Other Parts Discussed in Thread: LP-AM243
I am going through the power supply circuits on the LP-AM243x board and trying to understand them. Most of it is straightforward, but I found something I don't understand.
The net "VDDSHV_SDIO" does not appear to have a voltage source.
Searching on the PDF, it connects to:
- Decoupling caps C160, C172
- Pin J17 (CAP_VDDSHV_MMC1) and its capacitor C143
- Pull up resistors on the MMC1 connection to BP header (all not fitted: R194, R192, R19, R193, R21)
- Pins L16, L17 VDDSHV5 (which is a power input)
Measuring at R192/R193/R194 there is +3.3V on the pads - so it is connected somehow.
Is it leaking out through a pin and inadvertently powering this rail? Or is it connecting somehow that's not shown in the PDF?
So I also had a look at the AM64x EVM circuit and found a similar thing - here the net VDDSHV_SD_IO apparently has no source.
What am I missing here?
Thanks
Andy
