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[ TPS65161 ] REF output for Other Device

Kenichiro
Mastermind 9165 points

[ TPS65161 ] REF output for Other Device

Hi,

My customer would like to use REF output as a reference voltage for other device. Other device has enough high impedance input and current draw would be around 50uA (<100uA). Can you recommend this? or does this cause any of unstable operation?

Thank you for your support in advance.
Regards,
Ken
  • 0
    TI__Guru 65300 points

    Hello Ken,

    The reference output of this part is as well used as the reference of the internal circuitry. If the external component changes the reference voltage on this pin or generates load transients, this could influence the part negatively.

    The feedback divider is already a load for this pin and it is recommended to have this resistor not lower than 40k. This means that we do not recommend a load of more than 30uA on this pin.

    An additional load of 50uA is possibly enough to reduce the reference voltage value and therefore I would not recommend adding such a load.

    You could use a resistor divider from e.g. the boost to generate such a reference voltage. (If the boost voltage is used, the ripple will be divided down as well.)

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Mastermind 9165 points

    Hi Brigitte,

    Thank you for your reply! I will consult with my customer and get back to you, if necessary.

    Keep in touch!

    Regards,
    Ken
  • 0 in reply to Kenichiro
    Mastermind 9165 points

    Hi Brigitte,

    Sorry for my reply being late. With regards to the discussion above, I have communicated with customer. In their current system, this REF pin is connected to OpAmp which has high-z input, i.e small bias current, so load should be smaller than 1uA. This should not be problem, correct?

    Thanks,
    Ken
  • 0 in reply to Kenichiro
    Mastermind 9165 points

    Hi Brigitte,

    Sorry for rushing you, but can you please help the discussion above for my customer?

    Thanks,
    Ken
  • 0 in reply to Kenichiro
    TI__Guru 65300 points

    Hello Ken,

    Please excuse the late response.

    1uA should not generate a problem.

    If your customer wants to be on the save side, I would recommend to increase the resistor from VREF to FBN to 42kohm if at the moment the minimum 40kohm is used.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Mastermind 9165 points

    Thank you for your support, Brigitte!!

    I will consult with my customer!

    Regards,
    Ken