VDDA Regulator


I was a little surprised to see the 3.3V VDDA Regulator TPS73133 connected to VCC, which is also 3.3V out of the switching regulator.
TPS731xx is a very low dropout regulator, but it needs some dropout to give ripple rejection (Datasheet Figure 14).
I measured with DMM and scope, VDDA has even more noise than VCC.

I think VDDA regulator should be connected to VIN, at the cost of some dissipated energy. Perhaps a Si diode to lower the dropout.


Hi, actually this LDO was 3.0v but at some point we decided to replace it with 3.3v to support a wider range of sensors. We’re doing new prototypes and will consider replacing it with something else.

Yeah, that ended up like that because of the board rev time being long and we just needed to get the product out the door. Ibrahim, can you check on this with Kazhi if it makes sense to change?

Thank you for the great job you’ve done, keep it up!