LM136-5.0QML, LM136A-5.0QML

SNVS352B – APRIL 2008 – REVISED MARCH 2013

www.ti.com

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 12 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 13. 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 12. LM136-5.0 with Pot for Adjustment of

Breakdown Voltage (Trim Range = ±1.0V Typical)

Figure 13. Temperature Coefficient Adjustment

(Trim Range = ±0.5V Typical)

8

Submit Documentation Feedback

Copyright © 2008–2013, Texas Instruments Incorporated

Product Folder Links: LM136-5.0QML LM136A-5.0QML