IRF IRDC3802A

IRDC3802A
SupIRBuck
TM
USER GUIDE FOR IR3802A EVALUATION BOARD
DESCRIPTION
The IR3802A 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 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.
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
1
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
Signal Name
VIN+
Vin (+12V)
VIN-
Ground of Vin
Vcc+
Optional Vcc input
Vcc-
Ground for Optional Vcc input
VOUT-
Ground of Vout
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
Vcc+
Connection Diagram
Vcc-
Vout+
Vin+
10mm/395mil’s
Vout-
Vin20mm/787mil’s
Front
Vcc-
Vcc+
Vout+
10mm/395mil’s
Vin+
Vout-
Vin20mm/787mil’s
Back
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
4
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
Fig. 6: Schematic of the IR3802A evaluation board
Ground and Signal ( “analog” ) Ground
Single point of connection between Power
IRDC3802A
6
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
Rev 0.1
6/9/2008
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
Manufacturer
Part Number
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
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
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
7
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
Efficiency (%)
90
85
80
75
70
0
1
2
3
4
5
6
7
6
7
Iout (A)
Fig.14: Efficiency versus load current
Power Loss for IR3802A at 12.0Vin, 3.3Vout
2.5
2.3
Ploss (W)
2.1
1.9
1.7
1.5
1.3
1.1
0.9
0.7
0.5
0
1
2
3
4
5
Iout (A)
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