© 2000 Calirornia Micro Devices Corp. All rights reserved.

3/00

215 Topaz Street, Milpitas, California 95035

Tel: (408) 263-3214

Fax: (408) 263-7846

www.calmicro.com

CALIFORNIA MICRO DEVICES

CMPWR280

3

Interface Signals

V

Whenever V

(1500mA) will be enabled and deliver a fixed 3.3V at V

When V

will be disabled.

Internal loading on this pin is typically 1.5mA when the

regulator is enabled, which reduces to 0.2mA whenever

the regulator is disabled. If V

V

microamperes.

During a V

step increase in V

The amplitude of this step increase will depend on the dc

load current and any current required for charging/

discharging the load capacitance. This line current transient

will cause a voltage disturbance at the V

to the effective power supply source impedance being

delivered to the V

To prevent chatter during Select and Deselect transitions, a

built-in hysteresis voltage of 400mV has been incorporated.

It is recommended that the power supply connected to the

V

to minimize the chatter during the enabling/disabling of

the regulator.

V

selected on when V

regulator can deliver a maximum of 375mA load current.

Whenever V

provide all the internal bias currents and any necessary

regulator current.

GND is the reference for all voltages. The current that flows

in the ground connection is very low (typically 2.0mA) and

has minimal variation over all load conditions

V

the load. An output capacitor of ten microfarads is used to

provide the necessary phase compensation, thereby preventing

oscillation. This capacitor also helps to minimize the peak

output disturbance during power supply changeover.

When both V

provide the necessary quiescent current for the internal

reference circuits. This ensures excellent start-up characteristics

for the regulator.

Drive is an active LOW logic output intended to be used as

the control signal for driving an external P-channel MOSFET

switch whenever the regulator is disabled. This will allow the

voltage at V

(3.3V).

The Drive pin is pulled HIGH to V

enabled, thus ensuring that the auxiliary supply remains isolated

during normal regulator operation.

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