IRDC3841W

10/26/2009

2

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.

IR3841W 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.

and R28 can be selected to provide the desired ratio between the output voltage and the tracking input. For

proper operation of IR3841W, the voltage at Seq. pin should not exceed Vcc.

CONNECTIONS and OPERATING INSTRUCTIONS

LAYOUT

The PCB is a 4-layer board. All of layers are 2 Oz. copper. The IR3841W 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 IR3841W. 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

Sequence Input

Seq.

V

VOUT+

Ground for Vcc input

Vcc-

Vcc input

Vcc+

Enable

Enable

Power Good Signal

P_Good

Ground of V

out

VOUT-

Ground of V

in

VIN-

V

VIN+

Signal Name

Connection