TXS0108E: Access 485 signal after the interference is a big problem

Rhea Gao

Part Number: TXS0108E

Hi，

I used this chip to make the level of 3.3V to 1.8V. The first waveform was not connected, and the second waveform was wrong when TXS0108 was connected.

The pin SMA_IN2 is connected. The effect of external pull-up resistance test for 10K and 50K is the same. No, no improvement.

Please help to suggest the reason, thank you!

txs0108.docx

over 2 years ago

0 Michael Ikwuyum over 2 years ago

TI__Guru 52026 points

Hi Rhea,

With an external resistor added as either a pull-up or pull-down, a resistor divider network will be formed with the internal resistor of the device. If the value of the resistor is too small, the VOH or VOL will be impacted as observed. If the value is large, (i.e. >50kΩ), there will be very little change in the output voltage level. See [FAQ] How does a slow or floating input affect a CMOS device?

Please also see Effects of Pullup and Pulldown resistors on TXS and A Guide to Voltage Translation with TXS, thanks.

Best Regards,

Michael.

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TXS0108E: Access 485 signal after the interference is a big problem