LM231, LM331

SNOSBI2C – JUNE 1999 – REVISED SEPTEMBER 2015

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8.3 Feature Description

The LMx31 operate over a wide voltage range of 4 V to 40 V.

The voltage at pin 2 is regulated at 1.90 VDC for all values of i between 10 μA to 500 μA. It can be used as a

voltage reference for other components, but take care to ensure that current is not taken from it which could

reduce the accuracy of the converter.

8.4 Device Functional Modes

The output driver transistor acts to saturate pin 3 with an ON resistance of about 50

Ω. In case of overvoltage,

the output current is actively limited to less than 50 mA.

If the voltage on pin 7 is higher than pin 6 when pin 5 crosses

⅔ VCC, the LMx31 internal flip-flop will not be

reset, and the current at pin 1 will continue to flow, trying to make the voltage at pin 6 higher than pin 7. This

condition will usually apply under start-up conditions or in the case of an overload voltage at signal input. During

this sort of overload the output frequency will be 0. As soon as the signal is restored to the working range, the

output frequency will be resumed.

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