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IRDC3802
SupIRBuck
DESCRIPTION
TM
USER GUIDE FOR IR3802 EVALUATION BOARD
The IR3802 is a synchronous buck converter, providing a compact, high performance and flexible solution in a small 5mmx6mm Power QFN package. Key features offered by the IR3802 include programmable soft-start ramp, precision 0.6V reference voltage, thermal protection, fixed 600kHz switching frequency requiring no external component, input under-voltage lockout for proper start-up, and pre-bias start-up.
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. This user guide contains the schematic and bill of materials for the IR3802 evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for IR3802 is available in the IR3802 data sheet.
BOARD FEATURES * Vin = +12V (13.2V Max) * Vout = +3.3V @ 0- 4A *L=
3.3uH
* Cin= 1x10uF (ceramic 1206) * Cout= 1x22uF (ceramic 0805), 1x220uF/6.3V (SP-Cap)
Rev 0.1 6/16/2008
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IRDC3802
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. IR3802 has two input supplies, one for biasing (Vcc) and the other as input voltage (Vin). These inputs are connected on the board with a 330 ohm resistor (R13). Separate supplies can be applied to these inputs. Vcc input cannot be connected unless R13 is removed. Vcc input should be a well regulated 5V-12V supply and it would be connected to Vcc+ and Vcc-.
Table I. Connections
Connection VIN+ VINVcc+ VccVOUTVOUT+ Signal Name Vin (+12V) Ground of Vin Optional Vcc input Ground for Optional Vcc input Ground of Vout Vout (+3.3V)
LAYOUT
The PCB is a 4-layer board. All of layers are 2 Oz. copper. The IR3802A SupIRBuck and all of the passive components are mounted on the bottom side of the board. The Inductor, Input and Output Bulk Capacitors are located on the top side of the board. Power supply decoupling capacitors, the charge-pump capacitor and feedback components are located close to IR3802A. 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. Rev 0.1 6/16/2008
2
IRDC3802
Connection Diagram
Vcc+ Vin+
Vcc-
Vout+
10mm/395mil's
Vin20mm/787mil's Front
Vout-
VccVout+
10mm/395mil's
Vcc+ Vin+
Vout20mm/787mil's Back
Vin-
Fig. 1: Connection diagram of IR3802A evaluation board
Rev 0.1 6/16/2008
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IRDC3802
Fig. 2: Board layout, top overlay
Single point connection between AGND and PGND.
PGND Plain
PGND Plain
Fig. 3: Board layout, bottom overlay (rear view) Rev 0.1 6/16/2008
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IRDC3802
Fig. 4: Board layout, mid-layer I.
Fig. 5: Board layout, mid-layer II.
Rev 0.1 6/16/2008
5
Rev 0.1 6/16/2008
Single point of connection between Power
Ground and Signal ( "analog" ) Ground
IRDC3802
Fig. 6: Schematic of the IR3802 evaluation board
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IRDC3802
Bill of Materials
Item Number 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 1 1 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 B1 C1 C2 C12 C14 C3 C6 C7 C8 C9 C10 C13 C15 C16 D2 L1 R1 R2 R3 R4 R6 R12 R13 U1 Value ESDB016,Rev A 10uF 0.1uF 47uF 22pF 1000pF 820pF 560pF 0.22uF 1uF 22uF 220uF BAT54WS 3.3uH 36.0K 28.7K 6.34K 1.8K 20 8.06K 330 IR3802 Description ESDB016,Rev A, PCB Ceramic,16V,1206,X7R,10% Ceramic,25V,0603,X7R,10% Poscap,16V,D2,Polomer-Aluminum Ceramic,50V,0603,NPO,5% Ceramic,50V,0603,C0G,10% Ceramic,50V,0603,X7R,10% Ceramic,50V,0603,X7R,10% Ceramic,10V,0603,X5R,10% Ceramic,16V,0603,X5R,10% Ceramic,6.3V,0805,X5R,20% SP-Cap,4.0V,D4,Polymer-Aluminum Diode,Schotky,40V,SOD323,200mA SMT-Inductor,18mOhms,7.5x7.5mm,20% 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,0603,1/10 W,1% Thick-film,0603,1/10 W,1% Thick-film,0805,1/8W,1% IR3802, Controller,PQFN,5x6mm Manufacturer International Rectifier TDK Corporation Panasonic - ECG Sanyo Panasonic - ECG Kemet Murata Murata Panasonic - ECG Panasonic - ECG TDK Panasonic International Rectifier ACT Panasonic - ECG Rohm Rohm Rohm Vishey/Dale Rohm Rohm International Rectifier Part Number ESDB016,Rev A C3216X7R1C106K ECJ-1VB1E104K 16TQC47M ECJ-1VC1H220J C0603C102J5GACTU GRM188R71H821KA01D GRM188R71H561KA01D ECJ-1VB1A224K ECJ-BVB1C105K C2012X5R0J226M EEFUE0G221XE BAT54WS STS704-3R3M ERJ-3EKF3602V MCR03EZPFX2872 MCR03EZPFX6341 MCR03EZPFX1801 CRCW060320R0FKEA MCR03EZPFX8061 MCR10EZPF3300 IR3802
Rev 0.1 6/16/2008
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IRDC3802
TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vcc = 6.3V, Vo=3.3V, Io=0- 4A, Room Temperature, No Air Flow
Fig. 7: Start up at 4A Load Ch1:Vin, Ch2:VSS, Ch3:Vout, Ch4:Iout
Fig. 8: Pre-Bias Start up, 0A Load Ch1:Vin, Ch2:VSS, Ch3:Vout
Fig. 9: Output Voltage Ripple, 4A load Ch1: Vout ,Ch4: Iout
Fig. 10: Inductor node at 4A load Ch1:LX, Ch4:Iout
Fig. 11: Short (Hiccup) Recovery Ch1:VSS , Ch2:Vout
Rev 0.1 6/16/2008
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IRDC3802
TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vcc = 6.3V, Vo=3.3V, Io=0- 4A, Room Temperature, No Air Flow
Fig. 12: Transient Response, 2A to 4A step Ch1:Vout, Ch4:Iout
Rev 0.1 6/16/2008
9
IRDC3802
TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vcc = 6.3V, Vo=3.3V, Io=0- 4A, Room Temperature, No Air Flow
Fig. 13: Bode Plot at 4A load shows a bandwidth of 32+kHz and phase margin of 52+degrees
Rev 0.1 6/16/2008
10
IRDC3802
TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vcc = 6.3V, Vo=3.3V, Io=0- 4A, Room Temperature, No Air Flow
Efficiency for IR3802 at 12.0Vin, 3.3Vout and R13 = 330
92 90 88 Efficiency (%) 86 84 82 80 78 76 74 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Iout (A)
Fig.14: Efficiency versus load current
Power Loss for IR3802 at 12.0Vin, 3.3Vout, and R13 = 330
1.6 1.4 1.2 Ploss (W) 1.0 0.8 0.6 0.4 0.2 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Iout (A)
Fig.15: Power loss versus load current
Rev 0.1 6/16/2008
11
IRDC3802
TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vcc = 6.3V, Vo=3.3V, Io=0- 4A, Room Temperature, No Air Flow
Fig. 16: Thermal Image at 4A load at 50.4o C Test point (square) 1 is IR3802
Rev 0.1 6/16/2008
12
IRDC3802
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.
Rev 0.1 6/16/2008
IRDC3802
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.
Rev 0.1 6/16/2008
IRDC3802
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.
*
Rev 0.1 6/16/2008
IRDC3802
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 Rev 0.1 6/16/2008

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