Other Parts Discussed in Thread: LM2903, LM393
My customer has encountered output issue when replacing LM2903 with LM2903B. There is no any other change besides the comparator bom change.
Please see the normal waveforms (LM2903) and abnormal waveforms (LM2903B) as below,
Channel 1: input signal of pin5; Channel 2: input signal of pin6 (2.5V reference voltage); Channel 3: output signal of channel 7.
The supply voltage for the comparator is 5V while the pull-up resistance is 4.7kohm.
The first figure works well but in the second figure, LM2903B's output has abnormally flipped even though the channel one voltage hasn't override the reference voltage.
This is mature design in my customer side and this phenomenon works only with LM2903B. On the same board, once the device is changed to LM2903 again, this issue will be solved.
Please help give advise. Thanks!