LM134 Series
Constant Current Source
and Temperature Sensor
FEATURES
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DESCRIPTIO
1µA to 10mA Operation
0.02%/V Regulation
0.8V to 40V Operating Voltage
Can be Used as Linear Temperature Sensor
Draws No Reverse Current
Supplied in Standard Transistor Packages
The LM134 is a three-terminal current source designed to
operate at current levels from 1µA to 10mA, as set by an
external resistor. The device operates as a true two-
terminal current source, requiring no extra power connec-
tions or input signals. Regulation is typically 0.02%/V and
terminal-to-terminal voltage can range from 800mV to
40V.
Because the operating current is
directly proportional to
absolute temperature
in degrees Kelvin, the device will
also find wide applications as a temperature sensor. The
temperature dependence of the operating current is
0.336%/°C at room temperature. For example, a device
operating at 298µA will have a temperature coefficient of
1µA/°C. The temperature dependence is extremely accu-
rate and repeatable. Devices specified as temperature
sensors in the 100µA to 1mA range are the LM134-3,
LM234-3 and the LM134-6, LM234-6, with the dash
numbers indicating
±3°C
and
±6°C
accuracies, respec-
tively.
If a zero temperature coefficient current source is re-
quired, this is easily achieved by adding a diode and a
resistor.
APPLICATIO S
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Current Mode Temperature Sensing
Constant Current Source for Shunt References
Cold Junction Compensation
Constant-Gain Bias for Bipolar Differential Stage
Micropower Bias Networks
Buffer for Photoconductive Cell
Current Limiter
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Remote Temperature Sensor with Voltage Output
500
Operating Current vs Temperature
225
V
IN
≥
5V
400
TEMPERATURE (°K)
V
+
R
R
SET
226Ω
10mV/°K
R1
10k
TA01a
300
LM234-3 V
–
200
100
0
0
100
300
400
200
OPERATING CURRENT (µA)
U
125
R
SET
= 226Ω
25
U
U
TEMPERATURE (°C)
–75
–175
–275
500
TA01b
1
LINER [ LINEAR TECHNOLOGY ]
