IRDC3891 SupIRBuck TM USER GUIDE FOR IR3891 EVALUATION BOARD DESCRIPTION The IR3891 is a dual synchronous buck converter, providing a compact, high performance and flexible solution in a small 5mm X 6mm Power QFN package. Key features offered by the IR3891 include internal Digital Soft Start, precision 0.5V 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, pre-bias start-up, output over voltage protection as well as open feedback line protection. 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 IR3891 evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for IR3891 is available in the IR3891 data sheet. BOARD FEATURES • Vin = +5.0V • Fs = 700kHz • Vout1 = +2.5V @ 4A Vout2 = +1.8V @ 4A • L1 = 2.2uH L2 = 2.2uH • Cout1=4x22uF (ceramic 0805) Cout2=4x22uF (ceramic 0805) • Cin= 4x10uF (ceramic 1206) + 1x330uF (electrolytic) 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 1 IRDC3891 CONNECTIONS and OPERATING INSTRUCTIONS A well regulated +5.0V input supply should be connected to VIN+ and VIN-. A maximum 4A load should be connected to VOUT+ and VOUT-. The connection diagram is shown in Fig. 1 and inputs and outputs of the board are listed in Table I. IR3891 has only one input supply and internal LDO generates Vcc from Vin. If operation with external Vcc is required, then R3 should be removed and external Vcc should be applied between Vcc+ and Vcc- pins. Vin pin (input of the LDO) and Vcc/LDO pins should be shorted together (populate R4) for external Vcc operation. The output of channel2 (Vout2) can follow the voltage at the Seq pin. For this purpose, The value of R5 and R6 can be selected to provide the desired sequencing ratio between Seq input and Vout2. For normal operation (non-sequencing) Seq pin should be left floating. Seq pin is internally pulled up to 3.3V. Table I. Connections Connection Signal Name VIN+ PVin (+5V) VIN- Ground of PVin VOUT1+ Vout1 (+2.5V) VOUT1- Ground of Vout1 VOUT2+ Vout2 (+1.8V) VOUT2- Ground of Vout2 VCC+ VCC/LDO pin VCC- Connected to PGND VSEQ Sequence input EN1, EN2 Enable input of each channel Sync Synchronous input LAYOUT The PCB is a 4-layer board. All of layers are 2 Oz. copper. The IR3891 and other components are mounted on the top and bottom side of the board. Power supply decoupling capacitors, the Bootstrap capacitor and feedback components are located close to IR3891. The feedback resistors are connected to the output voltage at the point of regulation and are located close to IR3891. To improve efficiency, the circuit board is designed to minimize the length of the on-board power ground current path. 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 2 IRDC3891 Connection Diagram V OUT1 V OUT2 GROUND GROUND PGood1 SEQ PGood2 Sync Vsns1 EN1 Vsns2 EN2 VPG Vcc/LDO_out Vin GROUND Fig. 1: Connection diagram of IR3891 evaluation board (top and bottom) 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 3 IRDC3891 R50 is the Single point connection between AGND and PGND. Fig. 2: Board layout, top layer Fig. 3: Board layout, bottom layer 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 4 IRDC3891 Fig. 4: Board layout, mid-layer I Fig. 5: Board layout, mid-layer II 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 5 1 1 J111 JUMPER1 J211 Vin Vcc- 21k R19 N/S N/S 21k R29 41.2K R28 EN1 C113 C213 R211 N/S N/S R111 41.2K 330uF/25V R18 JUMPER1 Vin- Vin- 1 + C1 Vcc+ EN2 N/S C29 VCC N/S C19 C212 10uF VSeq N/S C7 C211 10uF C112 R5 0 N/S R6 2.2uF C8 10uF N/S C9 C6 1.0uF C111 10uF 0 R4 0 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 34K R9 Seq GND1 Vcc/LDO Vin EN1 Vsns1 R11 4.87k C11 5.6nF IR3891 Vsns2 17 0.1uF C20 Vpg 0 Vin Vpg R20 PGood2 NS C27 C22 100pF R26 R27 2.61K 6.81k NS R22 R15 20 B1 C122 22uF C123 22uF C124 22uF C125 22uF C126 N/S C127 C128 N/S N/S A2 20 R25 B2 C222 22uF C223 22uF C224 22uF C225 22uF 0 R50 C226 N/S C129 V1 N/S Agnd Agnd 1 1 1 Vout1+ Vout2- Vout2- Vout2- Vout2+ Vout2+ Vout2+ Vout1- Vout1- Vout1- Vout1+ Vout1+ Agnd Agnd Agnd Agnd Agnd 1 1 1 C221 0.1uF Vout2 1 1 1 C121 0.1uF 1 1 Vout1 1 C228C229 N/S N/S V2 PGNDPGND PGND Agnd C227 N/S Output ceramic: 0805 (use 1206 footprint) C23 A1 2200pF 6.81k R23 2.61K 10 R24 2.2uH L2 R21 R2 49.9K VCC SW22 2.2uH L1 7.15K C26 R8 N/S SW2 R12 6.19k C21 C24 0.1uF 13 14 15 16 0.1uF SW11 C13 2200pF 5.6nF Boot2 PVin2 PGnd2 SW2 SW1 PGnd1 18 C14 0.1uF C10 0 R10 SW1 R13 1.54k 69.8 R14 Fig.6: Schematic of the IR3891 evaluation board DIODE D1 6 5 4 3 2 1 U1 6.19k C12 100pF R17 1.54k R7 N/S Vpg R1 49.9K VCC PGood1 SY NC R3 1 Input ceramic: 1206 1 NS GND2 Vin- 1 2 1 2 22 Comp1 1 1 PVin1 Vin+ 1 Boot1 C17 7 FB1 9 1 Vin+ 1 FB2 10 24 Rt/Sync 21 PGood1 11 23 EN2 8 20 Comp2 19 PGood2 12 1 1 1 1 1 1 1 1 1 1 1 1 1 1 R16 1 Vin 1 1 1 1 Vsns2 1 1 1 NS 1 C16 1 Vsns1 1 10-01-2012 1 Vin+ IRDC3891 6 IRDC3891 Bill of Materials Vin=5.0V, Vout1=2.5V/4A, Vout2=1.8V/4A, fs=700KHz Item 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Qty Part Reference 1 C1 4 C111 C112 C211 C212 1 C6 1 C8 6 C10 C14 C20 C24 C121 C221 1 C11 1 C12 2 C13 C23 1 C21 1 C22 C122 C123 C124 C125 8 C222 C223 C224 C225 1 L1 1 L2 2 R1 R2 6 R3 R4 R5 R10 R20 R50 1 R9 1 R11 2 R12 R16 2 R13 R17 1 R14 2 R15 R25 2 R18 R28 2 R19 R29 1 R21 2 R22 R26 2 R23 R27 1 R24 2 R111 R211 2 J111 J211 1 R6 C7 C9 C16 C17 C19 C26 C27 16 C29 C113 C126 C127 C128 C213 C226 C227 C228 1 D1 1 U1 10-01-2012 Value 330uF 10uF 1.0uF 2.2uF 0.1uF 5.6nF 100pF 2200pF 5.6nF 100pF 22uF 2.2uH 2.2uH 49.9K 0 34K 4.87K 6.19K 1.54K 69.8 20 41.2K 21K 7.15K 6.81K 2.61K 10 N/S jumper N/S Description Manufacturer Part Number SMD Electrolytic F size 25V 20% 1206, 25V, X5R, 10% 0603, 25V, X5R, 10% 0603, 16V, X5R, 20% 0603, 25V, X7R, 10% 0603, 50V, X7R, 10% 0603, 50V, NP0, 5% 0603, 50V, X7R, 10% 0603, 50V, X7R, 10% 0603, 50V, NP0, 5% Panasonic TDK Murata TDK Murata Murata Murata Murata Murata Murata EEV-FK1E331P C3216X5R1E106K GRM188R61E105KA12D C1608X5R1C225M GRM188R71E104KA01B GRM188R71H562KA01D GRM1885C1H101JA01D GRM188R71H222KA01D GRM188R71H562KA01D GRM1885C1H101JA01D 0805, 6.3V, X5R, 20% TDK C2012X5R0J226M SMD 8.4x7.9x7.2mm,DCR=4.4mΩ SMD 8.4x7.9x7.2mm,DCR=4.4mΩ Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Wurth Elektronik Wurth Elektronik Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic 7443340220 7443340220 ERJ-3EKF4992V ERJ-3GEY0R00V ERJ-3EKF3402V ERJ-3EKF4871V ERJ-3EKF6191V ERJ-3EKF1541V ERJ-3EKF69R8V ERJ-3EKF20R0V ERJ-3EKF4122V ERJ-3EKF2102V ERJ-3EKF7151V ERJ-3EKF6811V ERJ-3EKF2611V ERJ-3EKFR10R0V Vishay IR BAS40-02VGS08 IR3891MPBF This is a simple jumper N/S IR3891 Schottky, 40V, SOD-523 PQFN 5x6mm Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 7 IRDC3891 TYPICAL OPERATING WAVEFORMS PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=0-4A, Room Temperature, No Air Flow Fig. 7: Start up at 4A Load (Note 1) Ch1:Vout1, Ch2:Vout2, Ch3:Vcc/LDO, Ch4:Vin Fig. 8: Start up at 4A Load (Note 1) Ch1:Vout1, Ch2:Vout2, Ch3:PGood1, Ch4: PGood2 Fig. 9: Start up with 1.99V Prebias, 0A Load, Ch1:Vout1, Ch3:PGood1 Fig. 11: Inductor nodes at 4A load Ch1:SW1, Ch2:SW2 10-01-2012 Fig. 10: Start up with 1.58V Prebias, 0A Load, Ch2:Vout2, Ch4:PGood2 Fig. 12: Output Voltage Ripple, 4A load on each channel (Note2) Ch1: Vout1, Ch2: Vout2 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 8 IRDC3891 TYPICAL OPERATING WAVEFORMS PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=0-4A, Room Temperature, No Air Flow Fig. 14: Short circuit (Hiccup) Response Ch1:Vout2, Ch4:Iout2 Fig. 13: Short circuit (Hiccup) Response Ch1:Vout1, Ch4:Iout1 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 9 IRDC3891 TYPICAL OPERATING WAVEFORMS PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Room Temperature, No Air Flow Fig. 15: Transient Response of channel1 0A-1.6A (0-40%), Ch1:Vout1 , Ch2:Vout2, Ch4: Iout1 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 10 IRDC3891 TYPICAL OPERATING WAVEFORMS PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Room Temperature, No Air Flow Fig. 16: Transient Response of channel2 0A-1.6A (0-40%), Ch1:Vout1 , Ch2:Vout2, Ch4: Iout2 Note1: Enable is tied to Vin via a resistor divider. Note2: Vo ripple signal is taken across C125 and C225 capacitors. 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 11 IRDC3891 Bode Plot, Channel1 PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=4A, Room Temperature, No Air Flow Fig.17: Bode Plot of CH1 at 4A load: bandwidth = 97.1 kHz, phase margin = 64.2 degrees, gain margin = 15.4dB 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 12 IRDC3891 Bode Plot, Channel2 PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=4A, Room Temperature, No Air Flow Fig.18: Bode Plot of CH2 at 4A load: bandwidth = 105.1 kHz, phase margin = 59.8 degrees, gain margin = 14.45dB 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 13 IRDC3891 Efficiency and Power Loss of channel1 PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2 is disabled (EN2=low), Io1= 0-4A, Room Temperature, No Air Flow 97 95 Efficiency [%] 93 91 89 87 85 83 81 79 77 0.00 0.50 1.00 1.50 2.00 Io [A] 2.50 3.00 3.50 4.00 0.5 1.0 1.5 2.0 Io [A] 2.5 3.0 3.5 4.0 0.8 Power Loss [W] 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.0 Fig.19: Efficiency and power loss vs. load current for channel1 (Vout1 = 2.5V) 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 14 IRDC3891 Efficiency and Power Loss of channel2 PVin=Vin=Vcc=5.0V, Vout1 is disabled (EN1=low), Vout2=1.8V, Io2=0-4A, Room Temperature, No Air Flow 97 95 Efficiency [%] 93 91 89 87 85 83 81 79 77 0.00 0.50 1.00 1.50 2.00 Io [A] 2.50 3.00 3.50 4.00 0.5 1.0 1.5 2.0 Io [A] 2.5 3.0 3.5 4.0 0.8 Power Loss [W] 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.0 Fig.20: Efficiency and power loss vs. load current for channel2 (Vout2 = 1.8V) 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 15 IRDC3891 Thermal Image PVin=Vin=Vcc=5.0V, Vout1=2.5V, Vout2=1.8V, Io1= Io2=4A, Room Temperature, No Air Flow Fig.21: Thermal Image at Io1=Io2=4A load Test Point 1: IR3891, Test Point 2: Inductor_Ch1, Test Point 3: Inductor_Ch2 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice. 16 IRDC3891 IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 Visit us at www.irf.com for sales contact information Data and specifications subject to change without notice. 10/11 10-01-2012 Confidential This evaluation board is a preliminary version meant for the engineering evaluation of the IR3891. Based on the results of the continuing evaluation, this board can evolve and change without notice.