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TPS386000-Q1: Inquiry about pull-up setting for MR pin

MJ Jeon
Genius 5240 points
Part Number: TPS386000-Q1
Other Parts Discussed in Thread: TPS386000

Hi, TI Support Team

A customer company is using the TPS386000-Q1 to review the circuit.

The master (TPS386000-Q1) is controlling the MR pins of up to 5 slaves (TPS386000-Q1) through Reset out.

At this time, 3.3V pull-up is applied to the slave's MR pin, but it has been reported that the level drops to 1.6~2.4V.

In this case, if the pull-up resistor connected to the MR pin on the slave side is removed, it is said to operate normally.

Question.

Is there any problem in operation if I remove the pull-up resistor connected to the MR pin?

(The datasheet is linked.)

What is the expected cause of the level drop in the condition in question?

For reference, the circuit diagram is attached.

Thanks.

Regards,

MJ

  • +1
    TI__Mastermind 28505 points

    Hi MJ,

    Correct me if I am wrong but the customer has the output of one TPS386000-Q1 controlling 5 /MR pins of TPS386000-Q1. Is that correct?

    From the schematic, what is pulling up the /RESET pins?  Is it from the /MR's pullup resistors on each of the TPS386000-Q1?  What is the value of the pullup resistor on the /MR pins?  If the master TPS386000-Q1 is pulling down on the /MR pins of 5 slave TPS386000-Q1 where each slave of TPS386000 has a 10K pullup resistor, the effective resistance is 2Kohms which violates the safe operation of the output transistor.  See below:

    Thanks,

    Ben

  • 0 in reply to Ben C
    TI__Mastermind 28505 points

    Hi MJ,

    Are there any updates on this issue?

    Ben