LM3411 datasheet(11/13 Pages) NSC

11 / 13 page

Applications Information (Continued)

A simple 5V supply monitor circuit is shown in

Figure 12. Us-

ing the LM3411’s voltage reference, op-amp (as a compara-

tor) and output driver, this circuit provides a LED indication of

the presence of the 5V supply.

The LM3411 initial room temperature tolerance is ±1% and

±0.5% for the “A” grade part. If a tighter tolerance is needed,

a trim scheme is shown in

Figure 13 that provides approxi-

mately ±1% adjustment range of the regulation voltage

REG).

The LM3411 is guaranteed to drive a 15 mA load, but if more

current is needed, a NPN boost transistor can be added. The

circuit shown in

Figure 14 is a shunt regulator capable of pro-

viding excellent regulation over a very wide range of current.

Perhaps one of the simplest applications for the LM3411 is

the voltage detector circuit shown in

Figure 15 . The OUT pin

is low when the input voltage is less than V

REG. When the

V(IN) pin rises above V

REG, the OUT pin is pulled high by the

internal NPN output resistor.

Also an overvoltage detector, the crowbar circuit shown in

Figure 16 is normally located at the output of a power supply

to protect the load from an overvoltage condition should the

power supply fail with an input/output short.

DS011987-22

FIGURE 10. Precision Negative Voltage Regulator

DS011987-23

FIGURE 11. Precision Negative Voltage

Regulator with Accurate Current Limit

DS011987-24

FIGURE 12. 4.7V Power ON Detector with Hysteresis

DS011987-25

FIGURE 13. ±50 mV External Trim

DS011987-26

FIGURE 14. 250 mA Shunt Regulator

DS011987-27

FIGURE 15. Voltage Detector

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