LM2903V: false trigger when input is sine waveform

Haiwen Huang

Part Number: LM2903V
Other Parts Discussed in Thread: LM2903, LM339

Dears:

Customer found false trigger when input is sine waveform.

CH1 yellow is sine waveform

CH2 blue is ref voltage 2.66V

CH3 red is LM2903V output.

You can see LM2903V triggered before sine voltage reach ref voltage. Could you please help advise how to solve this issue ?

0 Paul Grohe over 2 years ago

Hello Haiwen,

Can you please supply a schematic, and the comparator supply voltage.

If the supply voltage is 3.3V, then most likely the input voltage range is being violated.

The maximum input voltage for the LM2903 is VCC-2V.

So the maximum input voltage is 2V below the VCC supply, or 1.3V max for a 3.3V supply.

Output inversion is one sign of violating the input range.

Please see the LM339 family application note, section 3.4:

0 HO SIU over 2 years ago

Hey Haiwen,

It's been a while since we've heard from you. Feel free to open up this post again if you have any further questions.

Thanks,

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