Philips Semiconductors

PIP401

OR-ing Intelligent Switch

Product data

Rev. 03 — 5 November 2002

3 of 16

9397 750 10578

© Koninklijke Philips Electronics N.V. 2002. All rights reserved.

The open-collector overtemperature flag output (TFL) is fed back to the remote

shutdown input of the protected supply. In a parallel redundant system, there will be

at least one other protected supply feeding the system bus via another or-ing device.

7.1 Supply voltage

5 V greater than the voltage on VI in order to supply sufficient drive voltage for the

series power switch. The maximum rated supply voltage is 20 V.

7.2 Voltage drop monitoring

7.2.1

Comparator

The comparator monitors the voltage between the input (VI) and the remote sense

input (VRS). When the voltage on VI is greater than the voltage on VRS by more than

a few millivolts, the comparator output goes HIGH, turning on the series power switch.

When the voltage on VI is less than the voltage on VRS, the series power switch is

turned off, blocking the flow of reverse current between VO and VI.

7.2.2

Remote sense input

The remote sense input (VRS) provides a high impedance connection to the load,

bypassing the power supply line inductance. This connection enables the PIP401 to

respond immediately to voltage changes at the load, removing the effects of voltage

transients induced in the power supply line inductance due to changes in load

current.

(2) D1 prevents reverse current flow from VO into the auxiliary supply in the event of failure

of the auxiliary supply.

(4) VRS should be connected to VO at the load point. Direct connection between VRS and

VO at the device pins should only be made if the distance between the PIP401 and the

load is very short, less than 25 mm.

Fig 2.

Functional circuit diagram.

VCC

VRS

GND

system bus

system bus ground

power supply shutdown

(open collector)

auxiliary supply

+20 V max

input voltage

from power supply

system

ground

03aj16

VO

VI

R1

(100

Ω typ)

C1

(100 nF)

D1

TFL