LM2687 Datasheet, PDF (1/8 Pages) National Semiconductor (TI) – Low Noise Regulated Switched Capacitor Voltage

August 1999
LM2687
Low Noise Regulated Switched Capacitor Voltage
Inverter
General Description
The LM2687 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 LM2687 is ad-
justable between −1.5V and −5.2V. The LM2687 operates at
100 kHz (typical) switching frequency to reduce output resis-
tance and voltage ripple. With an operating current of only
500 µA (charge pump power efficiency greater than 90%
with most loads) and 0.05 µA typical shutdown current, the
LM2687 provides ideal performance for cellular phone power
amplifier bias and other low current, low noise negative volt-
age needs. The device comes in a small 8-pin MSOP pack-
age.
Features
n Inverts and regulates the input supply voltage
n Small MSOP-8 package
n 91% typical charge pump power efficiency at 10mA
n Low output ripple (1mV typical)
n Shutdown lowers Quiescent current to 0.05 µA (typical)
Applications
n Wireless Communication Systems
n Cellular Phone Power Amplifier Biasing
n Interface Power Supplies
n Handheld Instrumentation
n Laptop Computers and PDA’s
Typical Application Circuit
Connection Diagram
8-Pin MSOP
DS101180-1
DS101180-2
© 1999 National Semiconductor Corporation DS101180
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