IRDC3832W SupIRBuck TM USER GUIDE FOR IR3832W EVALUATION BOARD DESCRIPTION The IR3832W is a synchronous buck converter, providing a compact, high performance and flexible solution in a small 5mmx6mm Power QFN package. An 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. Key features offered by the IR3832W include programmable soft-start ramp, thermal protection, Power Good, programmable switching frequency, tracking input, enable input, input under-voltage lockout for proper start-up, and pre-bias start-up. This user guide contains the schematic and bill of materials for the IR3832W evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for IR3832W is available in the IR3832W data sheet. BOARD FEATURES • Vin = +12V (13.2V Max) • Vcc= +5V (5.5V Max) • Vout = +0.75V @ 0- ±4A • Fs = 400kHz • L = 1.50uH • Cin= 2x10uF (ceramic 1206) + 330uF (electrolytic) • Cout= 6x22uF (ceramic 0805) 10/30/09 1 IRDC3832W CONNECTIONS and OPERATING INSTRUCTIONS A well regulated +12V 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. IR3832W has two input supplies, one for biasing (Vcc) and the other as input voltage (Vin). Separate supplies should be applied to these inputs. Vcc input should be a well regulated 4.5V-5.5V supply and it would be connected to Vcc+ and Vcc-. If single 12V application is required, connect R7 ( zero Ohm resistor) which enables the on board bias regulator (see schematic). In this case there is no need of external Vcc supply. The output tracks VDDQ input. The value of R14 and R28 can be selected to provide the desired ratio between the output voltage and the tracking input. For proper operation of IR3832W, the voltage at Vp pin should not exceed Vcc. Table I. Connections Connection Signal Name VIN+ Vin (+12V) VIN- Ground of Vin Vcc+ Vcc input Vcc- Ground for Vcc input VOUT- Ground of Vout VOUT+ Vout (+0.75V) Enable Enable VDDQ Tracking Input PGood Power Good Signal LAYOUT The PCB is a 4-layer board. All of layers are 2 Oz. copper. The IR3832W SupIRBuck and all of the passive components are mounted on the top side of the board. Power supply decoupling capacitors, the Bootstrap capacitor and feedback components are located close to IR3832W. The feedback resistors are connected to the output voltage at the point of regulation and are located close to the SupIRBuck. To improve efficiency, the circuit board is designed to minimize the length of the on-board power ground current path. 10/30/09 2 IRDC3832W Connection Diagram Vin GND Enable Vp GND VDDQ AGND Vo PGood SS Vcc GND Fig. 1: Connection diagram of IR383xW evaluation boards 10/30/09 3 IRDC3832W Fig. 2: Board layout, top overlay Fig. 3: Board layout, bottom overlay 10/30/09 4 IRDC3832W AGND Plane PGND Plane Single point connection between AGND and PGND. Fig. 4: Board layout, mid-layer I Fig. 5: Board layout, mid-layer II 10/30/09 5 Vcc- PGood 1 1 1 R17 10.0K Vcc+ R28 1.50K VCC C23 10nF R1 3.48K Agnd R9 35.7K SS Vp C10 22000pF C26 10000pF C11 220pF 1 1 R14 1.50K 1 1 7 6 5 4 3 2 Vp 1 R19 7.50k 13 IR3832W R3 N/S 6.65K R2 210 R4 C13 0.1uF VCC PGnd SW Vin 10 11 12 A C24 0.1uF 20 R6 C8 2200pF PGND R10 0 49.9K B 0 R* L1 1.5uH + Vin N/S N/S N/S N/S N/S R7 C35 N/S C21 C22 C27 Ground and Signal ( “analog” ) Ground D1 MM3Z5V6B C15 + C34 0.1uF Vcc 22uF 22uF Optional +5V supply for Vcc C32 0.1uF R5 3.30K Q1 MMBT3904-TP 22uF 22uF 22uF C16 N/S C17 C2 10uF C3 10uF C4 C18 C19 + C36 N/S 22uF C20 N/S N/S 0.1uF C28 C5 C6 C7 Single point of connection between Power R12 2.74k 1 Fig. 6: Schematic of the IR3832W evaluation board OCset SS Rt AGnd1 COMP FB Vp U1 C25 N/S 1 14 Enable PGood 8 Boot Vcc 9 AGnd3 15 R18 1 Enable 1 VDDQ 2 10/30/09 1 1 1 Vin+ Vin+ 1 1 1 1 C14 0.1uF Vout 1 Vout- Vout- Vout+ Vout+ Vin- 330uF Vin1 C1 Vin IRDC3832W 6 IRDC3832W Bill of Materials Item Quantity Part Reference 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 1 2 1 1 5 1 1 6 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 C1 C2 C3 C10 C34 C7 C13 C14 C24 C32 C8 C11 C15 C16 C17 C18 C19 C20 C25, C26 D1 L1 Q1 R5 R18 R4 R6 R9 R12 R17 R19 R10 R1 R2 R14, R28 U1 10/30/09 Value Description Manufacturer Part Number 330uF 10uF 0.022uF 10uF 0.1uF 2200pF 220pF 22uF 10000pF MM3Z5V6B 1.5uH MMBT3904/SOT 3.3k 49.9k 210 20 35.7k 2.74k 10.0k 7.5k 0 3.48k 6.65k 1.50k IR3832W SMD Elecrolytic, Fsize, 25V, 20% 1206, 16V, X5R, 20% 0603, 16V, X7R, 10% 0805, 10V, X5R, 20% 0603, 25V, X7R, 10% 0603, 50V, NP0, 5% 0603, 50V, NP0, 5% 0805, 6.3V, X5R, 20% 0603, 50V, X7R, 10% Zener, 5.6V 11.5x10x4mm, 20%, 3.9mOhm NPN, 40V, 200mA, SOT-23 Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10 W,1% Thick Film, 0603,1/10W,1% Thick Film, 0603,1/10 W,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% 4A SupIRBuck, 6mmx5mm Panasonic Panasonic - ECG Panasonic- ECG Panasonic - ECG Panasonic - ECG Murata Panasonic- ECG Panasonic- ECG Panasonic - ECG Fairchild Delta Fairchild Rohm Rohm Panasonic - ECG Vishey/Dale Rohm Rohm Rohm Rohm Yageo Rohm Rohm Rohm International Rectifier EEV-FK1E331P ECJ-3YB1C106M ECJ-1VB1C223K ECJ-GVB1A106M ECJ-1VB1E104K GRM1885C1H222JA01D ECJ-1VC1H221J ECJ-2FB0J226M ECJ-1VB1H103K MM3Z5V6B MPO104-1R5IR MMBT3904/SOT MCR03EZPFX3301 MCR03EZPFX4992 ERJ-3EKF2100V CRCW060320R0FKEA MCR03EZPFX3572 MCR03EZPFX2741 MCR03EZPFX1002 MCR03EZPFX7501 RC0603FR-100RL MCR03EZPFX3481 MCR03EZPFX6651 MCR03EZPFX1501 IR3832WMPbF 7 IRDC3832W TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vcc=5V, Vo=0.75V, Io=0- ±4A, Room Temperature, No Air Flow Fig. 7: Start up at 4A, sourcing current Ch1:PGood, Ch2:Vout, Ch3:VDDQ, Ch4:SS Fig. 8: Start up with Prebias, 0A Load Ch1:PGood, Ch2:Vout,Ch3:VDDQ, Ch4:SS Fig. 9: Inductor node at 4A, sourcing current, Ch3:SW, Ch4:Iout Fig. 10: Inductor node at -3A, sinking current, Ch3:SW , Ch4:Iout Fig. 11: Output Voltage Ripple, 4A, sourcing current, Ch2: Vout Fig. 12: Short (Hiccup) Recovery Ch2:Vout, Ch3:VSS , Ch4:PGood 10/30/09 8 IRDC3832W TYPICAL OPERATING WAVEFORMS Vin=12V, Vcc=5V, Vo=0.75V, Room Temperature, No Air Flow Fig. 13: Tracking 4A, sourcing current, Ch2:Vout, Ch3:VDDQ, Ch4:PGood Fig. 14: Tracking -3A load, sinking current, Ch2:Vout, Ch3:VDDQ, Ch4:PGood Fig. 15: Transient Response, 1A/us -0.5A to +0.5A load , Ch2:Vout, Ch4:Io 10/30/09 9 IRDC3832W TYPICAL OPERATING WAVEFORMS Vin=12V, Vcc=5V, Vo=0.75V, Io=+4A, Room Temperature, No Air Flow Fig.16: Bode Plot at 4A load (sourcing current) shows a bandwidth of 65kHz and phase margin of 60 degrees 10/30/09 10 IRDC3832W TYPICAL OPERATING WAVEFORMS Vin=12V, Vo=0.75V, Io=0- +4A, Room Temperature, No Air Flow 89 88 87 Efficiency (%) 86 85 84 83 82 81 80 79 10 20 30 40 50 60 70 80 90 100 Load Percentage (%) Fig.17: Efficiency versus load current 0.55 0.50 0.45 Power Loss (W) 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 10 20 30 40 50 60 70 80 90 100 Load Percentage(%) Fig.18: Power loss versus load current 10/30/09 11 IRDC3832W THERMAL IMAGES Vin=12V, Vo=0.75V, Io=+4A, Room Temperature, No Air Flow Fig.19: Thermal Image at 4A load Test Point 1: IR3832W, Test Point 2: Inductor 10/30/09 12 IRDC3832W PCB Metal and Components Placement The lead lands (the 11 IC pins) width should be equal to the nominal part lead width. The minimum lead to lead spacing should be ≥ 0.2mm to minimize shorting. Lead land length should be equal to the maximum part lead length + 0.3 mm outboard extension. The outboard extension ensures a large and inspectable toe fillet. The pad lands (the 4 big pads other than the 11 IC pins) length and width should be equal to maximum part pad length and width. However, the minimum metal to metal spacing should be no less than 0.17mm for 2 oz. Copper; no less than 0.1mm for 1 oz. Copper and no less than 0.23mm for 3 oz. Copper. 10/30/09 IRDC3832W Solder Resist It is recommended that the lead lands are Non Solder Mask Defined (NSMD). The solder resist should be pulled away from the metal lead lands by a minimum of 0.025mm to ensure NSMD pads. The land pad should be Solder Mask Defined (SMD), with a minimum overlap of the solder resist onto the copper of 0.05mm to accommodate solder resist mis-alignment. Ensure that the solder resist in between the lead lands and the pad land is ≥ 0.15mm due to the high aspect ratio of the solder resist strip separating the lead lands from the pad land. 10/30/09 IRDC3832W Stencil Design • • The Stencil apertures for the lead lands should be approximately 80% of the area of the lead lads. Reducing the amount of solder deposited will minimize the occurrences of lead shorts. If too much solder is deposited on the center pad the part will float and the lead lands will be open. The maximum length and width of the land pad stencil aperture should be equal to the solder resist opening minus an annular 0.2mm pull back to decrease the incidence of shorting the center land to the lead lands when the part is pushed into the solder paste. 10/30/09 IRDC3832W BOTTOM VIEW 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 Consumer market. Visit us at www.irf.com for sales contact information Data and specifications subject to change without notice. 11/07 10/30/09