TXB0108: The output level of low signal issue

Kai Lai

Part Number: TXB0108
Other Parts Discussed in Thread: TXS0108E

Hi Team,

My customer is designing TXB0108, the schematic as below.

PCIE_CLKREQ_N is an open drain at A side, and customer want to set it low from A side.

However the min voltage at B side always around 0.5V (customer need lower than 0.45V) even they pull down to GND.

Is this a normally scenario? Or how can customer modify it so that B side can output lower 0.4V?

Thanks !

Kai

0 Clemens Ladisch over 2 years ago

Guru 243980 points

The test condition is 20 µA. The TXB has extremely weak outputs and does not work with PCI signals. (See section 8.3 of the datasheet.)

It might be possible to use the TXS0108E (which has internal pull-ups on all I/Os).

0 Kai Lai over 2 years ago in reply to Clemens Ladisch

Hi Clemens,

Thanks for your reply,

Does we have any pin to pin device can be suggest? (feature internal pull-ups on all I/Os like your suggest.)

Kai

0 Wang Li Cheng over 2 years ago in reply to Clemens Ladisch

Hi Clemens,

Thanks for your reply.

After checking for TXS0108E.

What's "one shot" meaning in the datasheet to us?

And we want to know, does external pull-up resistor still effect the output VOL levels as TXB?

Will it still have a weak outputs and may over than 0.4V?

Best regards,

Licheng

0 Dylan Hubbard over 2 years ago in reply to Wang Li Cheng

Hi Li,

The two app notes below will provide more details on how TXS works as well as how pull-ups impact the VOL.

Logic forum