SN74LV14A: Not Schmitt trigger input.

Hi Clemens,

Thanks for the reply.
However, we are using the same circuit as Nexperia's product and Nexperia's product also has a hysteresis guarantee of 0.33V.
Why does this happen?

Best Regards,
Ryu.

Hi Ryu,

Could you please share the schematic? Are you seeing this result in multiple boards? Assuming proper usage of the device, it is not expected that the device would cause fluctuations like this on the input.

Best,

Ian

Hi Ian,

A schematic is attached.
We have also confirmed 90 similar symptoms.
When I re-mounted them in 74LV14APWJ, the symptoms disappeared and they do not oscillate.

Best Regards,
Ryu.

The input signal of U6A comes from a mechanical switch. This is not a triangle wave, bit the switch is not debounced; I suspect that the SN74LV14A is faster than the 74LV14A and passes through the bouncing. A capacitor from R9 to GND would help.

The schematic does not show the input signal of U6B.

The schematic does not show any decoupling capactior for U6.

Hi Clemens,

If it is a switch bounce, it would occur at other than intermediate potentials.

Please specify at which points in the schematic you have measured these waveforms.

Input/output pins.

1/2 or 3/4?

1/2.

Where does the triangle wave come from? A switch cannot generate it.

What is the actual problem that you have with the circuit shown in the schematic?