LTC1261L_15 Datasheet, PDF (1/14 Pages) Linear Technology – Switched Capacitor Regulated Voltage Inverter

FEATURES
n _{Regulated Negative Voltage from a}
Single Positive Supply
n _{REG Pin Indicates Output is in Regulation}
n _{Adjustable or Fixed Output Voltages}
n _{Output Regulation: ±4.5%}
n _{Supply Current: 650µA Typ}
n _{Shutdown Mode Drops Supply Current to 5µA}
n _{Up to 20mA Output Current}
n _{Requires Only Three or Four External Capacitors}
n _{Available in MS8 and SO-8 Packages}
APPLICATIONS
n _{GaAs FET Bias Generators}
n _{Negative Supply Generators}
n _{Battery-Powered Systems}
n _{Single Supply Applications}
LTC1261L
Switched Capacitor
Regulated Voltage Inverter
DESCRIPTION
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 capacitors. 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 ±4.5%.
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 packages.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
–4V Generator with Power Valid
5V
5V
1 _VCC
SHDN ⁸
10k
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
*OPTIONAL
1261L TA01
Waveforms for –4V Generator with Power Valid
0V
OUT
–4V
5V
SHDN
0V
5V
POWER VALID
0V
0.1ms/DIV
1261L TA02
1261lfa
1