Datasheet
LM136-2.5-N
SNVS749F –MAY 1998–REVISED APRIL 2013
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Typical Performance Characteristics (continued)
Temperature Drift
Figure 13.
APPLICATION HINTS
The LM136 series voltage references are much easier to use than ordinary zener diodes. Their low impedance
and wide operating current range simplify biasing in almost any circuit. Further, either the breakdown voltage or
the temperature coefficient can be adjusted to optimize circuit performance.
Figure 14 shows an LM136 with a 10k potentiometer for adjusting the reverse breakdown voltage. With the
addition of R1 the breakdown voltage can be adjusted without affecting the temperature coefficient of the device.
The adjustment range is usually sufficient to adjust for both the initial device tolerance and inaccuracies in buffer
circuitry.
If minimum temperature coefficient is desired, two diodes can be added in series with the adjustment
potentiometer as shown in Figure 15. When the device is adjusted to 2.490V the temperature coefficient is
minimized. Almost any silicon signal diode can be used for this purpose such as a 1N914, 1N4148 or a 1N457.
For proper temperature compensation the diodes should be in the same thermal environment as the LM136. It is
usually sufficient to mount the diodes near the LM136 on the printed circuit board. The absolute resistance of R1
is not critical and any value from 2k to 20k will work.
Figure 14. LM136 With Pot for Adjustment of Figure 15. Temperature Coefficient Adjustment
Breakdown Voltage
(Trim Range = ±70 mV typical)
(Trim Range = ±120 mV typical)
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