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TDA4VH-Q1: VDD_IO_3V3 Power Switch max current rating

Peter Warnqvist37
Prodigy 190 points

Part Number: TDA4VH-Q1
Other Parts Discussed in Thread: TDA4VH, TPS22965

Hello TI!

On the EVM Board for TDA4VH-Q1 the Power Switches for VDD_IO_3V3 and VDD_GPIORET_IO_3V3, respectively (U75 and U62, TPS22965NDSGR) are each rated for 6A max. But the sum of the onboard loads on these two supplies seems to require far less than 6A. In our case, we don´t even have USB, PCIe, eMMC or any external loads so the current demand on those two supplies are even lower in our design. 
The Power Estimation Tool excel sheet does also not indicate any significant current demand by the TDA4VH itself on either of these two 3.3V supplies.

What is the reason for having such a high current rating on these two power switches on the EVM?

The answer would be input for us to see if we could step down in current rating on those two power switches in our design, or if there is something "hidden" that after all requires the switches to be able to handle as much as 6A, at least in peak situations?
Or is there perhaps some other switch property that is a consequence of an over-sized current rating, that is the actual property needed here?

  • 0
    TI__Guru 56835 points

    The power estimation tool is not great at estimating IO power.  Regardless - this number is usually fairly low.  It also only estimates processor IO power, it does not include any peripheral power.  Yes - very possible the TPS22965 is over-sized.  Recommendation is to determine current requirements for your system - and select size of regulator/load switch according to your needs.  This power rail is very dependent on customer's select peripherals - which may differ from TI's EVM.

  • 0 in reply to Robert Eschler
    Prodigy 190 points

    Hello Robert!

    Thanks for your input! Then my view on this is aligned with yours, i.e. that IO power of the processor is usually fairly low and the rest of the total current demand for the power supply in question comes from the peripherals in the same power domain which of course needs to be added separately when calculating the total current needed. As I mentioned, our design lacks many of the EVM parts powered by the supplies discussed here, e.g. the EVM Expansion slots that you of course need to allocate a pretty large supply current for.

    Thanks once more for your clarification!