UCD3138: Questions of UCD3138 Pmbus pull up resistor

HAN LEE

Part Number: UCD3138

Hi all,

Does TI have recommend pull-up resistor value for pmbus-data/pmbus-clock pin?

We encounter FW download fail if we put 10k to pull up, I'd like to double confirm if I follow open loop board put 1.5k to pull up , the FW download can be solved.

May I know what's the side effect if I put a higher resistor to pull up,thanks.

over 6 years ago

0 Yitzhak Bolurian over 6 years ago

TI__Mastermind 18370 points

The pull-up resistor value depends on the number of slaves connected to the bus, the Bus capacitance and the speed of communication.
Therefore there is no one single recommended value of pull-up resistors.
I would recommend a value of 750 Ohms or 1 KOhms for the speed of 400 bps.
If you reduce the Bus capacitance to minimum and reduce the speed to 100 KHz, then you may be able to work with higher values of pull-up.

0 HAN LEE over 6 years ago in reply to Yitzhak Bolurian

Expert 1515 points

Hi Yitzhak,

Thanks, I got it.

0 Yitzhak Bolurian over 6 years ago in reply to HAN LEE

TI__Mastermind 18370 points

Welcome. Please be so kind as to set the status of this post to resolved.

Regards,

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UCD3138: Questions of UCD3138 Pmbus pull up resistor