Datasheet

LM136-5.0, LM236-5.0, LM336-5.0
www.ti.com SNVS750D –JUNE 1999–REVISED MARCH 2013
APPLICATION HINTS
The LM136-5.0 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 LM136-5.0 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, four diodes can be added in series with the adjustment
potentiometer as shown in Figure 15. When the device is adjusted to 5.00V 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 LM136-5.0.
It is usually sufficient to mount the diodes near the LM136-5.0 on the printed circuit board. The absolute
resistance of the network is not critical and any value from 2k to 20k will work. Because of the wide adjustment
range, fixed resistors should be connected in series with the pot to make pot setting less critical.
Figure 14. LM136-5.0 with Pot for Adjustment of Figure 15. Temperature Coefficient Adjustment
Breakdown Voltage (Trim Range = ±1.0V Typical) (Trim Range = ±0.5V Typical)
Typical Applications
* Adjust for 6.25V across R1
Figure 16. Precision Power Regulator with Low Temperature Coefficient
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Product Folder Links: LM136-5.0 LM236-5.0 LM336-5.0