cause the fault latch to trip. the mosfets must have a good-sized heatsink to handle the overload power dissipation. the heatsink can be a large copper field on the pcb or an externally mounted device. avoiding dv/dt turn-on of the low-side mosfet at high input voltages, fast turn-on of the high-side mosfet can momentarily turn on the low-side mosfet due to the high dv/dt appearing at the drain of the low-side mosfet. the high dv/dt causes a current flow through max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 24 downloaded from: http:///
the miller capacitance (c rss ) and the input capacitance (c iss ) of the low-side mosfet. improper selection of the low-side mosfet that results in a high ratio of c rss / c iss makes the problem more severe. to avoid this prob - lem, minimize the ratio of c rss /c iss when selecting the low-side mosfet. adding a 1 to 4.7 resistor in series with the high-side mosfet gate can slow the high-side mosfet turn-on. similarly, adding a small capacitor from the gate to the source of the high-side mosfet has the same effect. however, both methods work at the expense of increased switching losses (lower efficiency). boost capacitor the max15301 uses a bootstrap circuit to generate the necessary gate-to-source voltage to turn on the high-side mosfet. the selected n-channel high-side mosfet determines the appropriate boost capacitance value (c bst in the typical operating circuit ) according to the following equation: g bst bst q c v = ? where q g is the total gate charge of the high-side mosfet and dv bst is the voltage variation allowed on the high-side mosfet driver after turn-on. choose dv bst such that the available gate-drive voltage is not significantly degraded (e.g. dv bst = 100mv to 300mv) when determining c bst . for most applications, a 0.22f low-esr ceramic capaci - tor will suffice. current sense the max15301 uses lossless dcr current sensing to reduce the overall power dissipation and improve efficiency. lossless sensing is configured by connect - ing a series rc circuit across the inductor as shown in figure 9 . select the resistor and capacitor such that their time constant is equal to that of the inductor and its dcr: ll l rc dcr = use the typical inductance and dcr values provided by the inductor manufacturer. use high accuracy and low tempco c0g ceramic capacitors for c l . the maximum sense voltage produced using lossless sensing is: dcrp dcrn out(max) v v dcr i ?= carefully observe the pcb layout guidelines provided in the datasheet to ensure the noise and dc errors do not corrupt the differential current-sense signals seen by dcrp and dcrn. place the rc network close to the inductor and kelvin sense the voltage across the capacitor. current limit the max15301 provides current-fault protection utilizing inductor dcr current sense. a resistor connected to the addr1 input can be used to set the current-sense cali - bration resistance in the max15301 as shown in table 4b. for coarse adjustment of the overcurrent protection using external pin resistances only, select the raddr1 value that best satisfies the following relationship: out(max) iout_cal_gain dcr i 25a ? optionally, for best precision, set iout_cal_gain to match the actual inductor dcr and adjust the overcurrent fault threshold iout_oc_fault_limit directly using pmbus commands. output voltage remote sensing the max15301 uses two dedicated inputs (outp and outn) for the output differential voltage sensing to reduce the common-mode noise sensitivity. this sensing circuitry is part of the feedback loop. the output voltage is connected to the max15301 directly through these two inputs without the need for an external resistive divider. the pcb traces to the outp and outn pins should be routed as a differential pair to the desired regulation sense point to minimize noise induced in the sensed signal. babybuck component selection the max15301 features an internal dc-dc switching regulator to power internal circuitry and provide the gate- drive voltage for the external mosfets. competing parts figure 9. lossless dcr current sensing max15301 dh dl dcrp dcrn n l r l c l c out n max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 25 downloaded from: http:///
with internal driver circuits use linear regulators to provide these voltages which leads to significant efficiency loss when operating from an input voltage above ~6v. the patent-pending babybuck circuit improves overall effi - ciency in a typical application by more than 1% at full load and more than 10% in lightly loaded conditions. the babybuck uses a tiny (1008-size) low current inductor connected across lbi and lbo ( figure 10 ). a 10h inductor with a saturation rating of at least 200ma and a 2.2f ceramic capacitor at gdrv pin is recom - mended. in addition to the efficiency improvement from using a dc-dc regulator to power the mosfets, the babybuck can vary the gate-drive voltage to improve the efficiency over different load current conditions. the variable gate- drive function can be disabled and the gate-drive voltage levels can be modified using pmbus commands. for applications where efficiency is not critical, the induc - tor can be omitted and the babybuck automatically oper - ates as a linear regulator ( figure 11 ). in this configuration, bypass gdrv to pgnd with a 2.2f ceramic capacitor and connect lbi to pwr through a 100k resistor. the linear regulator can be bypassed altogether with an exter - nal power source. an external 5v to 9v supply can also be applied directly to the gdrv pin to power the gate drivers ( figure 12 ). pull lbi up to pwr with a 2k resis - tor and leave lbo unconnected to allow external gate drive supply. design examples see table 8 for the component values in the typical operating circuit . for additional examples and detailed layout information, refer to the max15301 evaluation kit. figure 10. gate drivers powered by switching regulator figure 11. gate drivers powered by linear regulator figure 12. gate drivers powered externally gdrv v in 2.2f 10h pwr 5v to 8.5v gdrv command lbo lbi dh lx dl bst dpwm babybuck fb max15301 gdrv 2.2f pwr v in 5v to 8.5v gdrv command lbo lbi dh lx dl bst dpwm ldo fb max15301 100k ? gdrv v ex t 5v to 9v pwr lbo lbi dh lx dl bst dpwm 2k ? 2.2f max15301 v in max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 26 downloaded from: http:///
applications information pcb layout guidelinescareful pcb layout is critical to achieve clean and stable operation. the switching power stage requires particular attention. follow these guidelines for best thermal perfor - mance and signal integrity: 1) when using a resistor to set a command value, con - nect its return terminal to sgnd. 2) connect the power ground plane (connected to pgnd), digital return (connected to dgnd), and ana - log ground plane (sgnd) at one point near the device. 3) bypass gdrv to pgnd, 3p3 to sgnd, and 1p8 to dgnd with ceramic decoupling capacitors. place the capacitors as close as possible to the pins. 4) minimize the length of the high-current loop from the input capacitor, the high-side switching mosfet, and the low-side mosfet back to the input-capacitor negative terminal. 5) provide enough copper area at and around the switch - ing mosfets and inductors to aid in thermal dissipa - tion. maintain a good balance between the lx copper area for thermal performance and electromagnetic radiation. 6) route high-speed switching nodes (bst, lx, dh, and dl) away from sensitive sense inputs (outp, outn, dcrp, and dcrn). 7) route the dcrp, dcrn and outp, outn traces as differential pairs. 8) connect pgnd of the max15301 as close as possible to the source of the low-side mosfet. table 8. typical component values component application 1 application 2 application 3 input supply 12v 9v 12v output voltage 1.2v 0.9v 1.0v r set 26.1k ? 11.0k ? 14.7k ? output current 25a 8a 35a r addr1 0 ? to 8.4k ? 21.2k ? to 44.7k ? 0 ? to 8.4k ? r addr0 user deined (see table 4a) user deined (see table 4a) user deined (see table 4a) switching frequency 600khz 450khz 850khz r sync 12.7k ? 8.25k ? 31.6k ? inductor l1 wrth 744308033, 330nh, 370 ? coilcraft xal7030-601me_, 600nh, 3m ? coilcraft slc1049-125 inductor l2 tdk nlcv25t-100k-pf, 10h tdk nlcv25t-100k-pf, 10h tdk nlcv25t-100k-pf, 10h r filter 665 ? 9.09k ? 2.10k ? c filter 1f 0.22f 0.22f high-side mosfet inineon bsc032ne2ls, 3.2m ? (5mm x 6mm) inineon bsz060ne2ls, 6.5m ? (3.3mm x 3.3mm) inineon bsc032ne2ls, 3.2m ? (5mm x 6mm) low-side mosfet inineon bsc010ne2ls, 1.0m ? (5mm x 6mm) inineon bsz018ne2ls, 1.8m ? (3.3mm x 3.3mm) inineon bsc010ne2ls, 1.0m ? (5mm x 6mm) output capacitance 6 x 100f, x5r, 1206, 6.3v 2 x 100f, x5r, 1206, 6.3v 10 x 100f, x5r, 1206, 6.3v input capacitance 3 x 47f, x5r, 1210, 16v 1 x 47f, x5r, 1210, 16v 4 x 47f, x5r, 1210, 16v max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 27 downloaded from: http:///
thermal layout the max15301 is available in a small 5mm x 5mm tqfn package with exposed pad to remove heat from the inter - nal semiconductor junctions. the exposed pad must be soldered to the copper on the pcb directly underneath the device package reducing the ja down to approxi - matly 40c/w. the max15301 will shut down if its tem - perature increases beyond +115c. (this threshold can be changed using a pmbus command). an evaluation kit is available that demonstrates the recommended layout practices for the max15301. max15301 l2 10 f h 4.7 f f 0.22 f f load cl r l l1 10 f f 2.2 f f r cio v out c out r set r addr1 r addr0 7 2n3904 enable ext clk 3.3v logic smbus interface 21 18 22 14 13 24 3 8 2k ? 2k ? 10k ? 3k ? 3k ? 10k ? lx nhnl gdrv pwr lxsns insns bst dh v in dcrp dcrn outp outn power groundsignal ground dl pgnd lbilbo tempx addr0 addr1 set cio en sync pg scl sda salrt dgnd 3p31p8 c in , bulk 12 1 3210 11 95 23 24, 25 6 30 1731 27 26 1516 19 20 ep 100pf 1 f f typical operating circuit max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 28 downloaded from: http:///
+denotes lead(pb)-free/rohs-compliant package. *ep = exposed paddle. part temp range pin-package firmware max15301aa01+ck -40c to +85c 32 tqfn-ep* 4018 package type package code outline no. land pattern no. 32 tqfn-ep t3255m+51 21-0140 90-0013 package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. chip information process: bicmos ordering information max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry www.maximintegrated.com maxim integrated 29 downloaded from: http:///
revision number revision date description pages changed 0 4/12 initial release 1 11/12 updated data sheet to relect performance and operation of current silicon 1C35 2 3/13 removed the current sharing function to be compliant with latest irmware; in the electrical characteristics table: changed the power-good threshold parameter from 90%v out (typ) to 95%v out (typ), changed v gdrv from 4.2v(min) and 9.0v(max) to 5.2v(min) and 8.5v(max), and updated the pmbus/i 2 c parameters; updated figures 1, 8, and 9, tables 9 and 10, the external synchronization section, and the typical operating circuit 1C5, 7, 10, 11, 12, 14, 16C24, 31 3 11/13 rewrote and updated speciications to relect production irmware (version 4018) functionality and features all revision history maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and speciications without n otice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max15301 intune automatically compensated digital pol controller with driver and pmbus telemetry ? 2013 maxim integrated products, inc. 30 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///

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