IRDC3894-P1V2 SupIRBuck TM USER GUIDE FOR IR3894 EVALUATION BOARD 1.2Vout DESCRIPTION The IR3894 is a synchronous buck converter, providing a compact, high performance and flexible solution in a small 5mm X 6 mm Power QFN package. Key features offered by the IR3894 include internal Digital Soft Start/Soft Stop, precision 0.5Vreference 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, smart internal LDO and pre-bias start-up. 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 and the current limit is thermally compensated. This user guide contains the schematic and bill of materials for the IR3894 evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for IR3894 is available in the IR3894 data sheet. BOARD FEATURES • Vin = +12V (+ 13.2V Max) • Vout = +1.2V @ 0- 12A • Fs=400kHz • L= 0.8uH • Cin= 5x22uF (ceramic 1206) + 1X330uF (electrolytic) • Cout=6x47uF (ceramic 0805) 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 1 IRDC3894-P1V2 CONNECTIONS AND OPERATING INSTRUCTIONS A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum of 12A load should be connected to VOUT+ and VOUT-. The input and output connections of the board are listed in Table I. IR3894 has only one input supply and internal LDO generates Vcc from Vin. If operation with external Vcc is required, then R15 can be removed and external Vcc can be applied between Vcc+ and Vcc- pins. Vin pin and Vcc/LDOout pins should be shorted together for external Vcc operation (use zero ohm resistor for R29). The output can track voltage at the Vp pin. For this purpose, Vref pin is to be connected to ground (use zero ohm resistor for R21). The value of R14 and R28 can be selected to provide the desired tracking ratio between output voltage and the tracking input. Table I. Connections Connection Signal Name VIN+ Vin (+12V) VIN- Ground of Vin Vout+ Vout(+1.2V) Vout- Ground for Vout Vcc+ Vcc/ LDO_out Pin Vcc- Ground for Vcc input Enable Enable PGood Power Good Signal Gnd Analog ground LAYOUT The PCB is a 4-layer board (2.23”x2”) using FR4 material. All layers use 2 Oz. copper. The PCB thickness is 0.062”. The IR3894 and other major power components are mounted on the top side of the board. Power supply decoupling capacitors, the bootstrap capacitor and feedback components are located close to IR3894. The feedback resistors are connected to the output at the point of regulation and are located close to the SupIRBuck IC. To improve efficiency, the circuit board is designed to minimize the length of the on-board power ground current path. 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 2 IRDC3894-P1V2 Vin Gnd Gnd Vout Enable Top View VDDQ Vref Sync PGood AGnd S_Ctrl Vsns Vcc+ Vcc- Bottom View Fig. 1: Connection Diagram of IR3894/94 Evaluation Boards 9/20/2012 3 IRDC3894-P1V2 Fig. 2: Board Layout-Top Layer Single point connection between Analog Gnd and PGnd Fig. 3: Board Layout-Bottom Layer 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 4 IRDC3894-P1V2 Fig. 4: Board Layout-Mid Layer 1 Fig. 5: Board Layout-Mid Layer 2 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 5 PGood VCC N/A C10 R17 49.9K Vcc+ Vcc- N/S R28 R14 0 VDDQ Agnd 1 4.87k R1 C26 C12 1nF SY NC 4.7nF 60.4K R9 120pF C11 S_Ctrl 5 4 3 1 2.2uF C23 VCC S_Ctrl Vp Rt_Sy nc AGnd COMP 1 15 C32 1.0uF 49.9K IR3894 R7 0 (N/S) U1 SW VCC R2 2200pF C8 PGND 5.62k 11 12 C7 0.1uF 13 R3 4.02k 158 R4 PGnd SW PVin N/S R29 R10 0 R15 0 A Vsns n/a 20 R6 C25 0.1uF C24 L1 B R11 5.62k 4.02k R12 0.8uH R50 0 C34 C33 n/s n/s C30 n/a C6 C28 n/a + C36 N/S + C35 N/S 22uF C29 n/a Fig. 6: Schematic of the IR3894 evaluation board 0 n/a C37 FB R13 6 16 7.5k R19 2 VREF 1 1 Boot 1 1 9 PGood 7 1 14 Vsns 8 R21 N/S 1 GND 17 Enable Vcc/LDO_OUT 10 Vin 1 R18 1 VREF 1 1 1 9/20/2012 1 Enable C27 n/a C20 47uF C5 22uF C19 47uF C4 22uF C3 C18 47uF C16 47uF C2 22uF C17 47uF 22uF C1 + C15 47uF 1 1 1 1 1 1 1 1 C14 0.1uF Vout 330uF/25V Vin Vout- Vout- Vout+ Vout+ Vin- Vin- Vin+ Vin+ IRDC3894-P1V2 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 6 IRDC3894-P1V2 Bill of Materials Item Qty Part Reference Value Description Manufacturer Part Number 1 1 C1 330uF SMD Electrolytic F size 25V 20% Panasonic EEV-FK1E331P 2 5 C2 C3 C4 C5 C6 22uF 1206, 16V, X5R, 20% TDK C3216X5R1C226M 3 3 C7 C14 C24 0.1uF 0603, 25V, X7R, 10% Murata GRM188R71E104KA01B 4 1 C12 1nF 0603, 50V, 5% Murata GRM1885C1H102JA01D 5 1 C8 2200pF 0603,50V,X7R Murata GRM188R71H222KA01B 6 1 C11 120pF 0603, 50V, NP0, 5% Murata GRM1885C1H121JA01D 7 6 C15 C16 C17 C18 C19 C20 47uF TDK C2012X5R0J476M 8 1 C23 2.2uF 0603, 16V, X5R, 20% TDK C1608X5R1C225M 9 1 C26 4.7nF 0603, 25V, X7R, 10% Murata GRM188R71E472KA01J 10 1 C32 1.0uF 0603, 25V, X5R, 10% Murata GRM188R61E105KA12D 11 1 L1 0.8uH SMD 7.2x7.5x7mm, 2.08mΩ Coilcraft XAL7070-801ME 12 1 R1 4.87K Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF4871V 13 2 R2 R11 5.62K Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF5621V 14 2 R3 R12 4.02K Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF4021V 15 1 R4 158 Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF1580V 16 1 R6 20 Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF20R0V 17 1 R9 60.4K Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF6042V 18 5 R10 R13 R14 R15 R50 0 Panasonic ERJ-3GEY0R00V 19 2 R17 R18 49.9K Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF4992V 20 1 R19 7.5K Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF7501V 21 1 U1 IR3894 PQFN 5x6mm IR IR3894MPBF 9/20/2012 0805, 6.3V, X5R, 20% Thick Film, 0603,1/10W Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 7 IRDC3894-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=0-12A, Room Temperature, no airflow Fig. 8: Start up at 12A Load Ch1:Vin, Ch2:Vout, Ch3:PGood,Ch4:Vcc Fig. 7: Start up at 12A Load Ch1:Vin, Ch2:Vout, Ch3: PGood,Ch4:Enable Fig. 10: Output Voltage Ripple, 12A load Ch2: Vout , Fig. 9: Start up with 1V Pre Bias , 0A Load, Ch2:Vo Fig. 12: Short circuit (Hiccup) Recovery Ch2:Vout , Ch4:Iout (5A/1V) Fig. 11: : Inductor node at 12A load Ch1:LX 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 8 IRDC3894-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=0-12A, Room Temperature, no air flow Fig. 13: Transient Response, 4A to 7A step Ch2:Vout Ch4-Iout 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 9 IRDC3894-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=0-12A, Room Temperature Fig. 14: Bode Plot at 12A load bandwidth = 81.97kHz, phase margin = 52.29º, Gain Margin = 10.77dB 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 10 IRDC3894-P1V2 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vo=1.2V, Io=0-12A, Room Temperature, no air flow 90 88 Efficiency [%] 86 84 82 80 78 76 74 72 1 2 3 4 5 6 7 Io [A] 8 9 10 11 12 Power Loss [W] Fig.15: Efficiency versus load current 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 1 2 3 4 5 6 7 Io [A] 8 9 10 11 12 Fig.16: Power loss versus load current 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 11 IRDC3894-P1V2 THERMAL IMAGES Vin=12.0V, Vo=1.2V, Io=0-12A, Room Temperature, No Air flow Fig. 17: Thermal Image of the board at 12A load Test point 1 is IR3894 Test point 2 is inductor 9/20/2012 12 IRDC3894-P1V2 PACKAGE INFORMATION DIM A A1 b b1 c D E e e1 e2 MILIMITERS MIN MAX 0.800 1.000 0.000 0.050 0.375 0.475 0.250 0.350 0.203 REF. 5.000 BASIC 6.000 BASIC 1.033 BASIC 0.650 BASIC 0.852 BASIC INCHES MIN MAX 0.0315 0.0394 0.0000 0.0020 0.1477 0.1871 0.0098 0.1379 0.008 REF. 1.969 BASIC 2.362 BASIC 0.0407 BASIC 0.0256 BASIC 0.0335 BASIC DIM L M N O P Q R S t1, t2, t3 t4 t5 MILIMITERS MIN MAX 0.350 0.450 2.441 2.541 0.703 0.803 2.079 2.179 3.242 3.342 1.265 1.365 2.644 2.744 1.500 1.600 0.401 BASIC 1.153 BASIC 0.727 BASIC INCHES MIN MAX 0.0138 0.0177 0.0961 0.1000 0.0277 0.0316 0.0819 0.0858 0.1276 0.1316 0.0498 0.0537 0.1041 0.1080 0.0591 0.0630 0.016 BACIS 0.045 BASIC 0.0286 BASIC Figure 20: Package Dimensions IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 This product has been designed and qualified for the Industrial market Visit us at www.irf.com for sales contact information Data and specifications subject to change without notice. 11/11 9/20/2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3894. Based on the results of the continuing evaluation, this board can evolve and change without notice 13