Programmable Power Suppy 'bug'?

Support & Troubleshooting Moku:Go
1

All,
I am using a Moku:Go with programmable power supplies:
‘firmware’: 591,
‘hardware’: ‘Moku:Go’,
‘version’: ‘3.2’
When I use PPS ID 3 or 4 to drive a load. it sometimes doesn’t ‘turn on’ until I unplug and replug the load or reboot the device. This is very often following a disable/enable cycle.
This is very awkward for remote operation. Is this a known bug? Is there a workaround?
Thank you for you assistance.

2

Hi @brucat

I’m sorry, this is a known issue but we do not have a workaround for you at the moment. I’ll update our bug report with the information you’ve provided and will loop you in again when this is fixed or if anything changes.

Thanks for your patience,
Indira

3

Hello,
I have the same issue myself, except plugging/unplugging “almost never” fixes the problem (say, one time out of 10).
While it is nice to learn that this is a “known issue”, I am much less happy about having paid extra money for two non-operational power supplies.
I would love to know what are the causes of this erratic behavior of the power supplies, and if there are any updates to the situation.
Best regards,
JJ

4

Hi @JeromeJuillard,

What you’re experiencing seems to be a different issue if turning the power on, then applying the load does not work for you. The PPSU can sometimes latch up if you turn it on under load, this is part of the hardware in the overcurrent protection circuit. To avoid this, first turn on the PPSU, then connect the load.

If this does not resolve the issue then I think you may be seeing something else, are you able to tell me more about your issue? What loads you are applying, how are you setting the power supplies, how are you powering your Moku:Go, etc.

Thanks,
Indira

5

Hello Indira, thank you for your reply:

  • turning on PPSU3 or 4 before connecting to the load is precisely what I am doing, and it (almost) never works.
  • the issue is not specific to my circuit : when I use the Moku’s own oscilloscope to measure the voltage at PPSU3/4 output, with no load attached, I can see the voltage is not the prescribed 5V.
  • for completeness, in my circuit: I use PPSU1 to generate a -5V voltage rail, PPSU2 to generate 16V for biassing a MEMS resonator (no power consumption), and PPSU3 or 4 for the +5V voltage rail. The active load is one opamp and one comparator, requiring at the very most 10mA.
  • I have found the following fix works: switch on PPSU3/4 at the minimum voltage setting (700mV) and then change the setting to 5V. This works whether I am connected to the load or not.
  • still it does not explain why PPSU3 and 4 are faulty and why none of this is mentioned in the specifications.
    Best regards
    JJ
6

I can confirm the behavior described by JJ with all 7 of my Mokus. It is clearly an undocumented bug.