CALIFORNIA MICRO DEVICES

3/6/2001

3

215 Topaz Street, Milpitas, California 95035



Tel: (408) 263-3214

Fax: (408) 263-7846

www.calmicro.com

CMPWR330

©2001 California Micro Devices Corp. All rights reserved. Smart OR™ is a trademark of California Micro Devices.

Interface Signals

V

Whenever this supply voltage exceeds the V

(4.4V), it will immediately be given priority and be used

to power the regulator output. If this supply voltage falls

below the V

deselected and no longer provide power for the regula-

tor output. An internal hysteresis voltage of 0.2V is used

to prevent any chatter during selection and deselection

of V

kept below 0.3

Ω to ensure changeover disturbances do

not exceed the hysteresis level.

If the connection to V

the main input filter, a bypass capacitor may not be

necessary. Otherwise a bypass filter capacitor in the

range of 1µF to 10µF will ensure adequate filtering.

V

ately used to power the regulator output whenever V

below the deselect level (4.2V).

If the V

main input filter, a bypass capacitor may not be neces-

sary. Otherwise a bypass filter capacitor in the range of

1µF to 10µF will ensure adequate filtering.

V

selected only when V

not present. Under these conditions an internal switch is

enabled and provides a very low impedance connection

directly between V

V

regulator or via the low impedance auxiliary switch. This

output requires a capacitance of 10µF to ensure regula-

tor stability and minimize the peak output disturbance

during power supply changeover.

GND provides the reference for all voltages.

INTERFACE SIGNALS

Pin

Symbol

Description

1

2

Primary supply voltage (5V) input for regulator

3

4

Auxiliary supply voltage (3.3V) input for low impedance switch

5 - 8

GND

Reference for all voltages

Simplified Electrical Schematic

3.3V

400mA

3.3V

+

–

+

+

–

4.2V

CONTROLLER

REGULATOR AMP

ENABLE

GND

GND

0.25

Ω