深圳市中立信电子科技有限公司

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 1 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 2. 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.