IRDC3821A International Rectifier, IRDC3821A Datasheet - Page 2

• Manufacturer Part Number: IRDC3821A
• Description: BOARD EVAL SYNC BUCK CONVERTER
• Manufacturer: International Rectifier

CONNECTIONS and OPERATING INSTRUCTIONS
A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum 9A 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.
IR3821A has two input supplies, one for biasing (Vcc) and the other as input voltage (Vin). These inputs are
connected on the board with a zero ohm resistor (R15). Separate supplies can be applied to these inputs.
Vcc input cannot be connected unless R15 is removed.
and it would be connected to Vcc+ and Vcc-.
LAYOUT
The PCB is a 4-layer board. All of layers are 2 Oz. copper. The SupIRBuck and all of the passive
components are mounted on the top side of the board.
Power supply decoupling capacitors, the charge-pump capacitor and feedback components are located
close to the IR3821A. The feedback resistors are connected to the output voltage at the point of
regulation and are located close to the SupIRBuck.
The input and output energy storage capacitors and the power inductor are located on top side of the
board, these are connected to IR3821A through vias. To improve efficiency, the circuit board is
designed to minimize the length of the on-board power ground current path.
Rev 0.0
01/07/2008
Connection
VIN+
VIN-
Vcc+
Vcc-
VOUT-
VOUT+
P_Good
Table I. Connections
Signal Name
V
Ground of V
Optional Vcc input
Ground for Optional Vcc input
Ground of V
V
Power Good Signal
in
out
(+12V)
(+1.8V)
Vcc input should be a well regulated 5V-12V supply
in
out
IRDC3821A
2