LTC1261L Datasheet, PDF (1/12 Pages) Linear Technology – Switched Capacitor Regulated Voltage Inverter

LTC1261L
Switched Capacitor
Regulated Voltage Inverter
FEATURES
s _{Regulated Negative Voltage from a}
Single Positive Supply
s _{REG Pin Indicates Output is in Regulation}
s _{Adjustable or Fixed Output Voltages}
s _{Output Regulation: ±3.5%}
s _{Supply Current: 650µA Typ}
s _{Shutdown Mode Drops Supply Current to 5µA}
s _{Up to 20mA Output Current}
s _{Requires Only Three or Four External Capacitors}
s _{Available in MS8 and SO-8 Packages}
U
APPLICATIO S
s _{GaAs FET Bias Generators}
s _{Negative Supply Generators}
s _{Battery-Powered Systems}
s _{Single Supply Applications}
DESCRIPTIO
The LTC^®1261L is a switched-capacitor voltage inverter
designed to provide a regulated negative voltage from a
single positive supply. The LTC1261L operates from a
single 2.7V to 5.25V supply and provides an adjustable
output voltage from –1.23V to – 5V. The LTC1261L-4/
LTC1261L-4.5 needs a single 4.5V to 5.25V supply and
provides a fixed output voltage of – 4V to – 4.5V respec-
tively. Three external capacitors are required: a 0.1µF
flying capacitor and an input and output bypass capaci-
tors. An optional compensation capacitor at ADJ (COMP)
can be used to reduce the output voltage ripple.
Each version of the LTC1261L will supply up to 20mA
output current with guaranteed output regulation of ±3.5%.
The LTC1261L includes an open-drain REG output that
pulls low when the output is within 5% of the set value.
Quiescent current is typically 650µA when operating and
5µA in shutdown.
The LTC1261L is available in 8-pin MSOP and SO pack-
ages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
– 4V Generator with Power Valid
Waveforms for – 4V Generator with Power Valid
0V
5V
5V
1
V_CC
SHDN ⁸
10k
OUT
– 4V
C1
C2
2 _C1+
REG ⁷
1µF
0.1µF
3
LTC1261L-4
C1^–
OUT
6
4 _{GND COMP} 5
C3*
100pF
POWER VALID
V_OUT = –4V
C4 ^{AT 10mA}
+ 3.3µF
5V
SHDN
0V
5V
POWER VALID
0V
*OPTIONAL
1261L TA01
0.1ms/DIV
1261L TAO2
1