LM2787

Low Noise Regulated Switched Capacitor Voltage

Inverter in micro SMD

General Description

The LM2787 CMOS Negative Regulated Switched Capacitor

Voltage Inverter delivers a very low noise adjustable output

for an input voltage in the range of +2.7V to +5.5V. Four low

cost capacitors are used in this circuit to provide up to 10mA

of output current. The regulated output for the LM2787 is

adjustable between −1.5V and −5.2V. The LM2787 operates

at 260 kHz (typical) switching frequency to reduce output

resistance and voltage ripple. With an operating current of

only 400 µA (charge pump power efficiency greater than

90% with most loads) and 0.05 µA typical shutdown current,

the LM2787 provides ideal performance for cellular phone

power amplifier bias and other low current, low noise nega-

tive voltage needs. The device comes in a small 8-Bump

micro SMD package.

Features

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Inverts and regulates the input supply voltage

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Small 8-Bump micro SMD package

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91% typical charge pump power efficiency at 10mA

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Low output ripple

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Shutdown lowers Quiescent current to 0.05 µA (typical)

Applications

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Wireless Communication Systems

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Cellular Phone Power Amplifier Biasing

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Interface Power Supplies

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Handheld Instrumentation

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Laptop Computers and PDA’s

Typical Application Circuit and Connection Diagram

10131325

8-Bump micro SMD (Top View)

10131302

August 2002

© 2002 National Semiconductor Corporation

DS101313

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