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TPS63031 manual Pass-Through Function during Shutdown

Tobias Rohde
Prodigy 150 points
Other Parts Discussed in Thread: TPS63031

Hello,

i want to use the TPS63031 3V3 (fixed output) Buck/Boost Converter.

In my system there are a 5V (USB) and a 2V...3V input supply (2xNiMH) voltages. The TPS63031 is controlled by a MCU which can run from 2V...3.6V. In some cases the MCU needs regulated 3.3V and therefore enables the Converter but in other cases (e.g. low power modes or startup) it wants to be sourced directly by the 2V...3V battery without using (EN=pulled Low) the TPS63031. So what i need is a input pass-through. "Unfortunately" the TPS63031 does a "Load Disconnect During Shutdown".

I ask myself if one of the attached manual pass-through solutions (see picture) could work in this case.

Thanks for any help!

  • 0
    TI__Expert 7110 points

    Let me add my thoughts on your circuits:


    Basically speaking i think bypassing the device will work. From an device perspective, the output is pre-biased when you turn it on. This an operation scenario the device can handle.

    Your first circuit does exactly this. I guess you added the diode in the output path in your 2nd circuit to prevent negative current into the device. This will cause a drop in the programmed voltage and will not be necessary, as the device disconnects the output internally.
    Your third circuit should help you to reduce the drop when bypassing, but it is harder to judge what will happen as two devices (PMOS & DC/DC) react simultaneously.

    Of course it is absolutely necessary to check the circuit! You can use an EVM and quickly modify to above's circuits.

  • 0 in reply to Florian Feckl
    Prodigy 150 points

    Thank you! Danke!