Issue 4 - June 2007

1

www.zetex.com

© Zetex Semiconductors plc 2007

ZXCT1032

High-side inrush controller and electronic fuse

Description

Ordering information

The ZXCT1032 is a high-side current monitor

that drives a PMOS or PNP transistor to

provide in-rush current limit and over-current

protection. The ZXCT1032 includes a high

accuracy high-side current monitor, a start-up

timer and a re-try inhibit timer.

The ZXCT1032 takes the voltage developed

across a current shunt resistor and compares

this with an externally set trip point. It works

in three modes:

•

Linear soft-start

•

Over-current detector

•

Over-current disconnect/fuse

Linear soft-start

Upon power up the ZXCT1032 enters a linear

soft-start mode. During which the output

current ramps up from zero to a maximum

user defined trip point. The trip point is set by

The soft start ensures that capacitive loads are

smoothly charged without causing excessive

power supply startup transients.

Over-current detectior

When external capacitor CT has charged up

soft-start mode to its over-current detection

mode. During this mode the external MOSFET

will be fully enhanced reducing the its voltage

drop and power dissipation.

While in this mode the internal current monitor

continually checks the output current and

compares it to the trip-current level determined

Over-current disconnect/fuse

If the trip current limit is exceeded at any time the

ZXCT1032 enters its Over-current disconnect

mode. The drive pin is driven high, turning the

pass MOSFET off; the flag output goes low

indicating a fault.

The drive and flag outputs are latched in these

internally set discharge current (3µA typical). After

restart into its linear soft-start mode.

ratioed to so that the power dissipation in the

pass MOSFET should allow indefinite operation

in the event of a continuous load failure.

Pin 3 description:

Determines the load current trip level or

constant current level. ISET can be left open

circuit (internal 2.1V reference) or driven via a

DC voltage or µC PWM output. Its source

impedance is 50k .

Features

•

Accurate high-side current sensing

•

User defined and dynamically adjustable

trip current

•

Load switch control

•

Fault flag logic output

•

User defined ramp and inhibit timers

•

SO8 package

•

Temperature range -40 to 85°C

Applications

•

Electronic fuse

•

Short circuit protected supply feed

•Hot swap

•

Power over twisted pair

Order code

Pack

Part mark

Reel size

Tape width

Quantity per reel

ZXCT1032N8TA

SO8

1032

7”

12mm

500