PCM1808-Q1: schmitt trigger input

Shinji Tsuji

Genius 12338 points

Part Number: PCM1808-Q1

Hi team,

Could you please advise how much hysteresis does the logic input pins have?

regards,

over 2 years ago

0 Arthur Brown over 2 years ago

TI__Genius 16870 points

Hi,

Let me look into this and see if we have any documentation

Regards,
Arthur

0 Arthur Brown over 2 years ago

TI__Genius 16870 points

Hi Shinji,

why do you ask? From the datasheet a logic high is 2V and logic low is 0.8V. I would assume that the hysteresis is 1.2 V, or rather the Schmitt trigger latches "high" at 2V and "low" at 0.8V

Regards,

Arthur

0 Shinji Tsuji over 2 years ago in reply to Arthur Brown

TI__Genius 12338 points

Hi Arthur,

Thank you. Let me double check.

Once logic is latched High(Low), it will not turn Low(High) until 0.8V(2.0V).

It means there is no input condition to make logic unstable, correct?

regards,

+1 Arthur Brown over 2 years ago in reply to Shinji Tsuji

TI__Genius 16870 points

Hi Shinji,

I did a bit more searching around E2E, and I think that this part is not actually a Schmitt trigger input, because if it was then in the electrical characteristics section of the D/S there would be a V_t+ and V_t- spec given.

https://e2e.ti.com/support/logic-group/logic/f/logic-forum/501754/schmitt-triggers-on-sn74ahc1g00-inputs

https://e2e.ti.com/support/logic-group/logic/f/logic-forum/561675/sn74lvc1g07-schmitt-trigger-input-on-sn74lvc1g06-but-not-sn74lvc1g07

Unfortunately, I can not provide a number for the hysteresis on the input pins. if the signal is specially slow or noisey it may be best yo use and external true Schmitt trigger.

Regards,

Arthur

Audio

Audio forum

PCM1808-Q1: schmitt trigger input