LM2662/LM2663 Switched Capacitor Voltage Converter
January 1999
LM2662/LM2663
Switched Capacitor Voltage Converter
General Description
The LM2662/LM2663 CMOS charge-pump voltage con-
verter inverts a positive voltage in the range of 1.5V to 5.5V
to the corresponding negative voltage. The LM2662/LM2663
uses two low cost capacitors to provide 200 mA of output
current without the cost, size, and EMI related to inductor
based converters. With an operating current of only 300 µA
and operating efficiency greater than 90% at most loads, the
LM2662/LM2663 provides ideal performance for battery
powered systems. The LM2662/LM2663 may also be used
as a positive voltage doubler.
The oscillator frequency can be lowered by adding an exter-
nal capacitor to the OSC pin. Also, the OSC pin may be used
to drive the LM2662/LM2663 with an external clock. For
LM2662, a frequency control (FC) pin selects the oscillator
frequency of 20 kHz or 150 kHz. For LM2663, an external
shutdown (SD) pin replaces the FC pin. The SD pin can be
used to disable the device and reduce the quiescent current
to 10 µA. The oscillator frequency for LM2663 is 150 kHz.
Features
Inverts or doubles input supply voltage
Narrow SO-8 Package
3.5Ω typical output resistance
86% typical conversion efficiency at 200 mA
(LM2662) selectable oscillator
frequency: 20 kHz/150 kHz
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(LM2663) low current shutdown mode
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Applications
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Laptop computers
Cellular phones
Medical instruments
Operational amplifier power supplies
Interface power supplies
Handheld instruments
Basic Application Circuits
Voltage Inverter
Splitting V
IN
in Half
DS100003-1
Positive Voltage Doubler
DS100003-3
DS100003-2
© 1999 National Semiconductor Corporation
DS100003
www.national.com
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