TXS0108E-Q1: TXS0108EQPWRQ1

Roy Chan

Part Number: TXS0108E-Q1

Hi Expert:

our customer is design TXS0108EQPWRQ1 level shift from 1.8V SoC I2C bus to 3.3V device I2C bus . we found there have ~0.5V voltage DC level on both 1.8V and 3.3V I2C bus line , the ~0.5V voltage DC level will disappear when remove TXS0108EQPWRQ1, I attached customer design schematic (you can see page 1) and I2C CLK waveform( page 2) . I suspect the OE pin doesn't have pull down resistor causing the issue happened. could you please help review schematic and give comments about the schematic design ?

TXS0108EQPWRQ1 issues.pdf

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 244020 points

The TXS is a switch that connects both sides, so all four pull-up resistors act in parallel. The I²C devices must sink all that current, which results in a higher V_OL.

Pulling OE to GND would lower the DC level, but would also disconnect the I²C buses.

Remove the external pull-up resistors; the internal ones should be enough.

0 Roy Chan over 1 year ago in reply to Clemens Ladisch

TI__Intellectual 1865 points

Hi Clemens:

So you means we can remove all pull high resister using internal pull high is enough for both two side , right?

0 Clemens Ladisch over 1 year ago in reply to Roy Chan

Guru 244020 points

Yes.

0 Roy Chan over 1 year ago in reply to Clemens Ladisch

TI__Intellectual 1865 points

Hi Clemens:

Thank you very much your help. let us check again.

thank you

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TXS0108E-Q1: TXS0108EQPWRQ1