IRDC3847-P1V2 SupIRBuck TM USER GUIDE FOR IR3847 EVALUATION BOARD DESCRIPTION The IR3847 is a synchronous buck converter, providing a compact, high performance and flexible solution in a small 5mmx6mm QFN package. Key features offered by the IR3847 include internal Digital Soft Start, precision 0.6V reference voltage, Power Good, thermal protection, programmable switching frequency, Enable input, input under-voltage lockout for proper start-up, enhanced line/ load regulation with feed forward, external frequency synchronization with smooth clocking, internal LDO, true differential remote sensing and pre-bias start-up. A thermally compensated output over-current protection function is implemented by sensing the voltage developed across the on-resistance of the synchronous rectifier MOSFET for optimum cost and performance. This user guide contains the schematic and bill of materials for the IR3847 evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for IR3847 is available in the IR3847 data sheet. BOARD FEATURES * Vin = +12V (+ 13.2V Max), No Vcc required. * Vout = +1.2V @ 0- 25A * Fs=1000kHz * L= 0. 15uH * Cin= 5x22uF (ceramic 1206) + 1x330uF (electrolytic) * Cout=7x22uF (ceramic 0805) 2/13/2012 Confidential 1 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 CONNECTIONS and OPERATING INSTRUCTIONS A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum of 25A load should be connected to VOUT+ and VOUT-. The inputs and output connections of the board are listed in Table I. IR3847 needs only one input supply and internal LDO generates Vcc from Vin. If operation with external Vcc is required, then R33 should be removed and external Vcc can be applied between Vcc+ and Vcc- pins. Vin pin and Vcc pins should be shorted together for external Vcc operation by installing R35. This version of the demoboard was built with a previous revision of the IR3847 for which Vp was pin 14 and Vref was pin 15. However, in the new revision, these pins have been interchanged in order to allow easier bypass of the Vref pin. The consequence of this is that the Vp input on the board should be considered Vref and the Vref input on the board should be considered Vp. The board is configured for remote sensing. If local sense is desired, R8 should be uninstalled and R16 should be installed instead. External Enable signal can be applied to the board via exposed Enable pad and R18 should be removed for this purpose. Table I. Connections Connection 2/13/2012 Signal Name VIN+ Vin (+12V) VIN- Ground of Vin Vout+ Vout(+1.2V) Vout- Ground for Vout Vcc+ Vcc Pin Vcc- Ground for Vcc input Enable Enable PGood Power Good Signal AGnd Analog ground Confidential 2 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 CONNECTIONS and OPERATING INSTRUCTIONS LAYOUT The PCB is a 6-layer board. All of layers are 2 Oz. copper. The IR3847 and most of the passive components are mounted on the top side of the board. Power supply decoupling capacitors and feedback components are located close to IR3847. The feedback resistors are connected to the output of the remote sense amplifier of the IR3847 and are located close to the IR3847. To improve efficiency, the circuit board is designed to minimize the length of the on-board power ground current path. Separate power ground and analog ground are used and may be connected together using a 0 ohm resistor at one of three possible locations. It is preferred to use one of R43 or R44. Vin Gnd Gnd Vo Top View 2/13/2012 Confidential 3 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice C9 N/S C10 100n 1 Vref R41 N/S R40 N/S Sctrl Sctrl Vref 1 Rt/Sy nc N/S D3 Sy nc Sy nc PGDPU PGDPU PGD PGood Vp 1 1 VCC Vcc- PGDPU OCSelect 1 Confidential PGD Vcc Comp FB RSo U1 D2 N/S 11 Vp 2 Vout 23.2K R9 OCSelect 4 Rt/Sy nc Rt/Sy nc 5 16 PGD 18 8 7 9 Vref R35 1 IR3847 Vin 0 R33 49.9K R18 N/S VCC C25 0.1uF Fb N/S R21 R2 2.67K Vsns C54 N/S C53 N/S 1 Vout_Adj R26 N/S BODE JUMPER 2 R6 20 R11 0 R10 23.2K 0 N/S C38 N/S R20 N/S C24 0.1uF L1 Vo C31 N/S Vout C52 N/S M3 Vsns N/S C4 22uF C3 22uF N/S N/S C45 Fb N/S C29 N/S C28 N/S C27 22uF C20 22uF C19 22uF C18 0 ohm R30 0 ohm 22uF C17 22uF C16 22uF C15 25V 330uF C2 + C1 22uF 330uF PVin R31 C14 0.1uF PVin- PVin+ Vout 1 1 Vo Vo 1 1 Vout- Vout+ N/S C44 N/S C42 N/S C41 N/S C21 N/S C22 + C35 N/S + C36 + C34 N/S N/S + C51 N/S Ground and Signal ( "analog" ) Ground Single point of connection between Power N/S N/S C43 C40 6X22uF/805/6.3V+1X22uF/805/6.3V (transient schematic) N/S 0.1uF C33 C30 R44 0 R27 C5 22uF Optional "1-bit VID" circuit N/S N/S R16 Vo_R_N Vo_R_P 23.2K R15 C6 N/S Ceramic cap 16V 5X22uF 1206 R43 C7 N/S 150nH PCDC1008-R15EMO C32 N/S R32 SWs C56 N/S Fig. 1: Schematic of the IR3847 evaluation board 2.61K R3 C8 R14 N/S R4 84.5 C39 1uF R28 0 2200pF C50 N/S 2 Boot C37 20 0.1uF SW 21 SW SW 22 SW 23 SW 24 SW 25 SW 32 SW 6 Vsns 13 RS+ PGnd 26 C57 22uF C55 N/S 0 R29 N/S R34 Optional Pre-Bias test circuit VPB Agnd N/S 10K 3 R17 C68 C66 4pin jumper 10uF 4 JUMPER 2 2 PGD Vcc+ C11 0 R8 C26 10nF 150pF R1 1K Vp Vp Enable Vref 1 1 VDDQ Vin 1 15 3 Vref 14 17 LGnd 11 1 R19 39.2K PGnd 27 1 1 1 1 2 PGnd 10 PVin PGnd 29 Vp 1 RS12 2/13/2012 1 Enable IRDC3847-P1V2 4 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 Schematic for Transient Load set up Vout VCC 3 1 R22 ExtLoadCtrl R23 2 1 N/S N/S S3 SW N/S R24 Vo_R_P N/S R36 N/S U2 1 2 3 4 R39 N/S C46 N/S C49 N/S VS VS IN OUT2 N/A OUT1 GND GND 8 7 6 5 MIC4452/SO8 N/S R25 M1 IRF6721 N/S Vout N/S R45 C47 N/S N/S R37 N/S C48 N/S 1 C58 N/S C59 N/S C60 N/S C61 N/S C62 22uF C65 N/S C64 N/S C63 N/S I-Monitor R38 N/S Vo_R_N Optional transient load circuit 2/13/2012 Confidential 5 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 Bill of Materials Item Quantity Part Reference Value 1 5 C2 C3 C4 C5 C57 22uF 2 1 C1 C9 C14 C24 C25 6 C37 C33 1 C8 Description Manufacturer Part Number 330uF 22uF,1206,16V, X5R, 20% Panasonic SMD Elecrolytic, Fsize, 25V, 20% Panasonic EEV-FK1E331P 0.1uF 2200pF 0603, 25V, X7R, 10% 2200pF,0603,50V,X7R Panasonic Panasonic ECJ-1VB1E104K ECJ-1VB1H222K 1 C11 150pF 7 C15 C16 C17 C18 22uF C19 C20 C62 50V, 0603, NP0, 5% 0805, 6.3V, X5R, 20% Murata TDK 6 7 8 9 10 11 12 13 14 1 Vo 1 C26 1 L1 1 R1 1 R2 1 R3 1 R4 1 R6 10nF 0.150uH 1K 2.67K 2.61K 84.5 20 Tektronix test connector 0603, 50V, X7R, 10% 0.150uH, DCR=0.29mohm 0603,1/10W,1% 0603,1/10W,1% 0603,1/10W,1% 0603,1/10W,1% 20,0603,1/10 W,1% Tektronix Panasonic Cyntec Rohm Rohm Rohm Panasonic Vishay/Dale C2012X5R0J226M 131-5031-00 ECJ-1VB1H103K PCDC1008-R150EMO MCR03EZPFX1001 MCR03EZPFX2671 MCR03EZPFX2611 ERJ-3EKF84R5V CRCW060320R0FKEA 15 16 17 18 19 20 21 22 23 24 R8 R28 R10 R11 7 R44 R33 R34 1 C39 C66 2 R15 R32 2 R30 R31 1 R18 1 R19 1 R9 1 R17 1 U1 0 1uF 10uF 23.2K 0 49.9K 39.2K 23.2K 10K IR3847 0,0603,1/10 W,5% 0603, X5R, 16V 0603, X5R, 10V 0603,1/10 W,1% 1206,1/4 W,5% 49.9K,0603,1/10 W,1% 39.2K,0603,1/10W,1% 23.2K,0603,1/10W,1% 0603,1/10 W,1% IR3847 5mm X6mm Vishay/Dale TDK TDK Rohm Panasonic Rohm Rohm Rohm Rohm International Rectifier CRCW06030000Z0EA C1608X5R1C105M C1608X5R1A106M MCR03EZPFX2322 ERJ-8GEY0R00V MCR03EZPFX4992 MCR03EZPFX3922 MCR03EZPFX2322 MCR03EZPFX1002 IR3847 3 4 5 2/13/2012 Confidential ECJ3YB1C226M GRM1885C1H151JA01 D 6 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=0A-25A, 1MHz, Room Temperature, no airflow Fig. 2: Start up at 25A Load Ch1:Vin, Ch2:Vo, Ch3:PGood, Ch4:Enable Fig. 4: Start up with 1.08V Pre Bias , 0A Load, Ch2:Vo, Fig. 6: Inductor node at 25A load Ch2:LX 2/13/2012 Fig. 3: Start up at 25A Load, Ch1:Vin, Ch2:Vo, Ch3:VPGood,Ch4:Vcc Fig. 5: Output Voltage Ripple, 25A load Ch1: Vout Fig. 7: Short (Hiccup) Recovery Ch2:Vout; Ch4=Io Confidential 7 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=2.5A-10A, 1MHz, Room Temperature, no air flow Fig. 8: Transient Response, 2.5A to 10A step (2.5A/us) Ch2:Vout 2/13/2012 Confidential 8 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=17.5A-25A, 1MHz, Room Temperature, no air flow Fig. 9: Transient Response, 17.5A to 25A step (2.5A/us) Ch2:Vout 2/13/2012 Confidential 9 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=0A-25A, 1MHz, Room Temperature, No air flow Fig. 10: Bode Plot at 25A load shows a bandwidth of 170kHz and phase margin of 51degrees 2/13/2012 Confidential 10 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=0A-25A, Room Temperature, no air flow Fig.11: Efficiency versus load current Fig.12: Power loss versus load current 2/13/2012 Confidential 11 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice IRDC3847-P1V2 THERMAL IMAGES Vin=12.0V, Vo=1.2V, Io=0A-25A, 1MHz, Room Temperature, No airflow Fig. 13: Thermal Image of the board at 25A load Test point 1 is IR3847: 1030C Test point 2 is inductor: 700C 2/13/2012 Confidential 12 This evaluation board is a preliminary version meant for the engineering evaluation of the IR3847. Based on the results of the continuing evaluation, this board can evolve and change without notice