LM828 Switched Capacitor Voltage Converter
March 1999
LM828
Switched Capacitor Voltage Converter
General Description
The LM828 CMOS charge-pump voltage converter inverts a
positive voltage in the range of +1.8V to +5.5V to the corre-
sponding negative voltage of −1.8V to −5.5V. The LM828
uses two low cost capacitors to provide up to 25 mA of out-
put current.
The LM828 operates at 12 kHz switching frequency to re-
duce output resistance and voltage ripple. With an operating
current of only 40 µA (operating efficiency greater than 96%
with most loads), the LM828 provides ideal performance for
battery powered systems. The device is in a tiny SOT-23-5
package.
Features
n
n
n
n
Inverts Input Supply Voltage
SOT-23-5 Package
20Ω Typical Output Impedance
97% Typical Conversion Efficiency at 5 mA
Applications
n
n
n
n
n
n
Cellular Phones
Pagers
PDAs
Operational Amplifier Power Supplies
Interface Power Supplies
Handheld Instruments
Basic Application Circuits
Voltage Inverter
DS100137-1
+5V to −10V Converter
DS100137-2
© 1999 National Semiconductor Corporation
DS100137
www.national.com
NSC [ NATIONAL SEMICONDUCTOR ]
