© 1999 California Micro Devices Corp. All rights reserved.

9/99

215 Topaz Street, Milpitas, California 95035

Tel: (408) 263-3214

Fax: (408) 263-7846

www.calmicro.com

3

CMPWR150

CALIFORNIA MICRO DEVICES

Interface Signals

V

monitored continuously by an internal controller circuit.

Whenever V

regulator (500mA max) will be enabled and deliver a fixed

3.3V at V

the regulator will be disabled

Internal loading on this pin is typically 1.0mA when the

regulator is enabled, which reduces to 0.15mA whenever

the regulator is disabled. If V

the V

few microamperes.

During a V

step increase in V

enabled. The amplitude of this step increase will depend

on the dc load current and any necessary current required

for charging/discharging the load capacitance. This line

current transient will cause a voltage disturbance at the V

CC

pin. The magnitude of the disturbance will be directly

proportional 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 250mV has been incorporated.

It is recommended that the power supply connected to

the V

0.25Ω to minimize the event of chatter during the enabling/

disabling of the regulator.

An input filter capacitor in close proximity to the V

will reduce the effective source impedance and help

minimize any disturbances. If the V

inches of the main input filter, a capacitor may not be

necessary. Otherwise an input filter capacitor in the range

of 1uF to 10uF will ensure adequate filtering.

GND is the negative reference for all voltages. The current

that flows in the ground connection is very low (typically

1.0mA) and has minimal variation over all load conditions.

V

power the load. An output capacitor of ten microfarads is

used to provide the necessary phase compensation, thereby

preventing oscillation. The capacitor also helps to minimize

the peak output disturbance during power supply

changeover.

When V

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 PFET whenever

the regulator is disabled. This will allow the voltage at V

OUT

to be powered from an auxiliary supply voltage (3.3V).

The Drive pin is pulled HIGH to V

is enabled. This ensures that the auxiliary remains isolated

during normal regulator operation.

n.c. pins are electrically isolated from the internal circuitry.

These pins can be connected to any external voltage level

without impacting the device funtionality.

S

N

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