LTC1261
14
1261fb
For more information www.linear.com/LTC1261
TYPICAL APPLICATIONS
This circuit uses the LTC1261CS8 to generate a –1.24V
output at 20mA. Attached to this output is a 312Ω resistor
to make the current/voltage conversion. 4mA through 312Ω
generates 1.24V, giving a net 0V output. 20mA through
312Ω gives 6.24V across the resistor, giving a net 5V
output. If the 4mA to 20mA source requires an operat-
ing voltage greater than 8V, it should be
powered from a
separate supply; the LTC1261 can then be powered from
any convenient supply, 3V ≤ V
S
≤ 8V. The Schottky diode
prevents the external voltage from damaging the LTC1261
in shutdown or under fault conditions. The LTC1261’s
reference is trimmed to 3.5% and the resistor adds 1%
uncertainty, giving 4.5% total output error.
6
5
2
3
LTC1261
OUT
ADJ
C1
+
C1
–
LTC1261 • TA11
1
8V
3.3µF
312Ω
1%
0.1µF
1N5817
4mA
TO 20mA
SENSOR
OPTIONAL
INPUT
PROTECTION
DIODES
–1.24V
4
1µF
0V TO 5V
±5%
V
CC
GND
+
–
+
–1.24V Generator for 4mA-20mA to 0V-5V Conversion
