SupIRBuck TM IRDC3891 USER GUIDE FOR IRDC3891 EVALUATION BOARD DESCRIPTION BOARD FEATURES

Transcription

1 IRDC389 SupIRBuck TM USER GUIDE FOR IRDC389 EVUATION BOARD DESCRIPTION The IR389 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 IR389 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 IRDC389 evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for IR389 is available in the IR389 data sheet. BOARD FEATURES V in = +2.0V Fs = 600kHz V out = 4A L = 2.2uH V out2 = 4A L 2 =.5uH C out =4x22uF (ceramic 0805) C out2 =4x22uF (ceramic 0805) C in = 4x0uF (ceramic 206) + x330uf (electrolytic)

2 IRDC389 CONNECTIONS and OPERATING INSTRUCTIONS A well regulated +2.0V 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. and inputs and outputs of the board are listed in Table I. IR389 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 (Vout 2 ) 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 Vout 2. For normal operation (non-sequencing) Seq pin should be left floating. Seq pin is internally pulled up to 3.3V. Table I. Connections Connection VIN+ VIN- VOUT+ Signal Name PV in (+2V) Ground of PV in V out (+.8V) VOUT- Ground of Vout VOUT2+ V out2 (+.2V) VOUT2- Ground of Vout 2 LAYOUT VCC+ VCC- VSEQ EN, EN2 Sync VCC/LDO pin Connected to PGND Sequence input Enable input of each channel Synchronous input The PCB is a 4-layer board. All of layers are 2 Oz. copper. The IR389 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 IR389. The feedback resistors are connected to the output voltage at the point of regulation and are located close to IR389. To improve efficiency, the circuit board is designed to minimize the length of the on-board power ground current path

3 IRDC389 Connection Diagram V OUT V OUT2 GROUND GROUND PGood SEQ Vsns EN PGood2 Sync Vsns2 EN2 Vcc/LDO_out V in GROUND VPG Fig. : Connection diagram of IRDC389 evaluation board (top and bottom)

4 IRDC389 R50 is the Single point connection between AGND and PGND. Fig. 2: Board layout, top layer Fig. 3: Board layout, bottom layer

5 IRDC389 Fig. 4: Board layout, mid-layer I Fig. 5: Board layout, mid-layer II

6 IRDC389 6 Fig.6: Schematic of the IRDC389 evaluation board C226 C225 22uF Vout- VSeq C229 Vpg R7.54k Vsns C7 NS R6 4.02k Vout2- C22 0uF C2 0uF R2 49.9K C2 0.uF J2 JUMPER 2 V Vin C 0uF C2 0uF PGND + C 330uF/25V Input ceramic: 206 Vin+ Vin- Agnd Vin+ Vin- V2 L 2.2uH PGND Agnd R Agnd R2 Agnd R3.54k Vin R4 30 R2 4.02k R5 20 A Vpg B C3 2200pF R6 R8 Agnd VCC R K C27 NS C0 0.uF R k PGND Agnd C 0nF R4 PGood2 R9.8k R5 0 Vout Vcc+ R9 39.2K R 3.24k C23 C3 R0 0 C27 SYNC C26 C25 22uF C24 22uF C23 22uF Vin+ C22 22uF C20 0.uF R20 0 Vin- C8 2.2uF D DIODE Vsns2 L2.5uH SW C228 SW22 R8 84.5K R50 0 C28 R K R24 30 VCC R k Output ceramic: 0805 (use 206 footprint) R25 20 A2 B2 C pF U IR389 PVin2 5 PVin2 4 EN2 8 PGood2 2 Rt/Sync 7 Vin 3 Seq 6 Comp2 PGND2 6 Vsns Vcc/LDO 4 FB2 0 Boot2 3 GND 5 Vsns2 9 EN 2 PGND2 7 PGND2 8 SW2 9 SW2 20 SW 2 SW 22 PGND 23 PGND 24 PGND 25 PVin 26 Boot 28 PGood 29 PVin 27 Comp 30 FB 3 R 49.9K R3 0 C6.0uF C224 22uF SW VCC C223 22uF Vout+ Vout- C29 SW2 C6 NS C4 0.uF Agnd Agnd C26 NS C2 50pF C2 0nF R2 2.87K Vout+ C22 50pF PGood Vcc- R29.8k C9 R K C29 EN2 C7 Vout- C24 0.uF J JUMPER 2 Vpg C9 EN Vout2+ R7 Vout2- C22 0.uF Vin Vout2 Vout2+ Vout2- Vout+ Vout2+ C222 22uF C

7 IRDC389 Bill of Materials Vin=2.0V, Vout=.8V/4A, Vout2=.2V/4A, Fsw=600KHz Item Qty Part Reference Value Description Manufacturer Part Number C 330uF SMD Electrolytic F size 25V 20% Panasonic EEV-FKE33P 2 4 C C2 C2 C22 0uF 206, 25V, X5R, 0% TDK C326X5RE06K 3 C6.0uF 0603, 25V, X5R, 0% Murata GRM88R6E05KA2D 4 C8 2.2uF 0603, 6V, X5R, 20% TDK C608X5RC225M 5 6 C0 C4 C20 C24 C2 C22 0.uF 0603, 25V, X7R, 0% Murata GRM88R7E04KA0B 6 C 0nF 0603, 50V, X7R, 0% Murata GRM88R7H03KA0B 7 C2 50pF 0603, 50V, NP0, 5% Murata GRM885CH5JA0D 8 2 C3 C pF 0603, 50V, X7R, 0% Murata GRM88R7H222KA0B 9 C2 0nF 0603, 50V, X7R, 0% Murata GRM88R7H03KA0B 0 C22 50pF 0603, 50V, NP0, 5% Murata GRM885CH5JA0D 8 C22 C23 C24 C25 C222 C223 C224 C225 22uF 0805, 6.3V, X5R, 20% TDK C202X5R0J226M 2 L 2.2uH SMD 7.05x6.6x4.8mm,.2mΩ Cyntec PCMB065T-2R2MS 3 L2.5uH SMD 7.05x6.6x4.8mm,6.0mΩ Cyntec PCMB065T-R5MS 4 2 R R2 49.9K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF4992V 5 5 R3 R5 R0 R20 R50 0 Thick Film, 0603,/0W Panasonic ERJ-3GEY0R00V 6 R9 39.2K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF3922V 7 R 3.24K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF324V 8 2 R2 R6 4.02K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF402V 9 2 R3 R7.54K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF54V 20 R4 30 Thick Film, 0603,/0W,% Panasonic ERJ-3EKF300V 2 2 R5 R25 20 Thick Film, 0603,/0W,% Panasonic ERJ-3EKF20R0V 22 2 R8 R K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF8452V 23 2 R9 R29.8K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF82V 24 R2 2.87K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF287V 25 2 R22 R K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF402V 26 2 R23 R K Thick Film, 0603,/0W,% Panasonic ERJ-3EKF287V 27 R24 30 Thick Film, 0603,/0W,% Panasonic ERJ-3EKF300V 28 2 J J2 jumper This is a simple jumper 29 D Schottky, 40V, SOD-523 Vishay BAS40-02VGS08 30 U IR389 PQFN 5x6mm International Rectifier IR389MPBF

8 IRDC389 TYPIC OPERATING WAVEFORMS Vin=2.0V, Vcc/LDO=5.3V, Vout =.8V, Vout 2 =.2V, Io = Io 2 =0-4A, Room Temperature, No air flow Fig. 7: Start up at 4A Load (Note ) Ch :Vout, Ch 2 :Vout 2, Ch 3 :Vcc/LDO, Ch 4 :Vin Fig. 8: Start up at 4A Load (Note ) Ch :Vout, Ch 2 :Vout 2, Ch 3 :PGood, Ch 4 : PGood 2 Fig. 9: Start up with.05v Prebias, 0A Load Ch :Enable 2, Ch 2 :Vout 2, Ch 4 :PGood 2 Fig. 0: Start up with.52v Prebias, 0A Load Ch :Enable, Ch 2 :Vout, Ch 4 :PGood Fig. : Inductor switch node at 4A load / Channel Ch :SW, Ch 2 :SW Fig. 2: Output Voltage Ripple, 4A load/channel (Note2) Ch : Vout, Ch 2 : Vout 2 8

9 IRDC389 TYPIC OPERATING WAVEFORMS Vin=2.0V, Vcc/LDO=5.3V, Vout =.8V, Vout 2 =.2V, Room Temperature, No air flow Fig. 5: Transient Response of channel 0A-.6A (0-40%), Ch :Vout, Ch 2 :Vout 2, Ch 4 : Iout

10 IRDC389 TYPIC OPERATING WAVEFORMS Vin=2.0V, Vcc/LDO=5.3V, Vout =.8V, Vout 2 =.2V, Room Temperature, No air flow Fig. 6: Transient Response of channel2 0A-.6A (0-40%), Ch :Vout, Ch 2 :Vout 2, Ch 4 : Iout 2 Note: Enable is tied to Vin via a resistor divider. Note2: Vo ripple signal is taken across C25 and C225 capacitors

11 IRDC389 Bode Plot, Channel Vin=2.0V, Vcc/LDO=5.3V, Vout =.8V, Vout 2 =.2V, Io = Io 2 =4A, Room Temperature, No air flow Fig.7: Bode Plot of CH at 4A load: Fo = khz; Phase Margin = 5.88º

12 IRDC389 Bode Plot, Channel2 Vin=2.0V, Vcc/LDO=5.3V, Vout =.8V, Vout 2 =.2V, Io = Io 2 =4A, Room Temperature, No air flow Fig.8: Bode Plot of CH2 at 4A load: Fo = 3.06 khz; Phase Margin = 48.9º

13 IRDC389 Efficiency and Power Loss of channel Vin=2.0V, Vcc/LDO=5.3V, Vout =.8V, Vout 2 is disabled (EN2=low), Io = 0-4A, Room Temperature, No air flow Efficiency [%] Io [A] Power Loss [W] Io [A] Fig.9: Efficiency and power loss vs. load current for channel (Vout =.8V)

14 IRDC389 Efficiency and Power Loss of channel2 Vin=2.0V, Vcc/LDO=5.3V, Vout is disabled (EN=low), Vout 2 =.2V, Io 2 =0-4A, Room Temperature, No air flow Efficiency [%] Io [A] Power Loss [W] Io [A] Fig.20: Efficiency and power loss vs. load current for channel2 (Vout 2 =.2V)

15 IRDC389 Thermal Image Vin=2.0V, Vcc/LDO=5.3V, Vout=.8V, Vout2=.2V, Io= Io2=4A, Room Temperature, No air flow Fig.2: Thermal Image at Io=Io2=4A load Test Point : IR389, Test Point 2: Inductor_Ch, Test Point 3: Inductor_Ch

16 IRDC389 IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (30) TAC Fax: (30) Visit us at for sales contact information Data and specifications subject to change without notice