This is a follow up to an earlier question I asked - I have an ATmega2560 running a number of sensors and servos. There are two separate SMPSs running off a single 12V battery, one generating 3.3V for the ATmega and the digital stuff, one generating 5V for the servos. When measuring current consumption at the battery (only place I can easily splice in), I see a baseline of about 3mA @ 12V until the servo kicks in, then consumption varies from about 50mA to as much as 200 (@ 12V). When the servo kicks in, I see something like this:
And then when it's shutting down, I see something like this before it stops:
Accompanied by a low rumbling noise coming from the servo, with it vibrating, but not moving.
The SMPS is a TI TPS562200, rated for 2A, with an inductor rated for 3.1A. I recorded the scope reading above running this from 8xAAA batteries in series. The servo has a 470uF electrolytic cap next to it.
Regulator circuit + layout:
Servo driver (I've played with different cap values from what's there)
Is the voltage drop at startup a concern, or normal servo behavior? Is the second waveform the servo trying to reach a position it can't get to? I'm starting to think that because the waveform seems to be fairly well-formed, which makes me think it's some sort of sampling/adjustment/seeking action going on.