max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package evaluation kit available 19-0990; rev 6; 1/15 general description the max8902a/max8902b low-noise linear regulators deliver up to 500ma of output current with only 16? rms of output noise in a 100khz bandwidth. these regulators maintain their output voltage over a wide input range, requiring only 100mv of input-to-output headroom at full load. these ldos maintain a low 80? typical supply cur- rent, independent of the load current and dropout volt- age. the regulator control circuitry includes a programmable soft-start circuit and short circuit, reverse current, and thermal-overload protection. other features include an enable input and a power-ok out- put (max8902b only). the max8902a output voltage can be set to 1.5v, 1.8v, 2.0v, 2.5v, 3.0v, 3.1v, 3.3v, 4.6v, or 4.7v using the sela and selb inputs. the max8902b output voltage can be set between 0.6v and 5.3v with an external resistor voltage-divider. applications notebook computers mp3 and portable media players wireless headphones gps portable navigation devices smartphones features 1.7v to 5.5v input voltage range 0.6v to 5.3v output voltage range 16v rms output noise, 10hz to 100khz 80a operating supply current 92db psrr at 5khz guaranteed 500ma output current 1.5% output accuracy over load, line, and temperature 100mv (max) dropout at 500ma load < 1a shutdown supply current 700ma short-circuit protection thermal-overload protection output-to-input reverse current protection 2mm x 2mm x 0.8mm tdfn package ordering information in en out byp on off output 4.6v selb sela outs gnd ep 10 f input 4.7v to 5.5v 0.01 f 10 f max8902a typical operating circuits part features top mark max8902a ata+ pin-selectable output voltage abg max8902aata/v+ pin-selectable output voltage brp max8902b ata+ adjustable output voltage abh max8902bata/v+ adjustable output voltage adl + denotes a lead(pb)-free/rohs-compliant package. /v denotes an automotive qualified part. note: all devices are in an 8-pin, 2mm x 2mm tdfn package with an exposed paddle and operate over the -40? to +125? automotive temperature range. in en out byp on off output adjustable 0.6v to 5.3v gs pok fb gnd ep 10 f input 1.7v to 5.5v 0.01 f 10 f max8902b r1 r2 logic supply r3 100k to c pin configurations appear at end of data sheet.
max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package maxim integrated | 2 www.maximintegrated.com absolute maximum ratings stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. byp, en, in, out, sela, selb, pok to gnd, gs to gnd, fb, outs to gnd .....................................................-0.3v to +6.0v output short-circuit duration.....................................continuous continuous power dissipation (t a = +70?) tdfn (derate 11.9mw/? above +70?)...................953.5mw operating temperature range .........................-40? to +125? junction temperature range ............................-40? to +150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? soldering temperature (reflow) .......................................+260? electrical characteristics (v in = v en = 5v, outs = out, circuit of figure 2 (max8902a) and figure 3 (max8902b), t a = -40? to +125?, unless otherwise noted.) (note 1) parameter conditions min typ max units in input voltage range 1.7 5.5 v input undervoltage lockout v in rising, 100mv typical hysteresis 1.5 1.6 1.7 v out output voltage range v in v out + 0.1v 0.6 5.3 v output voltage accuracy v in = 1.7v to 5.5v for v out 1.4v, v in = (v out + 0.3v) to 5.5v for v out > 1.4v, i out = 0.1ma to 500ma -1.5 +1.5 % load regulation i out = 0.1ma to 500ma 0.02 % line regulation v in = 1.7v to 5.5v for v out 1.4v, v in = (v out + 0.3v) to 5.5v for v out > 1.4v, i out = 200ma 0.04 % v in 3.6v, t a +85c 50 100 v in 3.6v, t a +125c 120 dropout voltage (note 2) i out = 500ma v in = 1.7v 150 mv current limit v out = 95% of regulation, v in = v out + 0.5v 600 700 800 ma output noise i out = 100ma, f = 10hz to 100khz, c byp = 0.01f 16 v rms f = 5khz 92 f = 10khz 85 power-supply rejection ratio i out = 10ma f = 100khz 62 db outs ( max8902a only) outs input bias current in regulation 0.5 7.0 a fb ( max8902b only) fb threshold accuracy v in = 1.7v to 5.5v, i out = 0.1ma to 500ma 0.591 0.600 0.609 v t a = +25c -0.1 0.02 +0.1 fb input bias current v fb = 0.6v t a = -40c 0.03 a byp byp capacitor range regulator remains stable 1 100 nf byp startup current from byp to gnd during startup 50 a
max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package maxim integrated | 3 www.maximintegrated.com electrical characteristics (continued) (v in = v en = 5v, outs = out, circuit of figure 2 (max8902a) and figure 3 (max8902b), t a = -40? to +125?, unless otherwise noted.) (note 1) parameter conditions min typ max units gnd t a < +85c 80 120 gnd supply current i out = 0ma t a < +125c 160 a t a = +25c 0.001 +1 gnd shutdown current v in = 5.5v, en = 0v t a = +85c 0.01 a sela/selb ( max8902a only) when shorted to gnd or v in 500 select input resistance when open 1 m select input capacitance when open 10 pf en en rising 0.8 1.2 en falling, t a < +85c 0.4 0.7 enable input threshold v in = 1.7v to 5.5v en falling, t a < +125c 0.38 0.7 v t a = +25c -1 0.001 +1 enable input bias current v en = 0v to 5.5v t a = +85c 0.01 a pok (max8902b only) out rising 88 91 94 % pok threshold out voltage when pok switches out falling 88 % pok voltage, low i pok = 1ma 10 100 mv t a = +25c -1 0.001 +1 pok leakage current pok = 5.5v, v en = 0v t a = +85c 0.01 a thermal shutdown t j rising 165 thermal shutdown threshold t j falling 150 c output transient load transient i out = 50ma to 500ma to 50ma, t rise = t fall = 1s 25 mv/ p-p line transient v in = 4v to 5v to 4v, t rise = t fall = 5s, i out = 500ma 3 mv/ p-p in-to-out reverse voltage turnoff threshold in falling below out 10 mv note 1: all devices are production tested at t a = +25?. specifications over the operating temperature range are guaranteed by design and characterization. note 2: the dropout voltage is defined v in - v out , when v out is 5% lower than the value of v out when v in = v out + 0.5v.
typical operating characteristics (max8902a, v in = 3.6v, v out = 2.5v, t a = +25?, unless otherwise noted.) 0 40 20 80 60 120 100 140 023 145 quiescent current en = high, no load max8902a/02b toc01 input voltage (v) input current ( a) 2.500 2.502 2.501 2.504 2.503 2.505 2.506 0 200 100 300 400 500 load regulation max8902a/02b toc02 load current (ma) output voltage (v) 3.6v input 2.490 2.496 2.494 2.492 2.498 2.500 2.502 2.504 2.506 2.508 2.510 1.5 2.5 3.5 4.5 5.5 line regulation max8902a/02b toc03 input voltage (v) output voltage (v) 200ma load 40ms/div load transient response 50ma to 500ma to 50ma v out 100mv/div 200ma/div max8902a/02b toc04 i out t rise = t fall = 1 s 10 s/div line transient response v in 2v/div 2mv/div max8902a/02b toc05 v out 2.5v output 5 load 5v 4v 5v 100 s/div startup waveform v en 500mv/div 2v/div 200ma/div max8902a/02b toc06 i in v out 5 load c byp = 0.01 f 0 10 20 30 40 50 60 70 80 0 100 200 300 400 500 dropout voltage vs. load current max8902a/02b toc07 load current (ma) dropout voltage (mv) 3.6v input, 4.6v output preset the slope of the line indicates a 129m on-resistance in dropout psrr vs. frequency max8902a/02b toc08 10k 1k 100 10 100k frequency (hz) 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 psrr (db) max8902a ldo output-noise spectral density vs. frequency max8902a/02b toc09 frequency (hz) 100k 10k 1k 100 100e+0 1e+3 10e+3 10e+0 10 1m noise density (nv hz) max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package maxim integrated | 4 www.maximintegrated.com
detailed description the max8902a/max8902b low-noise, low-dropout lin- ear regulators deliver up to 500ma of output current with only 16? rms of output noise in a 100khz band- width. these regulators maintain their output voltage over a wide input range, requiring only 100mv of input- to-output headroom at full load. the max8902 maintains a low 80? typical supply cur- rent, independent of the load current and dropout volt- age. the regulator control circuitry includes a programmable soft-start circuit and short circuit, reverse current, and thermal-overload protection. other features include an enable input and a power-ok ( pok ) output (max8902b only). a simplified functional diagram is shown in figure 1. the max8902a output voltage can be set to 1.5v, 1.8v, 2.0v, 2.5v, 3.0v, 3.1v, 3.3v, 4.6v, or 4.7v using the sela and selb inputs. the max8902b output voltage can be set between 0.6v and 5.3v with an external resistor voltage-divider. enable (en) the max8902a/max8902b include an enable input, en. pull en low to shut down the output, or drive en high to enable the output. if shutdown is not needed, connect en to in. max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package maxim integrated | 5 www.maximintegrated.com pin description name pin max8902a max8902b function 1 in in regulator power input. connect in to a supply from 1.7v to 5.5v. bypass in with a 10f ceramic capacitor to gnd. 2 gnd gnd ground 3 en en enable input. a logic-low drives the output low through a 3k resistor and reduces the supply current to less than 1a. drive logic-high or connect to in for normal operation. sela output voltage select input. connect sela to gnd, in, or leave unconnected. the states of sela and selb are sampled when the regulator turns on and the output voltage is set as shown in table 2. 4 gs internally used. connect gs to gnd. selb output voltage select input. connect selb to gnd, in, or leave unconnected. the states of sela and selb are sampled when the regulator turns on and the output voltage is set as shown in table 2. 5 pok power-ok output. open-drain output that goes low when the output is above 91% of the nominal regulation voltage. pok is high impedance in shutdown or when the output is below the regulation voltage. outs output sense input. connect outs to the load at a point where accurate regulation is required, or connect outs directly to out. 6 fb feedback input. connect fb to the center of a resistor voltage-divider connected between out and gnd to set the output voltage. v fb regulates to 0.6v. 7 byp byp bypass input. connect a 0.01f ceramic capacitor from byp to out to achieve 16v rms output noise. adjust the value of this capacitor to control the output slew rate during startup. slew rate = (5v / ms) x (0.01f / c byp ) 8 out out regulator output. sources up to 500ma at the output regulation voltage. bypass with a 10f (< 0.03 esr) capacitor to gnd. ep ep exposed paddle. connect the exposed paddle to a ground plane to provide heat sinking.
max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package maxim integrated | 6 www.maximintegrated.com bypass (byp) the capacitor connected from byp to out filters the noise of the reference, feedback resistors, and regula- tor input stage and provides a high-speed feedback path for improved transient response. a 0.01? capaci- tor rolls off input noise at approximately 32hz. the slew rate of the output voltage during startup is also determined by the byp capacitor. a 0.01? capacitor sets the slew rate to 5v / ms. this startup rate results in a 50ma slew current drawn from the input at startup to charge the 10? output capacitance. voltage select sela selb 990k outs ea byp out gnd ref 0.6v byp max8902a only fb control en thermal protection pok in current limit reverse current protection max8902b only 0.54v max8902a max8902b figure 1. simplified functional diagram
max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package maxim integrated | 7 www.maximintegrated.com the byp capacitor value can be adjusted from 0.001? to 0.1? to change the startup slew rate according to the following formula: startup slew rate = (5v / ms) x (0.01? / c byp ) note that this slew rate applies only at startup, and that recovery from a short circuit occurs at a slew rate approximately 500 times slower. also note that, being a low-frequency filter node, byp is sensitive to leakage. byp leakage currents above 10na cause measurable inaccuracy at the output and should be avoided. protection features the max8902a/max8902b are fully protected from an output short circuit by a current-limiting and thermal- overload circuit. if the output is shorted to gnd, the output current is limited to 700ma (typ). under these conditions, the part quickly heats up. when the junction temperature reaches +165?, a thermal-limit circuit shuts off the output device. when the junction cools to +150?, the output turns back on in an attempt to reestablish regulation. while the fault persists, the out- put current cycles on and off, as the junction tempera- ture slews between +150? and +165?. the max8902a/max8902b are also protected against reverse current when the output voltage is higher than the input. in the event that extra output capacitance is used at the output, a power-down transient at the input would normally cause a large reverse current through a conventional regulator. the max8902a/max8902b include a reverse voltage detector that trips when in drops 10mv below out, shutting off the regulator and opening the pmos body diode connection, preventing any reverse current. thermal considerations the max8902a/max8902b are packaged in an 8-pin, 2mm x 2mm tdfn package with an exposed paddle. the exposed paddle is the main path for heat to leave the ic, and therefore, must be connected to a ground plane with thermal vias to allow heat to dissipate from the device. thermal properties of the ic package are given in table 1. selecting the output voltage (max8902a) the max8902a output can be set to one of nine volt- ages by shorting or opening the sela and selb inputs, as shown in table 2. sela and selb should be connected to gnd, in, or left unconnected. alternatively, they may be driven high, low, or open with external logic; however, the states of sela and selb are sampled only at startup. the regulation voltage can be set to a different level by cycling en or in momen- tarily to gnd. setting the output voltage (max8902b) the max8902b uses external feedback resistors to set the output regulation voltage as shown in figure 3. the output can be set from 0.6v to 5.3v. set the lower feed- back resistor (r2) to 120k or less to minimize fb input bias current error. then calculate the value of the upper feedback resistor (r1) as follows: where v fb is the feedback regulation voltage of 0.6v. power-ok (max8902b) the max8902b includes an additional open-drain out- put, pok , that pulls low to indicate the output voltage is in regulation. during startup, pok is high impedance until the output voltage rises to 91% of its regulation level. if an overload occurs at the output, or the output is shut down, pok is high impedance. rr v v out fb 12 1 = ? ? ? ? ? ? ? continuous power dissipation 953.5mw derate 11.9mw/c above +70c ja * 83.9c/w jc 10.8c/w table 1. 2mm x 2mm tdfn package thermal characteristics output voltage (v) sela state selb state 1.5 in unconnected 1.8 unconnected gnd 2.0 unconnected in 2.5 unconnected unconnected 3.0 gnd gnd 3.1 gnd in 3.3 gnd unconnected 4.6 in gnd 4.7 in in table 2. max8902a output voltages * ja is specified according to the jesd51 standard with the part mounted on a multilayer pcb.
input capacitor a 10? ceramic capacitor is recommended for the input. select a capacitor that maintains its capacitance over temperature and dc bias. capacitors with x5r or x7r temperature characteristics generally perform well. output capacitor a minimum of 10? of capacitance is required at out to ensure stability. select a ceramic capacitor that maintains its capacitance over temperature and dc bias. capacitors with x5r or x7r temperature charac- teristics generally perform well. max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package maxim integrated | 8 www.maximintegrated.com in en out byp on off output 4.6v selb sela outs gnd ep 10 f input 4.7v to 5.5v 0.01 f 10 f max8902a figure 2. max8902a fixed-output application circuit in en out byp on off output adjustable 0.6v to 5.3v gs pok fb gnd ep 10 f input 1.7v to 5.5v 0.01 f 10 f max8902b r1 r2 logic supply r3 100k to c figure 3. max8902b adjustable-output application circuit chip information process: bicmos tdfn (2mm x 2mm) top view 1 2 8 7 3 4 6 5 outs selb sela out byp gnd en in max8902a tdfn (2mm x 2mm) 1 2 8 7 3 4 6 5 fb pok gs out byp gnd en in max8902b ep + ep + ep = exposed paddle. pin configurations package type package code outline no. land pattern no. 8 tdfn-ep t822+1 21-0168 90-0064 package information for the latest package outline information and land patterns (foot- prints), 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.
maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integr ated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and specifications without notice 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. 2015 maxim integrated products , inc. | 9 max8902a/max8902b low-noise 500ma ldo regulators in a 2mm x 2mm tdfn package for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds web site at www.maximintegrated.com. revision history revision number revision date description pages changed 0 9/07 initial release 1 1/08 changed input capacitor value from 4.7? to 10? 1, 5, 8 2 2/08 changed bp to byp 2, 4? 3 5/08 updated toc 5 title 4 4 4/11 added the max8902bata/v+ part to the ordering information table 1 5 10/12 updated jc specification in table 1 7 6 1/15 added max8902aata/v+ to ordering information 1
|
