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TPS60400: Schottky diode

NAOKI AOYAMA
Guru 11215 points
Part Number: TPS60400

Hello,

Our customer use the TPS60400 to supply the minus voltage for Opamp.

It is mentioned " Integrated Active Schottky-Diode for Start-up Into Load" on the datasheet.

Does the Schottky diode operates during power-down?

The customer concern the minus supply voltage of the Opamp goes to above GND

at power-down.

Best Regards,

Naoki Aoyama

  • 0
    TI__Guru**** 150820 points
    Hi Aoyama-san,

    Yes, this is the typical application case as shown in Figure 21 of the D/S.

    Note that if the positive voltage is not present that the op amp will not be applying this voltage on the negative output.

    As well, the only way for the TPS6040x to power down is by its input voltage. So, the only time when TPS60400 is off is when there is no Vin and thus no voltage being applied through the op amp.
  • 0 in reply to Chris Glaser
    Guru 11215 points
    Hello Chris,

    Thank you for your reply.
    The customer use an op amp with dual supply.
    The TPS60400 supplies negative voltage and another device supplies positive voltage.
    In their system, the negative supply power down before the positive supply power down.
    So, the customer want to know the output impedance of the TPS60400 at power down.

    There is a Schottky diode on the output.
    Is it clamped at 0.4V?

    Regards,
    Naoki Aoyama
  • 0 in reply to NAOKI AOYAMA
    TI__Guru**** 150820 points
    Thanks for confirming.

    Without a Vin, the output of the TPS60400 looks like a silicon diode. Vout is clamped to a ~ +0.7V level.
  • 0 in reply to Chris Glaser
    Guru 11215 points
    Hello Chris,

    Thank you for your reply.

    Thanks,
    Naoki Aoyama