2-3

Pin Descriptions

PIN

DESIGNATOR

FUNCTION

DESCRIPTION

1

M12VIN

-12V Input

-12V Supply Input. Also provides power to the -12V overcurrent circuitry.

2

FLTN

Fault Output

5V CMOS Fault Output; LOW = FAULT. An optional capacitor may be place from this pin to

ground to provide additional immunity from power supply glitches.

3

3V5VG

3.3V/5V Gate Output

Drive the gates of the 3.3V and 5V MOSFETs. Connect a capacitor to ground to set the start-

up ramp. During turn on, this capacitor is charged with a 25

µA current source.

4

VCC

Connect to unswitched 12V supply.

5

12VIN

12V Input

Switched 12V supply input.

6

3VISEN

3.3V Current Sense

Connect to the load side of the current sense resistor in series with source of external 3.3V

MOSFET.

7

3VS

3.3V Source

Connect to source of 3.3V MOSFET. This connection along with pin 6 (3VISEN) senses the

voltage drop across the sense resistor.

8

OCSET

Overcurrent Set

Connect a resistor from this pin to ground to set the overcurrent trip point of all four switches. All

four over current trips can be programmed by changing the value of this resistor. The default

(6.04k

Ω, 1%) is compatible with the maximum allowable currents as outlined in the PCI specifi-

cation.

9

PWRON

Power On Control

Controls all four switches. High to Turn Switches ON, Low to turn them OFF.

10

5VS

5V Source

Connect to source of 5V MOSFET switch. This connection along with pin 11(5VISEN) senses

the voltage drop across the sense resistor.

11

5VISEN

5V Current Sense

Connect to the load side of the current sense resistor in series with source of external 5V MOSFET.

12

12VO

Switched 12V Output

Switched 12V output.

13

GND

Ground

Connect to common of power supplies.

14

12VG

Gate of Internal

PMOS

Connect a capacitor between 12VG and 12VO to set the start up ramp for the +12V supply.

This capacitor is charged with a 25

µA current source during start -up. The 3.3V and 5V UV

circuitry is enabled after the voltage on 12VG is less than 400mV. Therefore, if the capacitor

on the pin 3 (3V5VG) is more than 25% larger than the capacitor on pin 14 (12VG) a false UV

may be detected during start up.

15

M12VG

Gate of Internal

NMOS

Connect a capacitor between M12VG and M12VO to set the start up ramp for the M12V supply.

This capacitor is charged with 25

µA during start up.

16

M12VO

Switched -12V

Output

Switched 12V Output.

HIP1011