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SMB214A/B/C
High-power, Three-channel Programmable DC-DC System Power Managers
FEATURES & APPLICATIONS
* Digital programming of all major parameters via I2C interface and non-volatile memory * Output voltage set point * Input/battery voltage monitoring * Output power-up/down sequencing * Dynamic voltage control of all outputs * UV/OV monitoring of all outputs * Enable/Disable outputs independently * User friendly Graphical User Interface (GUI) * Three synchronous step-down output channels * Integrated RESET monitor * +2.7V to +6.0V Input Range * Highly accurate output voltage: <2.5% * Factory programmable dead times * 0% to 100% Duty Cycle operation * Undervoltage Lockout (UVLO) with hysteresis * Operating frequency: 400kHz (SMB214A), 800kHz (SMB214B), 1MHz (SMB214C) Preliminary Information
INTRODUCTION
The SMB214A/B/C are highly integrated and flexible threechannel power managers designed for use in a wide range of applications. The built-in digital programmability allows system designers to custom tailor the device to suit almost any multichannel power supply application from digital camcorders to set-top boxes. Complete with a user friendly GUI, all programmable settings, including output voltages and input/output voltage monitoring, can be customized with ease. The SMB214A/B/C integrate all the essential blocks required to implement a complete three-channel power subsystem consisting of three synchronous step-down "buck" controllers. Additionally sophisticated power control/monitoring functions required by complex systems are built-in. These include digitally programmable output voltage set point, powerup/down sequencing, enable/disable, dynamic voltage management and UV/OV monitoring on all channels. The integration of features and built-in flexibility of the SMB214A/B/C allows the system designer to create a "platform solution" that can be easily modified via software without major hardware changes. Combined with the re-programmability of the SMB214A/B/C, this facilitates rapid design cycles and proliferation from a base design to future product generations. The SMB214A/B/C are suited to a wide variety of applications with an input range of +2.7V to +6.0V. Higher input voltage operation can easily be implemented with a small number of external components. Output voltages are extremely accurate (<2.5%). Communication is accomplished via the industry standard I2C bus. All user-programmed settings are stored in non-volatile EEPROM. The devices are offered in both the commercial and the industrial operating temperature range. The package type is a lead-free, RoHS compliant, 5x5 QFN32.
Applications
* * * * * * Car & Marine Navigation Systems Set-top Boxes TVs DDR Memory Mobile Computing/PDAs Office Equipment * DMB Systems
SIMPLIFIED APPLICATIONS DRAWING
+2.7V to +6.0V or Li-Ion
SMB214
I2C/SMBus
Enable Input
System Control and Monitoring
+0.5V to Vin (Prog.) @ 5A
CPU Core
3 StepDown (Buck) Channels
+0.5V to Vin (Prog.) @ 5A
Memory, I/O
RESET Output (Power Good)
RESET Monitor
+0.5V to Vin (Prog.) @ 5A
Analog/RF
Figure 1 - Applications schematic featuring the SMB214A/B/C programmable DC-DC controllers. Note: This is an applications example only. Some pins, components and values are not shown.
(c) SUMMIT Microelectronics, Inc. 2007
757 N. Mary Avenue * Sunnyvale CA 94085 Phone 408 523-1000 * FAX 408 523-1266
http://www.summitmicro.com/
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SMB214A/B/C
Preliminary Information
GENERAL DESCRIPTION
The SMB214A/B/C are fully programmable DC-DC controllers that incorporate power delivery and advanced power monitoring and control functionality. The devices integrate three synchronous "buck" stepdown controllers in a space saving 5x5 QFN-32 package. The SMB214A uses a fixed 400kHz whereas the SMB214B uses a fixed 800kHz, and the SMB214C a fixed 1MHz Pulse Width Modulation (PWM) control circuit. A type-three voltage mode compensation network is used offering a cost effective solution without compromising transient response performance. By utilizing external N- and P-type MOSFET transistors the efficiency and load current level can be customized to fit a wide array of system requirements. The SMB214A/B/C contain three buck outputs capable of producing an output voltage less than the input voltage. Each buck output voltage is set by an internal resistor divider and a programmable voltage reference. The integrated resistor divider eliminates the cost and space necessary for external components and has several programmable values. Through the programmability of the reference and the resistor divider, practically any output voltage smaller than the battery can be produced without the need to change external components. The SMB214A/B/C are capable of power-on/off cascade sequencing where each channel can be assigned one of three unique sequence positions. During sequencing each channel in a given sequencing position is guaranteed to reach its programmed output voltage before the channel(s) occupying the next sequence position initiate their respective soft-start sequence. A unique programmable delay exists between each power on/off sequence position. In addition to power on/off sequencing all supplies can be 2 powered on/off individually through an I C command or by assertion of the enable pin. Each output voltage is monitored for under-voltage and over-voltage (UV/OV) conditions, using a comparatorbased circuit where the output voltage is compared against an internal programmable reference. An additional feature of the output voltage monitoring is a programmable glitch filter capable of digitally filtering a transient OV/UV fault condition from a true system error. When a fault is detected for a period in excess of the glitch filter, all supplies may be sequenced down or immediately disabled and an output status pin can be asserted. The current system status is always accessible via internal registers containing the status of all three channels. The SMB214A/B/C also possess an Under-voltage Lockout (UVLO) circuit to ensure the devices will not power up until the input voltage has reached a safe operating voltage. The UVLO function exhibits hysteresis, ensuring that noise or a brown out voltage on the supply rail does not inadvertently lead to a system failure. The SMB214A/B/C provide dynamic voltage management over all of their output voltages. Through 2 an I C command, all output voltage levels can be increased or decreased to a pre-programmed level. In addition, each output is slew rate limited by soft-start circuitry that requires no external capacitors. All programmable settings on the SMB214A/B/C are stored in non-volatile registers and are easily accessed and modified over an industry standard I2C serial bus. For fastest prototype development times Summit offers an evaluation card and a Graphical User Interface (GUI).
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SMB214A/B/C
TYPICAL APPLICATION
VIN: +2.7V to +6.0V
SMB214A/B/C
VBATT VDDCAP GND HSDRV_CH2 +0.8V to VIN @ 5A HVSUP2
LSDRV_CH2 SDA SCL PWREN HOST_ RESET HEALTHY/ nRESET VM_CH2 COMP1_CH2 COMP2_CH2
HVSUP1 HSDRV_CH1
HVSUP0 HSDRV_CH0 +0.8V to VIN @ 5A LSDRV_CH1
+0.8V to VIN @ 5A
LSDRV_CH0
VM_CH1 COMP1_CH1
VM_CH0 COMP1_CH0 COMP2_CH0
COMP2_CH1
Figure 2 - Typical application schematic
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SMB214A/B/C
INTERNAL BLOCK DIAGRAM
COMP2_CH[0,1,2] VM_CH[0,1,2]
100k - + OA + - CLAMP MAX LIMIT LOW LIMIT DUTY CYCLE LIMIT OSC
Fixed 400/800/ 1000kHz
Channel 0,1,2 Synchronous buck PWM Converter
HVSUP[0,1,2] HSDRV[0,1,2]
I2C/SMBUS SDA SCL COMP1_CH[0,1,2]
VREF LEVEL SHIFTER DIGITAL TO VDDCAP ANALOG CONVERTER VREF
DEADTIME
+ -
GLITCH FILTER
OVER VOLTAGE DETECTION
LSDRV[0,1,2]
SEQUENCING AND MONITORING LOGIC ENABLE
PWREN
+ -
GLITCH FILTER
UNDER VOLTAGE DETECTION
VBATT
GND
BANDGAP
VREF
VDD_CAP
2.5V REGULATOR
+ -
UV2
D Q
LEVEL SHIFTER VREF
+ -
UV1
Figure 3 -SMB214A/B/C internal block diagram. Programmable functional blocks include: level shifters, digital to analog converter and the VM_CH[0,1,2] voltage dividers.
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SMB214A/B/C
PIN DESCRIPTION
Pin Number Pin Type Pin Name Pin Description The HSDRV_CH0 (Channel 0 High-side Driver) pin is the upper switching node of the channel 0 synchronous step-down buck controller. Attach to the gate of p-channel MOSFET. A delay exists between the assertion of HSDRV_CH0 and assertion of LSDRV_CH0 to prevent excessive current flow during switching. The HEALTHY pin is an open drain output. High when all enabled output supplies are within the programmed levels. HEALTHY will ignore any disabled supply. There is a programmable glitch filter on the under-voltage and over-voltage sensors so that short transients outside of the limits will be ignored by HEALTHY. This pin can also be programmed to act as a Reset Output (nRESET). In this case, it releases with a programmable delay after all outputs are valid. When used, this pin should be pulled high by an external pull-up resistor. The COMP1_CH0 (Channel 0 primary Compensation) pin is the primary feedback input of the channel 0 step-down buck controller. The COMP1_CH0 pin is internally connected to a programmable resistor divider. The COMP2_CH0 (Channel 0 secondary Compensation) pin is the secondary feedback input of the channel 0 step-down buck controller. The VM_CH0 (Channel 0 Voltage Monitor) pin connects the channel 0 step-down controller output. Internally the VM_CH0 pin connects to a programmable resistor divider. SDA (Serial Data) is an open drain bi-directional pin used as the I2C data line. SDA must be tied high through a pull-up resistor. SCL (Serial Clock) is an open drain input pin used as the I2C clock line. SCL must be tied high through a pull-up resistor. The LSDRV_CH1 (Channel 1 Low-side Driver) pin is the lower switching node of the channel 1 synchronous step-down buck controller. Attach to the gate of n-channel MOSFET. Channel 1 High Voltage Supply for Channel 1 buck driver. The HSDRV_CH1 (Channel 1 High-side Driver) pin is the upper switching node of the channel 1 synchronous step-down buck controller. Attach to the gate of p-channel MOSFET. A delay exists between the assertion of HSDRV_CH1 and assertion of LSDRV_CH1 to prevent excessive current flow during switching. The HOST_RESET pin is an active high reset input. When this pin is asserted high, the nRESET output will immediately go low. When HOST_RESET is brought low, nRESET will go high after a programmed reset delay. When pin 2 is used as a HEALTHY output, this pin needs to be attached to GND or VBATT via a resistor. The COMP1_CH1 (Channel 1 primary Compensation) pin is the primary compensation input of the channel 1 step-down buck controller. The COMP1_CH1 pin is internally connected to a programmable resistor divider. The COMP2_CH1 (Channel 1 secondary Compensation) pin is the secondary compensation input of the channel 1 step-down buck controller.
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1
OUT
HSDRV_CH0
2
OUT
HEALTHY (nRESET)
3
IN
COMP1_CH0
4 5 6 7 8 9
IN IN I/O IN OUT PWR
COMP2_CH0 VM_CH0 SDA SCL LSDRV_CH1 HVSUP1
10
OUT
HSDRV_CH1
11
IN
HOST_RESET
12
IN
COMP1_CH1
13
IN
COMP2_CH1
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SMB214A/B/C
PIN DESCRIPTION
Pin Number 14 15 16 17 18 Pin Type IN CAP PWR OUT PWR Pin Name VM_CH1 VDD_CAP VBATT LSDRV_CH2 HVSUP2 Pin Description The VM_CH1 (Channel 1 Voltage Monitor) pin connects the channel 1 step-down controller output. Internally the VM_CH1 pin connects to an internal programmable resistor divider. The VDD_CAP (VDD Capacitor) pin is an external capacitor input used to filter the internal supply. Power supply to part. The LSDRV_CH2 (Channel 2 Low-side Driver) pin is the lower switching node of the channel 2 synchronous step-down buck controller. Attaches to the gate of n-channel MOSFET. Channel 2 High Voltage Supply for Channel 2 buck driver. The HSDRV_CH2 (Channel 2 High-side Driver) pin is the upper switching node of the channel 2 synchronous step-down buck controller. Attach to the gate of p-channel MOSFET. A delay exists between the assertion of HSDRV_CH2 and assertion of LSDRV_CH2 to prevent excessive current flow during switching. The COMP2_CH2 (Channel 2 secondary Compensation) pin is the secondary compensation input of the channel 2 step-down buck controller. The COMP1_CH2 (Channel 2 primary Compensation) pin is the primary compensation input of the channel 2 step-down buck controller. Each pin is internally connected to a programmable resistor divider. The VM_CH2 (Channel 2 Voltage Monitor) pin connects the channel 6 step-down controller output. Internally the VM_CH2 pin connects to an internal programmable resistor divider. The PWREN (Power Enable) pin is a programmable input used to enable (disable) selected supplies. This pin can also be programmed to latch and act as a debounced, manual push button input. Active high when level triggered, active low when used as a push- button input. When unused this pin should be tied to a solid logic level. Ground The LSDRV_CH0 (Channel 0 Low-side Driver) pin is the lower switching node of the channel 0 synchronous step-down buck controller. Attach to the gate of n-channel MOSFET. Channel 0 High Voltage Supply used to power the channel 0 buck driver. Exposed metal (thermal) Pad on bottom of SMB214A/B/C. The thermal pad of the QFN package must be connected to the PCB GND. No Connect
19
OUT
HSDRV_CH2
20
IN
COMP2_CH2
21
IN
COMP1_CH2
22
IN
VM_CH2
26
IN
PWREN
30 31 32 PAD 23, 24, 25, 27, 28, 29
PWR OUT PWR PWR N/C
GND LSDRV_CH0 HVSUP0 GND N/C
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SMB214A/B/C
PACKAGE AND PIN DESCRIPTION
Top View SMB214A/B/C 5mm x 5mm QFN-32
32
31
30
29
28
27
26
25
1 2 3 4 5 6 7 8
24 23 22 21 20 19 18 17
9
10
11
12
13
14
15
16
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SMB214A/B/C
ABSOLUTE MAXIMUM RATINGS Temperature Under Bias .................... -55C to +125C Storage Temperature.......................... -65C to +150C Terminal Voltage with Respect to GND: VBATT Supply Voltage .................... -0.3V to +10V HVSUP Supply Voltage .................. -0.3V to +6.5V All Others ...................................... -0.3V to VBATT Output Short Circuit Current .............................100mA Reflow Solder Temperature (30 secs)............... +260C Junction Temperature........................................ +150C ESD Rating per JEDEC ..................................... +2000V Latch-Up testing per JEDEC............................. 100mA RECOMMENDED OPERATING CONDITIONS Commercial Temperature Range............... 0C to +70C Industrial Temperature Range ................ -40C to +85C VBATT Supply Voltage ........................... +2.7V to +6.0V HVSUP Supply Voltage........................... +2.7V to +6.0V All Others.................................................GND to VBATT Package Thermal Resistance (JA), 32-Lead QFN (thermal pad connected to PCB)....................... 37.2C/W Moisture Classification Level 3 (MSL 3) per J-STD-020 RELIABILITY CHARACTERISTICS Data Retention ................................................ 100 Years Endurance ................................................ 100,000 Cycle Temperature Range ................................ -40C to +85C
Note - The device is not guaranteed to function outside its operating rating. Stresses 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 outside those listed in the operational sections of the specification is not implied. Exposure to any absolute maximum rating for extended periods may affect device performance and reliability.
DC OPERATING CHARACTERISTICS
(Over recommended operating conditions, unless otherwise noted. All voltages are relative to GND.) Symbol Parameter Conditions Min Typ Max VBATT VHVSUP VUVLO IDD-MONITOR IDD-ACTIVE VDD_CAP Oscillator SMB214A fOSC Oscillator frequency SMB214B SMB214C OPP LT fSV fST Oscillator peak-to-peak Frequency stability for voltage Frequency stability for temperature +25C to +70C, fOSC = 800kHz +25C to +85C, fOSC = 800kHz 320 640 800 400 800 1000 1 0.1 0.18 0.22 480 960 1200 V %/V kHz/ C kHz Input supply voltage Buck driver supply voltage Under-voltage lockout Monitoring current Active current Internal supply, present on VDD_CAP pin Input supply voltage (operational) Gate drive voltage VBATT rising VBATT falling All voltage inputs monitored. No supplies switching, VBATT at 4.2V. Total current all channels enabled. No load. VBATT at 4.2V. Note 2. No load 2.4 1.9 2.7 2.7 2.2 2.0 290 1.2 2.5 400 2.0 2.6 6.0 6.0 2.3 Unit V V V V A mA V
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SMB214A/B/C
DC OPERATING CHARACTERISTICS (CONTINUED)
(Over recommended operating conditions, unless otherwise noted. All voltages are relative to GND.) Symbol Parameter Conditions Min Typ Max Error Amplifier AVOL BW ISOURCE ISINK Open loop voltage Gain Frequency bandwidth Output source current Output sink current At DC At AVOL = 0 dB At 0.5V At 0.5V 60 30 20 800 Unit dB MHz A A
Output Block VOUT Voltage set point range. 100% Maximum Duty cycle VBATT= 4.2V, ILOAD=0 VOUT = VBATT x (duty cycle) VBATT= 6.0V, ILOAD=0 VOUT = VBATT x (duty cycle) Commercial temperature range Industrial temperature range Output high Output low Output high Output low COMP1 pin Programmable in 4mV steps High Duty Cycle Low Duty Cycle High Duty Cycle Low Duty Cycle
0.7 x VDD_CAP
0.5 0.5 -2.5 -2.5 2 2 2 2 1.0 100 35 70 0
4.2 V 6.0 +2.5 +2.5 %
VOUT
Output accuracy, Note 1
RDRVH
HSDRV ON resistance
RDRVL VCOMP1
LSDRV ON resistance Feedback voltage reference 100% Max Duty Cycle
V
D.C. 90% Max Duty Cycle Logic Levels VIH VIL VOL Input high voltage Input low Open drain outputs
%
6.0
0.3 x VDD_CAP
V V V
0 ISINK = 1mA 0
0.4
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SMB214A/B/C
DC OPERATING CHARACTERISTICS (CONTINUED)
(Over recommended operating conditions, unless otherwise noted. All voltages are relative to GND.) Symbol Parameter Conditions Programmable UV1 threshold voltage measured on VBATT pin in 150 mV increments Programmable UV2 threshold voltage measured on VBATT pin in 150 mV increments Min Typ Max Unit Programmable Monitoring Thresholds VPUV1 VPUV2 VPUV2 VPUV1 Programmable UV1 threshold Programmable UV2 threshold UV2 accuracy UV1 accuracy 2.55 2.55 2 2 -5 PUVTH Programmable under-voltage threshold Output voltage relative to nominal operating voltage. Note 3. -10 -15 -20 +5 POVTH Programmable over-voltage threshold Output voltage relative to nominal operating voltage. Note 3. +10 +15 +20
Note 1: Voltage accuracies are only guaranteed for factory-programmed settings. Changing the output voltage from that reflected in the customer specific CSIR code might result in inaccuracies exceeding those specified above by 1%. Note 2: For more accurate active current levels under several load conditions, Summit's proprietary design software can be used. Contact the factory for more information. Note 3: Guaranteed by Design and Characterization - not 100% tested in Production.
3.60 3.60
V V % %
%
%
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SMB214A/B/C
AC OPERATING CHARACTERISTICS
(Over recommended operating conditions, unless otherwise noted. All voltages are relative to GND.) Note 4 Symbol Description Conditions Min Typ Max Unit 1.5 12.5 Programmable power-On Programmable power-on sequence tPPTO ms sequence timeout period. position to sequence position delay. 25 50 1.5 12.5 Programmable power-off Programmable power-off sequence tDPOFF ms sequence timeout period. position to sequence position delay. 25 50 Time between active enable in which OFF corresponding outputs must exceed there 50 Programmable sequence programmed under voltage threshold. If tPST ms termination period 100 exceeded, a force shutdown will be 200 initiated. 0 Period for which fault must persist before Programmable glitch filter tPGF s fault triggered actions are taken. 8 25 Applicable when HEALTHY pin is used as 50 an nRESET output pin. Programmable Reset timeout period tRESET ms time following assertion of last supply 100 before nRESET pin is released high. 200 400 200 100 67 Programmable slew rate Adjustable slew rate factor proportional to SRREF V/s reference output slew rate. 50 33 25 20 Channels 0 to 2 tRL tFL tRL tFL tDT LS Driver output rise time LS Driver output fall time HS Driver output rise time HS Driver output fall time Driver non-overlap delay CG=100pF, VBATT=4.2V CG=100pF, VBATT=4.2V CG=100pF, VBATT=4.2V CG=100pF, VBATT=4.2V High to low transition on HSDRV Low to high transition on buck HSDRV 4.2 4.2 2.9 2.9 30 60 ns ns ns ns ns
Note 4: Timing specifications are 20% shorter for the SMB214C device and 60% longer for SMB214A.
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SMB214A/B/C
I2C-2 WIRE SERIAL INTERFACE AC OPERATING CHARACTERISTICS - 100 kHz
(Over recommended operating conditions, unless otherwise noted. All voltages are relative to GND.) 100kHz Symbol Description Conditions Min Typ Max Units fSCL TLOW THIGH tBUF tSU:STA tHD:STA tSU:STO tAA tDH tR tF tSU:DAT tHD:DAT TI tWR_CONFIG tWR_EE SCL clock frequency Clock low period Clock high period Bus free time Start condition setup time Start condition hold time Stop condition setup time Clock edge to data valid Data output hold time SCL and SDA rise time SCL and SDA fall time Data in setup time Data in hold time Noise filter SCL and SDA Write cycle time config Write cycle time EE Noise suppression Configuration registers Memory array SCL low to valid SDA (cycle n) SCL low (cycle n+1) to SDA change Note 5 Note 5 250 0 136 10 5 Before new transmission - Note 5 0 4.7 4.0 4.7 4.7 4.0 4.7 0.2 0.2 1000 300 3.5 100 kHz s s s s s s s s ns ns ns ns ns ms ms
Note 5: Guaranteed by Design.
TIMING DIAGRAMS
tR SCL tSU:STA SDA (IN) tAA SDA (OUT) tDH tHD:STA tHD:DAT tSU:DAT tSU:STO tF tHIGH tWR (For Write Operation Only) tLOW tBUF
Figure 4 - I2C timing diagram
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SMB214B EFFICIENCY GRAPHS
Efficiency at 3.3V
100 95
100 95
Efficiency at 2.5V
Efficiency (%)
90 85 80 75
Efficiency (%)
90 85 80 75 70 65 60 0 0.5 1 1.5
5.0V
70 65 60 0 0.5 1 1.5
4.2V 3.8V 3.6V 3.4V
2
5.0V 4.2V 3.8V 3.6V 3.3V 3.0V
2
Current (Amps)
100 95
Efficiency at 1.8V
C urrent (A ps) m
Efficiency (%)
90 85 80 75 70 65 60
5.0V 4.2V 3.8V 3.6V 3.3V 3.0V
0 0.5 1 1.5
100 95
Efficiency at 1.5V
100 95
2
C rren (A p u t m s)
Efficiency (%)
Efficiency at 1.2V
Efficiency (%)
90 85 80 75 70 65 60 0 0.5 1 1.5
90 85 80 75 70 65 60 0 0.5 1 1.5
5.0V 4.2V 3.8V 3.6V 3.3V 3.0V
2
5.0V 3.8V 4.2V 3.6V 3.3V 3.0V
2
C rren (A p u t m s)
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Current (Amps)
13
SMB214A/B/C
SMB214A EFFICIENCY GRAPHS
Efficiency at 1.2V, 1.8V, 2.5V, 3.3V
100 90 80
Efficiency (%)
70 60 50 40 30 20 10 0 0 2 4 Vin = 5.0 Volts 1.2V 1.8V 2.5V 3.3V
Current (Amps)
6
8
10
12
Buck 2.5V
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SMB214A/B/C
APPLICATIONS INFORMATION DEVICE OPERATION
POWER SUPPLY There are four supply input pins on the SMB214A/B/C: three HVSUP pins and the VBATT pin. Each supply must be powered from an input voltage between 2.76.0 volts. The HVSUP0 though HVSUP2 are used to power the HSDRV (PMOS driver) and LSDRV (NMOS driver) outputs. The rail-to-rail swing on the HSDRV and LSDRV pins is equal to the associated HVSUP supply voltage. The VBATT pin is internally regulated to 2.5V. This 2.5V supply is then filtered on the VDD_CAP pin and used to power all internal circuitry. The VBATT pin is monitored by an Under-Voltage Lockout (UVLO) circuit, which prevents the device from turning on when the voltage at this node is less than the UVLO threshold. OUTPUT VOLTAGE All output voltages on the SMB214A/B/C can be set via the non-volatile configuration registers. Each of the three step-down output voltages on the SMB214A/B/C can be adjusted for 100% duty cycle or 0% duty cycle operation. When 100% duty cycle mode is selected, the output voltage can be set up to the input voltage on the device, while the minimum output voltage is limited to the min duty cycle specification in the DC operating characteristics section. When the 0% duty cycle mode is selected, the maximum duty cycle is limited to the max duty cycle specification in the DC operating characteristics section. POWER-ON/OFF CONTROL Sequencing can be initiated: automatically, by a 2 volatile I C Power on command, or by asserting the PWREN pin. When the PWREN pin is programmed to initiate sequencing, it can be level or edge triggered. The PWREN input has a programmable de-bounce time of 100, 50, or 25ms. The de-bounce time can also be disabled. When configured as a push-button enable, PWREN must be asserted longer than the de-bounce time before sequencing can commence, and pulled low for the same period to disable the channels. ENABLE Each output can be enabled and disable by an enable signal. The enable signal is can be provided from either the PWREN pin or by the contents of the enable register. When enabling a channel from the enable register, the register contents default state must be set so that the output will be enabled or disabled following a POR (power on reset). The default state is programmable. CASCADE SEQUENCING Each channel on the SMB214A/B/C may be placed in any one of 3 unique sequence positions, as assigned by the configurable non-volatile register contents. The SMB214A/B/C navigate between each sequence position using a feedback-based cascade-sequencing circuit. Cascade sequencing is the process in which each channel is continually compared against a programmable reference voltage until the voltage on the monitored channel exceeds the reference voltage, at which point an internal sequence position counter is incremented and the next sequence position is entered. In the event that a channels enable input is not asserted when the channel is to be sequenced on, that sequence position will be skipped and the channel in the next sequence position will be enabled. POWER ON/OFF DELAY There is a programmable delay between when channels in subsequent sequence positions are enabled. The delay is programmable at 50, 25, 12.5 and 1.5ms intervals. This delay is programmable for each of the three sequence positions. MANUAL MODE The SMB214A/B/C provide a manual power-on mode in which each channel may be enabled individually irrespective of the state of other channels. In this mode, the enable signal has complete control over the channel, and all sequencing is ignored. In Manual mode, channels will not be disabled in the event of a UV/OV fault on any output or the VBATT pin. FORCE-SHUTDOWN When a battery fault occurs, a UV/OV is detected on 2 any output, or an I C force-shutdown command is issued, all channels will be immediately disabled, ignoring sequence positions or power off delay times. SEQUENCE TERMINATION TIMER At the beginning of each sequence position, an internal programmable timer will begin to time out. When this timer has expired, the SMB214A/B/C will automatically perform a force-shutdown operation. This timer is user programmable with a programmable sequence termination period (tPST) of 50, 100, 200 ms; this function can also be disabled.
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SMB214A/B/C
APPLICATIONS INFORMATION (CONTINUED)
POWER OFF SEQUENCING The SMB214A/B/C have a power-off sequencing operation. During a power off operation, the supplies will be powered off in the reverse order they where powered on in. During the power off sequencing, all enables are ignored. When a power-off command is issued the SMB214A/B/C will set the sequence position counter to the last sequence position and disable that channel without soft-start control; once off, the power off delay for the channel(s) in the next to last sequence position will begin to timeout, after which that channel(s) will be disabled. This process will continue until all channels have been disabled and are off. If a channel fails to turn off within the sequence termination period, the sequence termination timer will initiate a force shutdown, if enabled. INPUT AND OUTPUT MONITORING Both products monitor all outputs for under-voltage (UV) and over-voltage (OV) faults. The monitored levels are user programmable, and may be set at 5, 10, 15, and 20 percent of the nominal output voltage. The VBATT pin is monitored for two user programmable UV settings. The VBATT UV settings are programmable from 2.55V to 3.45V in 150mV increments. Once the UV/OV voltage set points have been violated, the SMB214A/B/C can be programmed to respond in one of three ways, perform: a power-off operation, a force-shutdown operation and-or it can trigger the nRESET/HEALTHY pin. DYNAMIC VOLTAGE MANAGEMENT In addition to the nominal voltage settings, the SMB214A/B/C have six additional voltage settings. These are ideal for situations where a core voltage needs to be reduced for power conservation. The dynamic voltage control settings have the same voltage range as the controllers' nominal output voltage. These settings are stored in the non-volatile configuration registers and can be set by a write to volatile configuration registers. The dynamic voltage control command registers contain bits for each channel that adjust the output voltages to one of the 7 set points after a volatile I2C write command.
When all channels are at their voltage setting, a bit is set in the dynamic voltage control status registers.
SOFT START The SMB214A/B/C provide a soft-start function for all PWM outputs. The soft-start control limits the slew rate that each output is allowed to ramp up without the need for an external capacitor.
Vout R2 R1
COMP1
VREF
+ -
Soft-Start Slew Rate=SRref* (1 + R2/R1) Vout= Vref* (1 + R2/R1)
Figure 5 - The output voltage is set by the voltage divider. The VREF voltage is programmable from 0 to 1.0 volt in 4mV increments via the I2C interface
HIGH VOLTAGE OPERATION While the SMB214 has a maximum input voltage of 6.0V, the controller can operate to much higher voltages by using the circuit shown in Figure 6. By inserting a capacitor (C1) in series with the HSDRV gate signal, the HSDRV pin is isolated from the 12V supply, and the AC coupling capacitor acts as a level translator transferring the 0-5V signal from the HSDRV pin to a 12V-to-7V (12V-5V=5V) signal at the gate of the PFET. When the gate stops switching, the capacitor becomes an open circuit, and the fate will be pulled high by R1, turning off the output. The schottky diode and the pull-up resistor are used for DC restoration and as a pull-up, respectively. Since the converter runs directly from the input supply (Example: 12V), the efficiency is consistent with that of a synchronous converter.
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SMB214A/B/C
APPLICATIONS INFORMATION (CONTINUED)
5V time C1 AC Coupling capacitor DC Restoration
12V 7V HSDRV time 0.1uF Schottky
All power comes directly from 12V supply Q2(P) +12V
Q6
R1
1K C28 22uF C33 0.1uF Q1(N) NP FDC6420C
L1 1 3.3uH C45 22uF C51 0.1uF Vout
LSDRV
Figure 6 - SMB214B circuit for enabling high-voltage operation.
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SMB214A/B/C
APPLICATIONS INFORMATION (CONTINUED)
Figure 7 - SMB214B applications schematic.
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SMB214A/B/C
APPLICATIONS INFORMATION (CONTINUED)
COMPONENT SELECTION Buck Outputs: Inductor: The starting point design of any and DC/DC converter is the selection of the appropriate inductor for the application. The optimal inductor value will set the inductor current at 30% of the maximum expected load current. The inductors current for a Buck converter is as follows: Buck: Equation 1: possible in order to minimize trace inductance that would otherwise limit the rate of change of the current. Output capacitor Each converter should have a high value low impedance output capacitor to act as a current reservoir for current transients and to. This capacitor should be either a X5R or X7R MLCC. For a Buck converter, the value of this capacitance is determined by the maximum expected transient current. Since the converter has a finite response time, during a load transient the current is provided by the output capacitor. Since the voltage across the capacitor drops proportionally to the capacitance, a higher output capacitor reduces the voltage drop until the feedback loop can react to increase the voltage to equilibrium. The voltage drop can be calculated according to: Equation 2:
L=
Vo(V IN - Vo) Vin * 0.3 * I MAX * f
Where Vo is the output voltage, VIN is the input voltage, f is the frequency, and IMAX is the max load current. For example: For a 1.2V output and a 3.6V input with a 500mA max load, and a 1MHz switching frequency the optimal inductor value is:
V=
I *T C
L=
1.2(3.6 - 1.2) = 5.3uH 3.6 * 0.3 * 0.5 * 1E 6
Choosing the nearest standard inductor value we select a 5.6uH inductor. It is important that the inductor has a saturation current level greater than 1.2 times the max load current. Other parameters of interest when selecting an inductor are the DCR (DC winding resistance). This has a direct impact on the efficiency of the converter. In general, the smaller the size of the inductor is the larger the resistance. As the DCR goes up the power loss increases according to the I2R relation. As a result choosing a correct inductor is often a trade off between size and efficiency. Input Capacitor Each converter should have a high value low impedance input (or bulk) capacitor to act as a current reservoir for the converter stage. This capacitor should be either a X5R or X7R MLCC (multi-layer-ceramic capacitor). The value of this capacitor is normally chosen to reflect the ratio of the input and output voltage with respect to the output capacitor. Typical values range from 2.2uF to 10uF. For Buck converters, the input capacitor supplies square wave current to the inductor and thus it is critical to place this capacitor as close to the PFET as
Where I is the load or transient current, T is the time the output capacitor is supporting the output and C is the output capacitance. Typical values range from 10uF to 44uF. Other important capacitor parameters include the Equivalent Series Resistance (E.S.R) of the capacitor. The ESR in conjunction with the ripple current determines the ripple voltage on the output, for typical values of MLCC the ESR ranges from 2-10m. In addition, carful attention must be paid to the voltage rating of the capacitor the voltage rating of a capacitor must never be exceeded. In addition, the DC bias voltage rating can reduce the measured capacitance by as much as 50% when the voltage is at half of the max rating, make sure to look at the DC bias de-rating curves when selecting a capacitor. MOSFETS When selecting the appropriate FET to use attention must be paid to the gate to source rating, input capacitance, and maximum power dissipation. Most FETs are specified by an on resistance (RDSON) for a given gate to source voltage (VGS). It is essential to ensure that the FETs used will always have a VGS voltage grater then the minimum value shown on the datasheet. It is worth noting that the specified VGS voltage must not be confused with the threshold voltage of the FET.
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SMB214A/B/C
APPLICATIONS INFORMATION (CONTINUED)
The input capacitance must be chosen such that the rise and fall times specified in the datasheet do not exceed ~5% of the switching period. To ensure the maximum load current will not exceed the power rating of the FET, the power dissipation of each FET must be determined. It is important to look at each FET individually and then add the power dissipation of complementary FETs after the power dissipation over one cycle has been determined. The Power dissipation can be approximated as follows: Equation 3: Equations 4, 5:
Buck - NFET : (1 - Buck - PFET :
VO ) *T VIN
VO *T VIN
P ~ R DSON * I L * TON
2
Where TON is the on time of the primary switch. TON can be calculated as follows:
Compensation: Summit provides a design tool to called Summit Power Designer" that will automatically calculate the compensation values for a design or allow the system to be customized for a particular application. The power designer software can be found at http://www.summitmicro.com/prod_select/xls/SummitP owerDesigner_Install.zip.
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SMB214A/B/C
DEVELOPMENT HARDWARE & SOFTWARE
The end user can obtain the Summit SMX3200 parallel port programming system or the I2C2USB (SMX3201) USB programming system for device prototype development. The SMX3200(1) system consist of a programming Dongle, cable and WindowsTM GUI software. It can be ordered on the website or from a local representative. The latest revisions of all software and an application brief describing the SMX3200 and SMX3202 are available from the website (http://www.summitmicro.com). The SMX3200 programming Dongle/cable interfaces directly between a PC's parallel port and the target application; while the SMX3202 interfaces directly to the PC's USB port and the target application. The device is then configured on-screen via an intuitive graphical user interface employing drop-down menus. The Windows GUI software will generate the data and send it in I2C serial bus format so that it can be directly downloaded to the SMB214A/B/C via the programming Dongle and cable. An example of the connection interface is shown in Figure 8. When design prototyping is complete, the software can generate a HEX data file that should be transmitted to Summit for approval. Summit will then assign a unique customer ID to the HEX code and program production devices before the final electrical test operations. This will ensure proper device operation in the end application.
Top view of straight 0.1" x 0.1 closed-side connector. SMX3200/SMX320 interface cable connector. Pin 9, 5.0V Pin 10, Reserved Pin 8, Reserved Pin 7, 10V Pin 5, Reserved Pin 6, MR# Pin 3, GND Pin 4, SDA Pin 2, SCL Pin 1, GND
VBATT
SMB214A/B/C
SDA SCL
10 8 6 4 2
9 7 5 3 1
0.1F
GND
Figure 8 - SMX3202 Programmer I2C serial bus connections to program the SMB214A/B/C.
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SMB214A/B/C
I2C PROGRAMMING INFORMATION
SERIAL INTERFACE Access to the configuration registers, general-purpose memory and command and status registers is carried out over an industry standard 2-wire serial interface (I2C). SDA is a bi-directional data line and SCL is a clock input. Data is clocked in on the rising edge of SCL and clocked out on the falling edge of SCL. All data transfers begin with the MSB. During data transfers, SDA must remain stable while SCL is high. Data is transferred in 8-bit packets with an intervening clock period in which an Acknowledge is provided by the device receiving data. The SCL high period (tHIGH) is used for generating Start and Stop conditions that precede and end most transactions on the serial bus. A high-to-low transition of SDA while SCL is high is considered a Start condition while a low-to-high transition of SDA while SCL is high is considered a Stop condition. The interface protocol allows operation of multiple devices and types of devices on a single bus through unique device addressing. The address byte is comprised of a 7-bit device type identifier (slave address). The remaining bit indicates either a read or a write operation. Refer to Table 1 for a description of the address bytes used by the SMB214A/B/C. The device type identifier for the memory array, the configuration registers and the command and status registers are accessible with the same slave address. The slave address can be can be programmed to any seven bit number 0000000BIN through 1111111BIN. WRITE Writing to the memory or a configuration register is illustrated in Figures 10 and 11. A Start condition followed by the slave address byte is provided by the host; the SMB214A/B/C respond with an Acknowledge; the host then responds by sending the memory address pointer or configuration register address pointer; the SMB214A/B/C respond with an acknowledge; the host then clocks in one byte of data. For memory and configuration register writes, up to 15 additional bytes of data can be clocked in by the host to write to consecutive addresses within the same page. After the last byte is clocked in and the host receives an Acknowledge, a Stop condition must be issued to initiate the nonvolatile write operation. READ The address pointer for the non-volatile configuration registers and memory registers as well as the volatile command and status registers must be set before data can be read from the SMB214A/B/C. This is accomplished by issuing a dummy write command, which is a write command that is not followed by a Stop condition. A dummy write command sets the address from which data is read. After the dummy write command is issued, a Start command followed by the address byte is sent from the host. The host then waits for an Acknowledge and then begins clocking data out of the slave device. The first byte read is data from the address pointer set during the dummy write command. Additional bytes can be clocked out of consecutive addresses with the host providing an Acknowledge after each byte. After the data is read from the desired registers, the read operation is terminated by the host holding SDA high during the Acknowledge clock cycle and then issuing a Stop condition. Refer to Figure 11 for an illustration of the read sequence. CONFIGURATION REGISTERS The configuration registers are grouped with the general-purpose memory. GENERAL-PURPOSE MEMORY The 96-byte general-purpose memory block is segmented into two continuous independently lockable blocks. The first 48-byte memory block begins at register address pointer A0HEX and the second memory block begins at the register address pointer C0HEX; see Table 1. Each memory block can be locked individually by writing to a dedicated register in the configuration memory space.
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SMB214A/B/C
I2C PROGRAMMING INFORMATION (CONTINUED)
GRAPHICAL USER INTERFACE (GUI) Device configuration utilizing the Windows based SMB214A/B/C graphical user interface (GUI) is highly recommended. The software is available from the Summit website (http://www.summitmicro.com ). Using the GUI in conjunction with this datasheet, simplifies the process of device prototyping and the interaction Slave Address 0000000BIN to 1111111BIN Register Type Configuration Registers are located in 00 HEX thru 9FHEX General-Purpose Memory Block 0 is located in A0 HEX thru BFHEX General-Purpose Memory Block 1 is located in C0 HEX thru FFHEX of the various functional blocks. A programming Dongle (SMX3202) is available from Summit to communicate with the SMB214A/B/C. The Dongle connects directly to the parallel port of a PC and programs the device through a cable using the I2C bus protocol. See figure 8 and the SMX3220 Data Sheet.
Table 1 - Possible address bytes used by the SMB214A/B/C.
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SMB214A/B/C
I2C PROGRAMMING INFORMATION (CONTINUED) S
M aster T A R T S A 3 Slave S A 2 S A 1 S A 0 Bus Address A 2 A 1 A 0 C 7 A C K C 6 Configuration Register Address C 5 C 4 C 3 C 2 C 1 C 0 A C K D 7 D 6 D 5 Data D 4 D 3 D 2 D 1 D 0 A C K S T O P
W
Figure 9 - Register Byte Write
S T A R T S A 3 Slave S A 2 S A 1 S A 0
M aster
Bus Address A 2 A 1 A 0 C 7 A C K C 6
Configuration Register Address C 5 C 4 C 3 C 2 C 1 C 0 A C K D 7 D 6 D 5
Data (1) D 4 D 3 D 2 D 1 D 0 A C K
W
M aster D 7 Slave D 6 D 5
Data (2) D 4 D 3 D 2 D 1 D 0 A C K D 7 D 6 D 5 D 2 D 1 D 0 A C K D 7 D 6 D 5
Data (16) D 4 D 3 D 2 D 1 D 0 A C K
S T O P
Figure 10 - Register Page Write
S T A R T S A 3 Slave S A 2 S A 1 S A 0 S T A R T C 1 C 0 A C K S A 3 S A 2 S A 1 S A 0
Master
Bus Address A 2 A 1 A 0 C 7 A C K C 6
Configuration Register Address W C 5 C 4 C 3 C 2
Bus Address A 2 A 1 A 0
R A C K
Master D 7 Slave D 6 D 5
Data (1) D 4 D 3 D 2 D 1 D 0 A C K D 7 D 6 D 5 D 2 D 1 D 0 A C K D 7 D 6 D 5
Data (n) D 4 D 3 D 2 D 1 D 0
N A C K
S T O P
Figure 11 - Register Read
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SMB214A/B/C
PACKAGE DIMENSIONS
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SMB214A/B/C
DEVICE MARKING
SUMMIT SMB214AN
Subject to change in production
Pin 1
Summit Part Number: SMB214A, SMB214B, or SMB214C
xx
Annn L AYYWW
Status Tracking Code (01, 02,...) (Summit Use)
Date Code (YYWW) Lot tracking code (Summit use) 100% Sn, RoHS compliant
Drawing not to scale
Part Number suffix (Contains Customer specific ordering requirements) Product Tracking Code (Summit use)
ORDERING INFORMATION
Summit Part Number Package
N = 32-Pad 5x5 QFN
SMB214A N
C
nnn
L
SMB214A, SMB214B, or SMB214C
Environmental Attribute L = 100% Sn, RoHS compliant Part Number Suffix
Specific requirements are contained in the suffix
Temperature Range
C = Commercial BLANK = Industrial
NOTICE
SUMMIT Microelectronics, Inc. reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. SUMMIT Microelectronics, Inc. assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained herein reflect representative operating parameters, and may vary depending upon a user's specific application. While the information in this publication has been carefully checked, SUMMIT Microelectronics, Inc. shall not be liable for any damages arising as a result of any error or omission. SUMMIT Microelectronics, Inc. does not recommend the use of any of its products in life support or aviation applications where the failure or malfunction of the product can reasonably be expected to cause any failure of either system or to significantly affect their safety or effectiveness. Products are not authorized for use in such applications unless SUMMIT Microelectronics, Inc. receives written assurances, to its satisfaction, that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; and (c) potential liability of SUMMIT Microelectronics, Inc. is adequately protected under the circumstances. Revision 2.0 This document supersedes all previous versions. Please check the Summit Microelectronics Inc. web site at http://www.summitmicro.com for data sheet updates. (c) Copyright 2008 SUMMIT MICROELECTRONICS, Inc. PROGRAMMABLE POWER FOR A GREEN PLANETTM TM is a registered trademark of Summit Microelectronics Inc., I2C is a trademark of Philips Corporation. ADOC
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