LM2621 Low Input Voltage, Step-Up DC-DC Converter
February 2000
LM2621
Low Input Voltage, Step-Up DC-DC Converter
General Description
The LM2621 is a high efficiency, step-up DC-DC switching
regulator for battery-powered and low input voltage systems.
It accepts an input voltage between 1.2V and 14V and con-
verts it into a regulated output voltage. The output voltage
can be adjusted between 1.24V and 14V. It has an internal
0.17Ω N-Channel MOSFET power switch. Efficiencies up to
90% are achievable using the LM2621.
The high switching frequency (adjustable up to 2MHz) of the
LM2621 allows for tiny surface mount inductors and capaci-
tors. Because of the unique constant-duty-cycle gated oscil-
lator topology very high efficiencies are realized over a wide
load range. The supply current is reduced to 80µA because
of the BiCMOS process technology. In the shutdown mode,
the supply current is less than 2.5µA.
The LM2621 is available in a Mini-SO-8 package. This pack-
age uses half the board area of a standard 8-pin SO and has
a height of just 1.09 mm.
Features
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Small Mini-SO8 Package (Half the Footprint of Standard
8-Pin SO Package)
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1.09 mm Package Height
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Up to 2 MHz Switching Frequency
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1.2V to 14V Input Voltage
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1.24V - 14V Adjustable Output Voltage
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Up to 1A Load Current
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0.17
Ω
Internal MOSFET
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Up to 90% Regulator Efficiency
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80 µA Typical Operating Current
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<
2.5µA Guaranteed Supply Current In Shutdown
Applications
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PDAs, Cellular Phones
2-Cell and 3-Cell Battery-Operated Equipment
PCMCIA Cards, Memory Cards
Flash Memory Programming
TFT/LCD Applications
3.3V to 5.0V Conversion
GPS Devices
Two-Way Pagers
Palmtop Computers
Hand-Held Instruments
Typical Application Circuit
DS100934-12
© 2000 National Semiconductor Corporation
DS100934
www.national.com
NSC [ NATIONAL SEMICONDUCTOR ]
