LM2660 Datasheet, PDF (1/12 Pages) National Semiconductor (TI) – Switched Capacitor Voltage Converter

September 1999
LM2660/LM2661
Switched Capacitor Voltage Converter
General Description
The LM2660/LM2661 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 LM2660/LM2661
uses two low cost capacitors to provide 100 mA of output
current without the cost, size, and EMI related to inductor
based converters. With an operating current of only 120 µA
and operating efficiency greater than 90% at most loads, the
LM2660/LM2661 provides ideal performance for battery
powered systems. The LM2660/LM2661 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 LM2660/LM2661 with an external clock. For
LM2660, a frequency control (FC) pin selects the oscillator
frequency of 10 kHz or 80 kHz. For LM2661, 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 0.5 µA. The oscillator frequency for the LM2661 is 80 kHz.
Features
n Inverts or doubles input supply voltage
n Narrow SO-8 and Mini SO-8 Package
n 6.5Ω typical output resistance
n 88% typical conversion efficiency at 100 mA
n (LM2660) selectable oscillator frequency: 10 kHz/80 kHz
n (LM2661) low current shutdown mode
Applications
n Laptop computers
n Cellular phones
n Medical instruments
n Operational amplifier power supplies
n Interface power supplies
n Handheld instruments
Basic Application Circuits
Voltage Inverter
Positive Voltage Doubler
DS012911-3
Splitting V_IN in Half
DS012911-4
© 1999 National Semiconductor Corporation DS012911
DS012911-26
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