
LM2685
Dual Output Regulated Switched Capacitor Voltage
Converter
General Description
The LM2685 CMOS charge-pump voltage converter oper-
ates as an input voltage doubler, +5V regulator and inverter
for an input voltage in the range of +2.85V to +6.5V. Five low
cost capacitors are used in this circuit to provide up to 50mA
of output current at +5V (± 5%), and 15mA at 5V. The
LM2685 operates at a 130 kHz switching frequency to re-
duce output resistance and voltage ripple. With an operating
current of only 800A (operating efficiency greater than 80%
with most loads) and 6A typical shutdown current, the
LM2685 is ideal for use in battery powered systems. The
device is in a small 14-pin TSSOP package.
Features
n
+5V regulated output
n
Inverts V
05(+5V) to VNEG(5V)
n
Doubles input supply voltage
n
TSSOP-14 package
n
80% typical conversion efficiency at 25mA
n
Input voltage range of 2.85V to 6.5V
n
Independent shutdown control pins
Applications
n
Cellular phones
n
Pagers
n
PDAs
n
Handheld instrumentation
n
3.3V to 5V voltage conversion applications
Typical Application and Connection Diagram
10110001
10110002
14-Pin TSSOP
Ordering Information
Order Number
Package Type
NSC Package
Drawing
Supplied As
LM2685MTC
TSSOP-14
MTC14
94 Units, Rail
LM2685MTCX
TSSOP-14
MTC14
2.5k Units, Tape and Reel
May 2000
LM2685
Dual
Output
Regulated
Switched
Capacitor
V
oltage
Converter
2004 National Semiconductor Corporation
DS101100
www.national.com