L6917B STMicroelectronics, L6917B Datasheet
L6917B
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L6917B Summary of contents
Page 1
... CURRENT < > CH2 OVER CURRENT CH1 OVER CURRENT CH 2 OVER CURRENT + IFB - PWM2 ERROR AMPLIFIER Vcc VSEN FB COMP Vcc L6917B SO-28 L6917BDTR (Tape & Reel) VCCDR BOOT1 UGATE1 HS PHASE1 LGATE1 LS ISEN1 CURRENT PGNDS1 READING PGND PGNDS2 CURRENT READING ISEN2 LGATE2 LS PHASE2 UGATE2 ...
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... L6917B ABSOLUTE MAXIMUM RATINGS Symbol Vcc PGND CCDR V -V Boot Voltage BOOT PHASE V -V UGATE1 PHASE1 V -V UGATE2 PHASE2 LGATE1, PHASE1, LGATE2, PHASE2 to PGND All other pins to PGND V Sustainable Peak Voltage t < 20ns @ 600kHz phase THERMAL DATA Symbol R Thermal Resistance Junction to Ambient ...
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... OSC = OPEN OSC = OPEN; Tj 125 GND=74k T I =5mA SINK OSC = OPEN OVP or UVP Active VID0, VID1, VID2, VID3, VID4 see Table1; FBR = V ; FBG = GND OUT VIDx = GND VIDx = OPEN COMP=10pF L6917B Min Typ Max Unit 7 0.5 1 1 ...
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... L6917B ELECTRICAL CHARACTERISTICS (continued 12V ±10 70°C unless otherwise specified CC J Symbol Parameter Input Offset SR Slew Rate DIFFERENTIAL CURRENT SENSING I , Bias Current ISEN1 I ISEN2 I Bias Current PGNDSx I , Bias Current at ISEN1 Over Current Threshold I ISEN2 I Active Droop Current FB GATE DRIVERS ...
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... L6917B VID0 Output Voltage (V) 1 OUTPUT OFF 0 1.100 1 1.125 0 1.150 1 1.175 0 1.200 1 1.225 0 1.250 1 1.275 0 1.300 1 1.325 0 1.350 1 1.375 0 1.400 1 1.425 0 1.450 1 1.475 0 1 ...
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... L6917B PIN FUNCTION N Name 1 LGATE1 Channel 1 low side gate driver output. 2 VCCDR Mosfet driver supply. It can be varied from 5V to 12V. 3 PHASE1 This pin is connected to the source of the upper mosfet and provides the return path for the high side driver of channel 1. 4 UGATE1 Channel 1 high side gate driver output. ...
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... Description This pin has to be connected to the low-side mosfet drain or ON -------------------------- nse 6 14. 300KHz + ----------------------------- 12. 300KHz – ----------------------------- L6917B 7/33 ...
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... L6917B Device Description The device is an integrated circuit realized in BCD technology. It provides complete control logic and protections for a high performance dual-phase step-down DC-DC converter optimized for microprocessor power supply designed to drive N Channel MOSFETs in a dual-phase synchronous-rectified buck topology. A 180 deg phase shift is provided between the two phases allowing reduction in the input capacitor current ripple, reducing also the size and the losses. The output voltage of the converter can be precisely regulated, programming the VID pins, from 1.100V to 1.850V with 25mV binary steps, with a maximum tolerance of ± ...
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... Figure 2. Soft Start CCDR V LGATEx V OUT PGOOD 2048 Clock Cycles Timing Diagram CCDR and VCCDR pins are not above their own turn-on thresholds. Dur- CC Turn ON threshold Acquisition: CH1 = PGOOD; CH2 = V L6917B reaches 2V (independently by Vcc value) ; CH4 = LGATEx OUT 9/33 ...
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... L6917B Driver Section The integrated high-current drivers allow using different types of power MOS (also multiple MOS to reduce the RDSON), maintaining fast switching transition. The drivers for the high-side mosfets use BOOTx pins for supply and PHASEx pins for return. The drivers for the low-side mosfets use VCCDRV pin for supply and PGND pin for return ...
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... INFO1 INFO2 ) for each phase, which has to be placed at one half LIM LIM = -------------------------- - Rg = ------------------------------------- R SENSE LGATEX Rg ISENX I ISENx Rg PGNDSX INFO x is the current carried by each PHASE = I FB INFO1 is then compared to I INFOX R SENSE 35 A L6917B + I ) INFO2 AVG 11/33 ...
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... L6917B current (I >35 A): the device enters in Quasi-Constant-Current operation. The low-side mosfets stays ON INFOx until I becomes lower than 35 A skipping clock cycles. The high side mosfets can be turned ON with a T INFO imposed by the control loop at the next available clock cycle and the device works in the usual way until another OCP event is detected ...
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... OUT SENSE V VID R --------------------- - I = – OUT MAX V MIN R FB COMP PROG = I FB INFO1 = +R · POSITIVE_OC_THRESHOLD L6917B OUT ESR DROP (b) To VOUT + I ) and the OC threshold, INFO2 = +R · < current is INFOx ) INFOx V DROOP 13/33 ...
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... L6917B Output Voltage Protection and Power Good The output voltage is monitored by pin VSEN not within +12/-10% (typ.) of the programmed value, the powergood output is forced low. Power good is an open drain output and it is enabled only after the soft start is finished (2048 clock cycles after start-up). ...
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... P = ESR · ESR OUT OUT 2 I OUT V = --------------------------------------------------------------------------------------------- OUT OUT INM – IN OUT OUT L = ----------------------------- - -------------- - the input voltage and – OUT IN is the output voltage. OUT L6917B 15/33 ...
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... Figure 9. Inductor ripple current vs V MAIN CONTROL LOOP The L6917B control loop is composed by the Current Sharing control loop and the Average Current Mode con- trol loop. Each loop gives, with a proper gain, the correction to the PWM in order to minimize the error in its regulation: the Current Sharing control loop equalize the currents in the inductors while the Average Current Mode control loop fixes the output voltage equal to the reference programmed by VID ...
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... ESR) and the applied P load Ro; I 2mV RE AD ------------------- - = --------------------------------------- - SENSE M AX PWM1 CURRENT 1/5 SHARING DUTY CYCLE CORRECTION 1/5 PWM2 D02IN1393 PWM DROOP s = -------------------------------------------------------------------------------------------------------------------- -------------- - /2). MAX INFO2 I INFO1 OUT + ----------- - L6917B ) is AVG 17/33 ...
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... L6917B – Z (s) is the compensation network impedance; F – Z (s) is the parallel of the two inductor impedance; L – A(s) is the error amplifier gain – PWM = -- - ------------------ - · is the ACM PWM transfer function where DVosc is the oscillator ramp amplitude and has a typical value of 2V ...
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... The distance from drivers and mosfet gates should be reduced as much as possible. Propagation delay times L ------------------------------------------------------- - ESR DROOP BOOTx PHASEx L C OUT VCC LOAD SGND b. PCB small signal components placement ------------------- - BOOTx OUT VCC L6917B LOAD 19/33 ...
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... L6917B as well as for the voltage spikes generated by the distributed inductance along the copper traces are so mini- mized. In fact, the further the mosfet is from the device, the longer is the interconnecting gate trace and as a conse- quence, the higher are the voltage spikes corresponding to the gate pwm rising and falling signals. Even if these spikes are clamped by inherent internal diodes, propagation delays, noise and potential causes of instabilities are introduced jeopardizing good system behavior ...
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... Demo board schematic circuit is reported in Figure 16. To PHASE connection ; 1.7V ; 45A IN OUT ; VRM 9.0 Output; 50A 35A IN OUT CORRECT To LS Drain and Source To HS Gate and Source 2 PACK mosfets for the low side switch in order L6917B 21/33 ...
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... BOOT1 BOOT2 5 24 UGATE1 UGATE2 4 25 R14 R15 PHASE1 PHASE2 3 26 R18 R17 LGATE1 LGATE2 1 27 R12 R13 ISEN1 ISEN2 PGNDS1 L6917B PGNDS2 PGND 28 VID4 22 PGOOD 23 VID3 21 VSEN 10 VID2 20 VID1 19 VID0 OSC / INH SGND 7 COMP ...
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... Vcc = 12V HS Drains = 5V HS Supply = 12V DZ1 JP6 JP2 JP1 VCCDR (LS Supply) = 12V = VCCDR =12V BOOTx Vcc = 12V HS Drains = 12V HS Supply = 12V DZ1 JP6 JP2 JP1 VCCDR (LS Supply) = 12V = VCCDR = 12V CC IN BOOTx L6917B depending = 5V IN 23/33 ...
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... L6917B PCB and Components Layouts Figure 20. PCB and Components Layouts Component Side Figure 21. PCB and Components Layouts Internal SGND Plane 24/33 Internal PGND Plane Solder Side ...
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... Fsw 5 12 300000 max ESR) has been used implementing a resulting ESR of 2.4m = 108mV after a 45A load transient. L 1.43k 20k 2 = ---------------------- ESR DRO 2200 ------ - ---------------------------------------- - = 15 nF 6.2k considering the temperature 5.9k (R3 to R6) (R7 (L1, L2) 1 ------------------------------------------------------------------ - = 9.1m 2 ------------- 1.43k + 2.4m 5.9k (C2) L6917B (R8) 6200 25/33 ...
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... C5, C6 C8, C9, C10 10 C11, C12, C13 1800 / 16V C19 to C24 2200 / 6.3V L1 L6917B Q1, Q3 STB90NF03L Q2, Q4 STB70NF03L D1, D2 STPS340U D3, D4 1N4148 System Efficiency Figure 22 shows the demo board measured efficiency versus load current for different values of input voltage. Mosfet temperature is always lower than 115 ° Figure 22. Efficiency (f = 200kHz ...
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... C11..C13 R19 C14, Q3 C23 D2 R20 Q3a R1 Ra JP3 Ca JP4 JP5 C1 R9 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 L6917B VoutCORE GNDCORE PGOOD FBG FBR 27/33 ...
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... C5, C6, C7 C9, C10 10 C11 to C13 1800 / 16V C14 to C23 2200 / 6.3V Ca 68n L1, L2 0.5 U1 L6917B Q1,Q1a, Q3,Q3a SUB85N03-04P Q2, Q4 SUB70N03-09BP D1, D2 STPS340U D3, D4 1N4148 Efficiency Figure 24 showes the system efficiency for output current ranging form 50A. Figure 24. Efficiency (f = 200kHz; Vout = 1.7V) osc ...
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... Figure 26 shows the system response from 0 to 50A load transient. To obtain such a response, 5 additional capacitors have been added to the output filter to reproduce the motherboard output filter. Noise can be further reduced by adding ceramic decoupling capacitors. Figure 26. 1.7V Output Voltage Ripple During 0 to 50A Load Transient L6917B 29/33 ...
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... C8 C7 BOOT1 BOOT2 5 24 UGATE1 UGATE2 4 25 R14 R15 PHASE1 PHASE2 3 26 R18 R17 LGATE1 LGATE2 1 27 R12 R13 ISEN1 ISEN2 L6917B PGNDS1 PGNDS2 PGND 28 VID4 22 PGOOD 23 VID3 21 VSEN 10 VID2 20 VID1 19 VID0 OSC / INH SGND 7 ...
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... SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 0805 SMD 1206 SMD 1206 Radial 10x10.5 Radial 10x23 SO28 2 D PACK SMB SOT23 Minimelf @ 1A/ s L6917B 31/33 ...
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... L6917B mm DIM. MIN. TYP. MAX. A 2.65 a1 0.1 0.3 0.004 b 0.35 0.49 0.014 b1 0.23 0.32 0.009 C 0 (typ.) D 17.7 18.1 0.697 E 10 10.65 0.394 e 1.27 e3 16.51 F 7.4 7.6 0.291 L 0.4 1.27 0.016 S 8 (max.) 32/33 inch MIN. TYP. MAX. 0.104 0.012 0.019 0.013 0.020 0.713 0.419 0.050 0.65 0.299 0.050 OUTLINE AND MECHANICAL DATA SO28 ...
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... STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco - Singapore - Spain 2002 STMicroelectronics - All Rights Reserved STMicroelectronics GROUP OF COMPANIES - Sweden - Switzerland - United Kingdom - U.S.A. http://www.st.com L6917B 33/33 ...