IRDC3831

2

02/10/09

A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum ±8A 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.

IR3831 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

should not exceed Vcc.

CONNECTIONS and OPERATING INSTRUCTIONS

LAYOUT

The PCB is a 4-layer board. All of layers are 2 Oz. copper. The IR3831 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 IR3831. 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.

Table I. Connections

Tracking Input

V

DDQ

V

VOUT+

Ground for Vcc input

Vcc-

Vcc input

Vcc+

Enable

Enable

Power Good Signal

PGood

Ground of V

out

VOUT-

Ground of V

in

VIN-

V

VIN+

Signal Name

Connection