LM3350

Switched Capacitor Voltage Converter

General Description

The LM3350 is a CMOS charge-pump voltage converter

which efficiently provides a 3.3V to 5V step-up, or 5V to 3.3V

step-down. The LM3350 uses four small, low cost capacitors

to provide the voltage conversion. It eliminates the cost, size

and radiated EMI related to inductor based circuits, or the

power loss of a linear regulator. Operating power conversion

efficiency greater than 90% provides ideal performance for

battery powered portable systems.

The architecture provides a fixed voltage conversion ratio of

3/2 or 2/3. Thus it can be used for other DC-DC conversions

as well.

Key Specifications

n 800 kHz switch frequency allows use of very small,

inexpensive capacitors.

n 4.2

Ω typical step-up output impedance

n 1.8

Ω typical step-down output impedance

n 90% typical power conversion efficiency at 50 mA

n 250 nA typical shutdown current

Features

n Conversion of 3.3V to 5V, or 5V to 3.3V

n Small Mini SO-8 package

n No inductor required

Applications

n Any mixed 5V and 3.3V system

n Laptop computers and PDAs

n Handheld instrumentation

n PCMCIA cards

Ordering Information

Order Number

Package Type

NSC Package

Drawing

Package

Marking

Supplied As

LM3350MMX

Mini SO-8

MUA08A

S00A

3500k Units on Tape and Reel

LM3350MM

Mini SO-8

MUA08A

S00A

1000 Units on Tape and Reel

Basic Operating Circuits

Connection Diagram

Step-Up Converter

DS100002-1

Step-Down Converter

DS100002-2

Mini SO8 Package

DS100002-3

Top View

December 1999

© 1999 National Semiconductor Corporation

DS100002

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