LM3351 Datasheet, PDF (1/8 Pages) National Semiconductor (TI) – Switched Capacitor Voltage Converter

December 1999
LM3351
Switched Capacitor Voltage Converter
General Description
The LM3351 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 LM3351 is pin for pin compatible with the
LM3350 but consumes 66% less quiescent current. The
LM3351 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 200 kHz switch frequency allows use of very small,
inexpensive capacitors.
n 4.2Ω typical step-up output impedance
n 1.8Ω typical step-down output impedance
n 95% typical power conversion efficiency at 50 mA
n 250 nA typical shutdown current
n Low quiescent current extends battary life
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
LM3351MMX
LM3351MM
Mini SO-8
Mini SO-8
Basic Operating Circuits
NSC Package
Drawing
MUA08A
MUA08A
Step-Up Converter
Package
Marking
S05A
S05A
Supplied As
3500 Units on Tape and Reel
1000 Units on Tape and Reel
Step-Down Converter
Connection Diagram
DS100146-1
Mini SO8 Package
© 1999 National Semiconductor Corporation DS100146
DS100146-3
Top View
DS100146-2
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