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IRDC3802A
SupIRBuck
DESCRIPTION
TM
USER GUIDE FOR IR3802A EVALUATION BOARD
The IR3802A 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 IR3802A include programmable soft-start ramp, precision 0.6V reference voltage, programmable thermal protection, fixed 300kHz 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 IR3802A evaluation board. The guide describes operation and use of the evaluation board itself. Detailed application information for IR3802A is available in the IR3802A data sheet.
BOARD FEATURES * Vin = +12V (13.2V Max) * Vout = +3.3V @ 0- 6A *L=
3.3uH
* Cin= 1x10uF (ceramic 1206), 1x47uF (PosCap, 16V) * Cout= 1x22uF (ceramic 0805), 1x220uF/6.3V (SP-Cap)
Rev 0.1 6/9/2008
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IRDC3802A
CONNECTIONS and OPERATING INSTRUCTIONS
A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum 6A 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. IR3802A has two input supplies, one for biasing (Vcc) and the other as input voltage (Vin). These inputs are connected on the board with a 0 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 6/9/2008
2
IRDC3802A
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 6/9/2008
3
IRDC3802A
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 6/9/2008
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IRDC3802A
Fig. 4: Board layout, mid-layer I.
Fig. 5: Board layout, mid-layer II.
Rev 0.1 6/9/2008
5
Rev 0.1 6/9/2008
Single point of connection between Power
Ground and Signal ( "analog" ) Ground
IRDC3802A
Fig. 6: Schematic of the IR3802A evaluation board
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IRDC3802A
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 1 1 3 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 B1 C1 C2 C12 C14 C3 C6 C7 C8 C9 C10 C13 C15 C16 D2 L1 R1 R2 R3 R12 R4 R6 R13 U1 Value ESDB016,Rev A 10uF 0.1uF 47uF 22pF 1500pF 680pF 330pF 0.22uF 1uF 22uF 220uF BAT54WS 3.3uH 30.1K 45.3K 10K 2.2K 20 0.0 IR3802A 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,5% Ceramic,50V,C0G,5% Ceramic,50V,0603,X7R,10% Ceramic,10V,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,0805,1/16W,5% IR3802A, Controller,PQFN,5x6mm Manufacturer International Rectifier TDK Corporation Panasonic - ECG Sanyo Panasonic - ECG Murata Panasonic - ECG Murata Panasonic - ECG Panasonic - ECG TDK Panasonic International Rectifier ACT Rohm Panasonic - ECG Vishey/Dale Rohm Vishey/Dale Panasonic - ECG International Rectifier Part Number ESDB016,Rev A C3216X7R1C106K ECJ-1VB1E104K 16TQC47M ECJ-1VC1H220J GRM1885C1H152JA01D ECJ-1VC1H681J GRM188R71H331MA01D ECJ-1VB1A224K ECJ-BVB1C105K C2012X5R0J226M EEFUE0G221XE BAT54WS STS704-3R3M MCR03EZPFX3012 ERJ-3EKF4532V CRCW060310K0FKEA MCR03EZPFX2201 CRCW060320R0FKEA ERJ-6GEY0R00V IR3802A
Rev 0.1 6/9/2008
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IRDC3802A
TYPICAL OPERATING WAVEFORMS Vin=Vcc=12.0V, Vo=3.3V, Io=0- 6A, Room Temperature, No Air Flow
Fig. 7: Start up at 6A 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, 6A load Ch1: Vout ,Ch4: Iout
Fig. 10: Inductor node at 6A load Ch1:LX, Ch4:Iout
Fig. 11: Short (Hiccup) Recovery Ch1:VSS , Ch2:Vout
Rev 0.1 6/9/2008
8
IRDC3802A
TYPICAL OPERATING WAVEFORMS Vin=Vcc=12.0V, Vo=3.3V, Io=0- 6A, Room Temperature, No Air Flow
Fig. 12: Transient Response, 3A to 6A step Ch1:Vout, Ch4:Iout
Rev 0.1 6/9/2008
9
IRDC3802A
TYPICAL OPERATING WAVEFORMS Vin=Vcc=12.0V, Vo=3.3V, Io=0- 6A, Room Temperature, No Air Flow
Fig. 13: Bode Plot at 6A load shows a bandwidth of 30+kHz and phase margin of 62+degrees
Rev 0.1 6/9/2008
10
IRDC3802A
TYPICAL OPERATING WAVEFORMS Vin=Vcc=12.0V, Vo=3.3V, Io=0- 6A, Room Temperature, No Air Flow
Efficiency for IR3802A at 12.0Vin, 3.3Vout
95 90 Efficiency (%) 85 80 75 70 0 1 2 3 Iout (A) 4 5 6 7
Fig.14: Efficiency versus load current
Power Loss for IR3802A at 12.0Vin, 3.3Vout
2.5 2.3 2.1 1.9 Ploss (W) 1.7 1.5 1.3 1.1 0.9 0.7 0.5 0 1 2 3 Iout (A) 4 5 6 7
Fig.15: Power loss versus load current
Rev 0.1 6/9/2008
11
IRDC3802A
TYPICAL OPERATING WAVEFORMS Vin=Vcc=12.0V, Vo=3.3V, Io=0- 6A, Room Temperature, No Air Flow
Fig. 17: Thermal Image at 6A load at 74o C Test point (square) 2 is IR3802A
Rev 0.1 6/9/2008
12
IRDC3802A
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 6/9/2008
IRDC3802A
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 6/9/2008
IRDC3802A
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 6/9/2008
IRDC3802A
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 6/9/2008

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