Hi.
We have a prototype board with a bunch of different power rails on it. One of them is a 1.8V rail and the supply for it is a TI TPS62743. Here's the schematic.
VBATT, top left, is from an 18650 lithium ion battery with a protection circuit. It's generally 2.8V to 4.1V. The load is a micro that, when we're testing, is in system off mode, drawing about 2 uA, and an accelerometer drawing about 15 uA.
We just made five prototype boards. On four of them, the current drawn by this part of the circuit, as measured at a jumper not shown on the schematic above but top left, near the battery, is about 25 uA. We're happy with that. That's what we expect.
One just one of these boards, the current is instead about 440 uA, which is way too high. We can't figure out why. We've put another jumper in just next to L201 and put it on the scope. It looks fine. Here's the scope screenshot. This is with the part in standby mode, presumably.
We've tested C201 and C202. They both look fine. We can't figure out where the current's going. Can anyone suggest anything?
Thanks.
