Problems with the Voltage Regulation Module VRM

[juchong]

Originally Posted by ozrien

Hey Juan,
I'd expect to be some ripple if you are drawing near the max continuous current (1.5A VRM User's Guide).

I didn't really understand this...

...so I grabbed my mecanum kit bot which uses a DAP1522(VRM1 - 20A fused) and M1011 Camera (powered from VRM2 - WAGO20A snapaction) and drove it around for a while. Ran a full battery down to the point where DS was in constant "Voltage Brownout" meanwhile watching the Axis Camera on the laptop running the DS. I didn't seem to lose camera or the router the entire time. Which seems like a good test of the power supply of the router and camera (each a VRM). Also ping times to the RIO seemed ok so I'm not sure this if the VRM has anything to due with your disconnects.

Plus Beta teams spent a lot of time beating up that aspect of the robot.

Can you explain the original problem a bit more?

Why would you guys label the maximum <peak> output current on the VRM instead of <continuous>? Seems a bit.. misleading? Why would you list peak current for one output (2A) and continuous (500mA) for the other? Very bad practice!

The original problem was that communication was dropping even though battery voltage did not fluctuate. Something as simple as enabling the robot would cause the DS to lose communication. I went through several steps to try and diagnose the issue (swapping radios, verifying connections, loading default code, etc.) and determined that the VRM was causing issues. We're continuing to use last year's regulators while we look into the issue with lab equipment.

Do you guys have any characterization data on these VRMs? Something a bit more concrete than anecdotal evidence? Also, why design the regulator's switching frequency to be in the audible range?

I'm about to head off to work and perform proper line/load regulation tests. I hope to post the results later today.