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TPS74201 Reverse Current Protection

Roy Rodgers
Prodigy 20 points
Other Parts Discussed in Thread: TPS74201, PTH08T230W

Using Vin - 2.5V, the output is adjustable between 1.0V, and 1.8V - it is possible that another supply is feeding the same rail at a higher voltage.

Question - What is the expected behavior when I apply a 1.8V voltage to the output, if the regulator is biased for an output voltage of 1.0V.

  • 0
    TI__Expert 3540 points

    Hi Roy,

    Yes, you can have another supply feeding the same rail at a higher voltage, applying a higher voltage to the output of TPS74201 than it is set to deliver will just put the device in an unregulated state where the current will not flow from output to input. This is because like most LDOs, TPS74201 does not sink current meaning there won't be any significant reverse current (this will be true as long as the V_OUT is less than V_IN).

    Also, I noticed you seem to be using R1409 to adjust your LDO's output between 1.0V and 1.8V by pulling DCA0_80_VCCO_SET to 0.8V or Ground, this is the case, right?

    We actually mention an application that takes advantage of this feature in one of our blogs, feel free to check it out:
    "How-to Improve Buck Converter Light Load Efficiency with an LDO" Part 1 / Part 2

    Best Regards,
    Victor

  • 0 in reply to Victor Salomon
    Prodigy 20 points

    Thank you, that is what I suspected - but had the LDO pull a lot of current for some reason.

    Turns out the customer had a PTH08T230W connected to the same rail, that was also enabled - the switcher was trying to regulate and pulling the rail down!

    Disabling the switcher, fixed the problem.