IRU3034 & (PbF)

3

www.irf.com

PIN DESCRIPTIONS

BLOCK DIAGRAM

Figure 2 - Simplified block diagram of the IRU3034.

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 1µF, 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.

This pin is connected to the minus side of the external current sense resistor. An internal

current source together with an external resistor in series with this pin programs the

current limit threshold voltage. This voltage divided by the external current sense resistor

sets the current limit threshold.

This pin is connected to the plus side of the external current sense resistor. A resistor in

series with this pin and a capacitor connected between this pin and pin 6 provides a high

frequency filtering for the noise spikes of turn on and turn off switching.

This pin provides the soft-start for the regulator during power up. It also sets a long off time

when the converter goes into current limiting, providing low duty cycle for the catch diode

allowing it to survive during short circuit.

PIN # PIN SYMBOL

PIN DESCRIPTION

1

2

3

4

5

6

7

8

Drv

Gnd

CS-

CS+

SS

UVLO

1.25V

PWM Control

CS+

Drv

Gnd

CS-

5

1

2

4

3

7

6

SS

8

5V Reg

S.S. / Hiccup

Control

20uA

R

3R