6

ZXLB1600

TYPICAL APPLICATION CIRCUIT

APPLICATION NOTES

Increased efficiency

If the isolation of the coil from the supply is not needed, the SW pin can be connected to VIN to

improve efficiency. This prevents power loss in the internal high-side PMOS switch.

Low Battery Flag Output, LBF

This is an open drain output that switches low when the battery voltage falls below the detection

threshold. An external pull-up resistor can be connected to this pin to allow it to interface to any

voltage up to a maximum of 29V.

Layout considerations

The FB and LBT pins are high impedance inputs, so PCB track lengths to these should be kept as

short as possible. A small capacitor (~100pF) can be connected from the FB pin to the output to

reduce output ripple and noise. Also a capacitor can be connected from the LBT pin to ground to

minimise noise pickup into the low battery comparator if required.

DRAFT ISSUE J January 2002

ZXLB1600

VIN

LBF

EN

ADJ

LX

SW

SD

GND

FB

ZXLB1600

22uH

ZHCS500

OUTPUT

C1

LBT

SENSE