LM393B: negative 12V usage

Ann_Lien

Part Number: LM393B
Other Parts Discussed in Thread: LM393

Hello expert,

Customer would like to use LM393B to compare -12V voltage. May I know if we need to apply V+=0V and V- = -12V to meet Vcm requirement in datasheet page 6? Thanks a lot!!

Best regards,

Ann Lien

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Ann,

yes, this is one method. The GND pin of LM393B should be <= -12V then.

Another method is the potential shifter which uses a pull-up and pushs up the input signal by the help of a voltage divider. A simple example is shown below:

ann_lm393.TSC

The advantage: The LM393 needs no longer to be powered by a negative supply voltage with the shifter. Of course, you must never violate the absolute maximum ratings referring to the input voltage. So, eventually, an additional protection circuit might be needed:

ann_lm393_1.TSC

Kai

0 Chuck Sins over 5 years ago in reply to kai klaas69

TI__Mastermind 26690 points

thanks Kai

Excellent suggestions

Chuck

Amplifiers

Amplifiers forum

LM393B: negative 12V usage