IRDC3895-P3V3 SupIRBuck TM USER GUIDE FOR IR3895 EVALUATION BOARD 3.3Vout DESCRIPTION The IR3895 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 IR3895 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 IR3895 evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for IR3895 is available in the IR3895 data sheet. BOARD FEATURES • Vin = +12V (+ 13.2V Max) • Vout = +3.3V @ 0- 16A • Fs= 400kHz • L= 1.0uH • Cin= 5x10uF (ceramic 0805) + 1X0.1uF (ceramic 0402) + 1X330uF (electrolytic, 25V) • Cout= 6x47uF (ceramic 0805) + 1X0.1uF (ceramic 0402) 9/25/2012 1 IRDC3895-P3V3 CONNECTIONS AND OPERATING INSTRUCTIONS A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum of 16A load should be connected to VOUT+ and VOUT-. The input and output connections of the board are listed in Table I. IR3895 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(+3.3V) 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 IR3895 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 IR3895. 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. 9/25/2012 2 IRDC3895-P3V3 Vin Gnd Gnd Vout Enable Top View VDDQ Vref Sync PGood AGnd S_Ctrl Vsns Vcc+ Vcc- Bottom View Fig. 1: Connection Diagram of IR3895/94 Evaluation Boards 9/25/2012 3 IRDC3895-P3V3 Fig. 2: Board Layout-Top Layer Single point connection between Analog Gnd and PGnd Fig. 3: Board Layout-Bottom Layer 9/25/2012 4 IRDC3895-P3V3 Fig. 4: Board Layout-Mid Layer 1 Fig. 5: Board Layout-Mid Layer 2 9/25/2012 5 PGood VCC N/A C10 R17 49.9K Vcc+ Vcc- N/S R28 R14 0 1 1 1 1 VDDQ 2k R1 10nF C26 SYNC 60.4k R9 220pF C12 1nF S_Ctrl 5 4 3 1 0 n/a C37 Enable 1 C32 1.0uF 49.9K R18 IR3895 R7 0 (N/S) R3 715 100 R4 PGnd SW PVin U1 N/S R29 SW VCC R2 3300pF C8 PGND 4.02k 11 12 C7 0.1uF 13 R10 0 R15 0 A 0.1uF C24 Vsns C25 n/a R6 20 C6 B R11 4.02k R12 715 L1 1.0uH R50 0 C4 10uF C3 C27 C20 n/a 47uF C19 47uF C18 47uF + C36 N/S + C35 N/S 47uF, 0805, 6.3V, X5R, 20% C28 n/a C16 47uF C2 10uF C17 47uF 10uF C1 + 1 1 1 1 1 1 1 1 C15 C14 47uF 0.1uF Vout 330uF/25V IR3895 5mmx6mm Power QFN package, Max Io=16A C34 C33 C30 n/a n/a n/a C29 n/a C5 10uF Input ceramic: 1206 10uF Cyntec Inductor( PIMC104T-1R0MN) C9 n/a Fig. 6: Schematic of the IR3895 evaluation board 2.2uF C23 VCC S_Ctrl Vp Rt_Sy nc AGnd COMP FB R13 6 16 7.5k R19 2 1 Agnd Agnd Agnd Agnd Agnd Agnd 1 Agnd 1 1 C11 1 7 VR EF 9 PG ood R21 N/S 1 V s ns 8 15 E n a b le V c c /LD O _O U T 10 V in 14 Boot GND 17 1 1 1 VREF 1 1 1 1 1 9/25/2012 1 Vin Vout- Vout- Vout+ Vout+ Vin- Vin- Vin+ Vin+ IRDC3895-P3V3 6 IRDC3895-P3V3 Bill of Materials Item Qty 330uF Description SMD Electrolytic F size 25V 20% Manufactur er Panasonic EEV-FK1E331P Part Reference Value Part Number 1 1 C1 2 5 C2 C3 C4 C5 C6 10uF 1206, 25V, X5R, 20% TDK C3216X5R1E106M 3 3 C7 C14 C24 0.1uF TDK C1608X7R1E104K 4 1 C12 1nF 603, 25V, X7R, 10% 0603, 25V, COG, 5% Murata GRM1885C1E102JA01D 5 1 C8 3300pF 6 1 C11 220pF 0603,50V,X7R,10% 0603, 50V, COG, 5% Murata Murata GRM188R71H332KA01D GRM1885C1H221JA01D 7 6 C15 C16 C17 C18 C19 C20 47uF 0805, 6.3V, X5R, 20% Murata GRM21BR60J476ME15 8 1 C23 2.2uF 0603, 16V, X5R, 20% TDK C1608X5R1C225M Murata GRM188R71E103KA01J Murata GRM188R61E105KA12D 9 1 C26 10nF 0603, 25V, X7R, 10% 10 1 C32 1.0uF 0603, 25V, X5R, 10% 11 1 L1 1.0uH 12 1 R1 2k 13 2 R2 R11 4.02k SMD 10.3x11.5x4.0mm,3.0mΩ, Isat. 36A Cyntec Thick Film, 0603,1/10W,1% Panasonic Thick Film, 0603,1/10W,1% Panasonic PIMC104T-1R0MN ERJ-3EKF2001V ERJ-3EKF4021V 14 2 R3 R12 715 Thick Film, 0603,1/10W,1% 15 1 R4 100 Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF1000V 16 1 R6 20 Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF20R0V Yageo 311-715HRCT-ND 17 1 R9 60.4k Thick Film, 0603,1/10W,1% Yageo 311-60.4KHCT-ND 18 5 R10 R13 R14 R15 R50 0 Thick Film, 0603,1/10W Panasonic ERJ-3GEY0R00V 19 2 R17 R18 49.9k Thick Film, 0603,1/10W,1% Panasonic ERJ-3EKF4992V Panasonic ERJ-3EKF7501V IR IR3895MTR1PBF 20 1 R19 7.5k Thick Film, 0603,1/10W,1% 21 1 U1 IR3895 PQFN 5x6mm 9/25/2012 7 IRDC3895-P3V3 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vout=3.3V, Iout=0-16A, Room Temperature Fig. 7: Bode Plot at 16A load shows a bandwidth of 72.36kHz and phase margin of 65.29º. 9/25/2012 8 IRDC3895-P3V3 TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vout=3.3V, Iout=0-16A, Room Temperature, no air flow Fig.8: Efficiency versus load current Fig.9: Power loss versus load current 9/25/2012 9 IRDC3895-P3V3 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 10: 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. 12/11 9/25/2012 10