TXB0104: Pull-up Supply & Resistor

Francis Jiang

Part Number: TXB0104
Other Parts Discussed in Thread: TXU0304, TXU0104, TXU0204

Tool/software:

Hi Team,

Customer feedback that the input voltage of B ports will influence by the outside pull-up resistor, under 3.3V pull-up supply:

With 10kohm resistor, the voltage of B ports is 1V
With 100kohm resistor, the voltage is ~0V
With 2kohm resistor, the voltage is right 3.3V

Based on #1, seems the internal impedance is ~4.348kohm, but it cannot meet the #3, could you please help check it and explain it to customer? Thanks.

BRs,

Francis

9 months ago

0 Clemens Ladisch 9 months ago

Guru 319890 points

TXB outputs have a drive strength of 20 µA. You should not use pull-up/-down resistors; see section 7.3.5 of the datasheet.

A unidirectional translator (TXU0104/TXU0204/TXU0304) would probably be a better solution.

0 Francis Jiang 9 months ago in reply to Clemens Ladisch

TI__Expert 3830 points

Hi Clemens,

Customer needs bi-directional translator and we found txs0104, customer and I would like to understand what's the differences here.

BRs,

Francis

0 Jack Guan 9 months ago in reply to Francis Jiang

TI__Mastermind 47391 points

Hi Francis,

The team is out today as today is a US Holiday. We will get back to you early next week. Thank you for understanding.

Regards,

Jack

0 Clemens Ladisch 9 months ago in reply to Francis Jiang

Guru 319890 points

What protocol are the signals using? Most protocols do not need an auto-bidirectional translator.

The TXS has integrated pull-up resistors and outputs open-drain signals.

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TXB0104: Pull-up Supply & Resistor