SN74HCS125: Input Voltages

Ray Vincent Aranzaso

Part Number: SN74HCS125

Hi,

Good Day. Where can I find VIH and VIL values in datasheet of SN74HCS125? If not found on the datasheet, can you help us to provide the value of VIH and VIL? Please advise. Thank you very much.

Best Regards,

Ray Vincent

over 2 years ago

0 Sebastian Muriel over 2 years ago

TI__Genius 14250 points

Hi Ray,

This device has Schmitt Trigger inputs so VIH = Vt+ max and VIL = Vt- min. Please see this appplication report for further details: Understanding Schmitt Triggers

Regards,

Sebastian

0 Ray Vincent Aranzaso over 2 years ago in reply to Sebastian Muriel

TI__Genius 14685 points

Hi Sebastian,

Good Day. Please see below the response of our customer to your query. Thank you very much.

So, I can interface a TTL logic device(74ABT125) which has Voh min as 2.5V@6V/3mA to the input of SN74HCS125D which has Vih=Vt+min as 2.1V @6V. Is my assumption is correct.

Best Regards,

Ray Vincent

0 Sebastian Muriel over 2 years ago in reply to Ray Vincent Aranzaso

TI__Genius 14250 points

That is correct as long as your Voh max is within the threshold.

Regards,

Sebastian

0 Ray Vincent Aranzaso over 2 years ago in reply to Sebastian Muriel

TI__Genius 14685 points

Hi Sebastian,

Good Day. Please see below the latest response of our customer to your reply. Thank you very much.

But in the app note (SCEA046) which you have shared states in page 2 waveform figure "the input levels Vih and Vil must be greater than (VT+ max) and less than (VT– min) to insure the part will switch." As per this app note (SCEA046) Vih should be greater than Vt+Max NOT Vt+Min. Which one is correct? app note (SCEA046) or your confirmation?

Best Regards,

Ray Vincent

0 Sebastian Muriel over 2 years ago in reply to Ray Vincent Aranzaso

TI__Genius 14250 points

Hi Ray,

The app note is correct, Vih should be greater than Vt+Max and Vil must be less than Vt-Min.

Regards,

Sebastian

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SN74HCS125: Input Voltages