TXU0104: Use with quadrature encoder PWM signals at 5V HIGH

Christopher Buckley

Part Number: TXU0104
Other Parts Discussed in Thread: SN74AHC125

I've run into issues choosing the wrong translators in the past, so just wanted someone to confirm that the TXU0104 is an appropriate choice for this where I've got two quadrature encoders (4x signals) running from 0 to 5V and I need them translated down to 3V3 for the MCU GPIO pins.

Best regards,
Christopher

over 3 years ago

+1 Clemens Ladisch over 3 years ago

Guru 318050 points

Yes, the TXU will work for this.

For unidirectional downtranslation, you could also use any buffer with overvoltage-tolerant inputs, e.g., SN74AHC125.

0 Christopher Buckley over 3 years ago in reply to Clemens Ladisch

Intellectual 330 points

Thank you Clemens. Out of curiosity, is there any reason you recommend the SN74AHC125 in particular (over the TXU)?

0 Clemens Ladisch over 3 years ago in reply to Christopher Buckley

Guru 318050 points

It's cheaper.

0 Christopher Buckley over 3 years ago in reply to Clemens Ladisch

Intellectual 330 points

Thanks Clemens. I had a skim through both datasheets and left a fair bit confused. Are you sure you meant the SN74AHC125? It doesn't even look like this does any level shifting? It looks like just a 4 channel buffer. Can you elaborate on how this would be used for voltage level shifting?

0 Clemens Ladisch over 3 years ago in reply to Christopher Buckley

Guru 318050 points

The SN74AHC125 accepts 5 V at its inputs even when its own power supply is 3.3 V.

0 Christopher Buckley over 3 years ago in reply to Clemens Ladisch

Intellectual 330 points

Thank you for the quick reply. After rereading your initial response, that makes more sense. Thanks again!

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TXU0104: Use with quadrature encoder PWM signals at 5V HIGH