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 = +12.0V • Fs = 600kHz • Vout1 = +3.3V @ 0.9A Vout2 = +1.8V @ 0.3A • L1 = 10uH L2 = 15uH • Cout1=1x22uF (ceramic 0805) Cout2=1x22uF (ceramic 0805) • Cin= 2x10uF (ceramic 1206) + 1x330uF (electrolytic, optional) 01-23-2013 WD 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 input supply should be connected to VIN+ and VIN-. A designed maximum 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 (+12V) VIN- Ground of PVin VOUT1+ Vout1 (+3.3V) 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. 01-23-2013 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) 01-23-2013 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 01-23-2013 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 01-23-2013 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 1 + C1 J111 JUMPER1 J211 N/S N/S N/S Vin EN1 C212 C113 N/S 11.8k R28 11.8k R29 84.5K VCC Vcc+ Vcc- C19 R19 VSeq EN2 N/S C29 DIODE SY NC D1 0 R5 2.2uF C8 N/S C112 R6 N/S N/S C7 10uF C211 Input ceramic: 1206 C213 R211 N/S N/S R111 84.5K 330uF/25V R18 JUMPER1 Vin- Vin- Vin- 1 2 1 2 1 1 1 39.2K R9 N/S C9 C6 1.0uF 10uF C111 N/S R4 0 R3 C12 Vsns2 9 8 7 6 5 4 3 2 1 R11 5.76k Vsns2 EN2 Rt/Sy nc Seq GND Vcc/LDO Vin EN1 Vsns1 U1 82pF 10nF C11 Vpg R1 R7 49.9K N/S VCC PGood1 1 29 1 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. 25 IR3891 10K 3.3nF C22 47pF R21 C21 0.1uF C24 NS C27 Vin 0 R10 C14 0.1uF 0 R20 19 20 21 22 R27 2.74K Vpg 0.1uF C20 R26 7.15k C26 NS SW2 SW2 SW1 SW1 0.1uF C10 SW22 PGood2 R2 49.9K VCC R8 N/S Vpg SW2 R23 2.74K 130 R24 10uH L1 20 R15 B1 C123 N/S C122 22uF N/S C124 N/S C125 N/S C126 N/S C127 N/S 2200pF C23 15uH L2 A2 20 R25 B2 C223 N/S C222 22uF N/S C224 N/S C225 0 R50 N/S C226 N/S C229 1 1 1 1 1 1 C221 0.1uF 1 1 Vout2 1 1 1 1 C121 0.1uF Vout1 Vout2- Vout2- Vout2- Vout2+ Vout2+ Vout2+ Vout1- Vout1- Vout1- Vout1+ Vout1+ Vout1+ Agnd Agnd Agnd Agnd Agnd V2 V1 Agnd Agnd N/S PGND PGND PGND Agnd N/S C227 N/S C129 C228 C128 Output ceramic: 0805 (use 1206 footprint) R22 A1 7.15k SW11 SW1 R13 1.02k 5.76k R12 C13 2200pF 130 1 R14 1 Fig.6: Schematic of the IR3891 evaluation board 10 1 1 1 31 FB1 FB2 24 Vin+ 11 PGood1 30 Comp1 Comp2 28 Boot2 13 PGood2 12 Boot1 27 PVin1 PVin2 14 23 PGND1 26 PVin1 PVin2 15 PGND1 PGND2 16 PGND1 PGND2 17 PGND2 18 1 1 1 Vin+ 1 1 1 5.76k 1 R17 1.02k 1 1 NS 1 C17 1 Vin 1 1 1 1 R16 1 1 1 1 1 Vin+ 1 C16 NS 1 01-23-2013 1 Vsns1 IRDC3891 6 IRDC3891 Bill of Materials Vin=12.0V, Vout1=3.3V/0.9A, Vout2=1.8V/0.3A, fs=600KHz 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 Qty Part Reference Value 1 2 1 1 6 1 1 2 1 1 2 1 1 2 5 1 1 2 2 1 2 2 2 1 2 2 1 2 2 2 1 1 C1 C111 C211 C6 C8 C10 C14 C20 C24 C121 C221 C11 C12 C13 C23 C21 C22 C122 C222 L1 L2 R1 R2 R3 R5 R10 R20 R50 R9 R11 R12 R16 R13 R17 R14 R15 R25 R18 R28 R19 R29 R21 R22 R26 R23 R27 R24 R111 R211 J111 J211 R4 R6 D1 U1 330uF 10uF 1.0uF 2.2uF 0.1uF 10nF 82pF 2200pF 3.3nF 47pF 22uF 10uH 15uH 49.9K 0 39.2K 5.76K 5.76K 1.02K 130 20 84.5K 11.8K 10K 7.15K 2.74K 130 N/S jumper N/S 01-23-2013 IR3891 Description 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% 0805, 6.3V, X5R, 20% SMD 6.3 x 6.5 x 6.1mm,27.00mΩ SMD 6.3 x 6.5 x 6.1mm,39.77mΩ 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% Manufacturer Part Number Panasonic TDK Murata TDK Murata Murata Murata Murata Murata Murata TDK Coilcraft Coilcraft Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic EEV-FK1E331P C3216X5R1E106K GRM188R61E105KA12D C1608X5R1C225M GRM188R71E104KA01B GRM188R71H103KA01B GRM1885C1H820JA01D GRM188R71H222KA01B GRM188R71H332KA01B GRM1885C1H470JA01D C2012X5R0J226M XAL6060-103ME XAL6060-153ME ERJ-3EKF4992V ERJ-3GEY0R00V ERJ-3EKF3922V ERJ-3EKF5761V ERJ-3EKF5761V ERJ-3EKF1021V ERJ-3EKF1300V ERJ-3EKF20R0V ERJ-3EKF8452V ERJ-3EKF1182V ERJ-3EKF1002V ERJ-3EKF7151V ERJ-3EKF2741V ERJ-3EKF1300V Vishay IR BAS40-02VGS08 IR3891MPBF This is a simple jumper 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 Vin=12.0V, Vcc/LDO=5.3V, Vout1=3.3V, Io1=0.9A, Vout2=1.8V, Io2=0.3A, Room Temperature, No Air Flow Fig. 7: Start up at full Loads Ch1:Vout1, Ch2:Vout2, Ch3:Vcc/LDO, Ch4:Vin Fig. 8: Start up at full Loads Ch1:Vout1, Ch2:Vout2, Ch3:PGood1, Ch4: PGood2 Fig. 9: Start up with 2.5V Prebias, 0A Load, Ch1:Vout1, Ch3:PGood1 Fig. 10: Start up with 1.5V Prebias, 0A Load, Ch2:Vout2, Ch4:PGood2 Fig. 11: Inductor node at 0.9A load Ch1:SW1 Fig. 12: Inductor node at 0.3A load Ch1:SW2 01-23-2013 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 Vin=12.0V, Vcc/LDO=5.3V, Vout1=3.3V, Io1=0.9A Vout2=1.8V, Io2=0.3A, Room Temperature, No Air Flow Fig. 13: Short circuit (Hiccup) Response Ch1:Vout1, Ch2:Vout2 , Ch3:PGood1 Fig. 14: Short circuit (Hiccup) Response Ch1:Vout1, Ch2:Vout2 , Ch3:PGood2 Fig. 15: Output Voltage Ripple, full load on each channel, Ch1: Vout1, Ch2: Vout2 01-23-2013 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 Vin=12.0V, Vcc/LDO=5.3V, Vout1=3.3V, Vout2=1.8V, Room Temperature, No Air Flow Fig. 16: Transient Response of channel1 0.2A-0.7A , Ch1:Vout1 , Ch2:Vout2, Ch4: Io1 01-23-2013 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 Vin=12.0V, Vcc/LDO=5.3V, Vout1=3.3V, Vout2=1.8V, Room Temperature, No Air Flow Fig. 17: Transient Response of channel2 0A-0.3A, Ch1:Vout1 , Ch2:Vout2, Ch4: Io2 Note1: Enable is tied to Vin via a resistor divider. Note2: Vo ripple signal is taken across C122 and C222 capacitors. 01-23-2013 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 Vin=12.0V, Vcc/LDO=5.3V, Vout1=3.3V, Io1= 0.9A, Vout2=1.8V, Io2=0.3A, Room Temperature, No Air Flow 200 40 150 100 50 0 0 -50 -20 TR2/° TR1/dB 20 -100 -150 -40 103 104 105 -200 f/Hz TR1: Mag(Gain) TR2: Unwrapped Phase(Gain) Fig.18: Bode Plot of CH1 at 0.9A load Bandwidth= 110.27Khz, Phase Margin= 53 degrees, Gain Margin =10.91dB 01-23-2013 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 Vin=12.0V, Vcc/LDO=5.3V, Vout1=3.3V, Io1=0.9A, Vout2=1.8V, Io2=0.3A, Room Temperature, No Air Flow 200 40 150 100 20 TR1/dB 0 0 -50 -20 TR2/° 50 -100 -150 -40 103 104 105 -200 f/Hz TR1: Mag(Gain) TR2: Unwrapped Phase(Gain) Fig.19: Bode Plot of CH2 at 0.3A load Bandwidth= 103.74Khz, Phase Margin= 55 degrees, Gain Margin =10.93dB 01-23-2013 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 Vin=12.0V, Vcc/LDO=5.3V, Vout1=3.3V, Io1=0.9A, Vout2 is disabled (EN2=low), Room Temperature, No Air Flow 94 92 90 Efficiency [%] 88 86 84 82 80 78 76 74 72 70 0 0.1 0.2 0.3 0.4 0.5 Io [A] 0.6 0.7 0.8 0.9 0 0.1 0.2 0.3 0.4 0.5 Io [A] 0.6 0.7 0.8 0.9 0.3 Power Loss [W] 0.25 0.2 0.15 0.1 0.05 0 Fig.20: Efficiency and power loss vs. load current for channel1 (Vout1 = 3.3V) 01-23-2013 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 [%] Efficiency and Power Loss of channel2 Vin=12.0V, Vcc/LDO=5.3V, Vout1 is disabled (EN1=low), Vout2=1.8V, Io2=0.3A, Room Temperature, No Air Flow 78 76 74 72 70 68 66 64 62 60 58 56 54 52 50 0 0.05 0.1 0.15 Io [A] 0.2 0.25 0.3 0 0.05 0.1 0.15 Io [A] 0.2 0.25 0.3 Power Loss [W] 0.2 0.15 0.1 0.05 0 Fig.21: Efficiency and power loss vs. load current for channel2 (Vout2 = 1.8V) 01-23-2013 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 Vin=12.0V, Vcc/LDO=5.3V, Vout1=3.3V, Io1= 0.9A, Vout2=1.8V, Io2=0.3A, Room Temperature, No Air Flow Fig.22: Thermal Image at Io1=0.9A, Io2=0.3A load Test Point 1: IR3891, Test Point 2: Inductor_Ch2, Test Point 3: Inductor_Ch1 01-23-2013 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 01-23-2013 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.