IRU3033

3

Rev. 1.7

07/17/02

www.irf.com

PIN DESCRIPTIONS

BLOCK DIAGRAM

Figure 2 - Simplified block diagram of the IRU3033.

The PWM output of the switching controller. This pin is a totem pole drive that is con-

nected to the gate of the power MOSFET. A resistor may be placed from this pin to the

gate in order to reduce switching noise.

This pin supplies the voltage to the PWM drive and hysteresis circuitry and it is connected

to the 12V supply. A 1

mF, high frequency capacitor must be connected from this pin to

ground to provide the peak current for charging and discharging of the MOSFET.

A resistor divider from this pin to the output of the switching regulator and ground sets the

Core supply voltage.

ripple voltage for the switching regulator.

This pin is connected to the IC substrate and must be connected to the lowest potential in

the system.

The feedback pin of the linear regulator. A resistor divider from this pin to the output of the

linear regulator and ground sets the I/O supply voltage.

The drive pin of the linear regulator. This pin controls the base of a transistor or the gate

of a MOSFET acting as the series pass element for the linear regulator.

This pin provides the biasing for the chip and drive for the linear regulator controller. It is

connected to 12V supply. A 10

V resistor in series from this pin to the 12V supply and a

1

mF, high frequency capacitor connected from this pin to ground is required to filter the

switching noise of the switching regulator.

PIN #

PIN SYMBOL

PIN DESCRIPTION

1

2

3

4

5

6

7

8

Drv1

Gnd

Drv2

UVLO

1.25V

PWM Control

Drv 1

Gnd

Drv2

5

1

2

4

3

6

7

8

5V Reg