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1V Power Rail Question

Former Member

I was looking at the 1.0V power section on the microzed (U17 and surrounding parts).

When the microzeds are in the Breakout Carrier and powered up, I am only seeing 0.2 Volts across C57. This is true for all my microzeds.

Shouldn't this supply be 1 Volt?

Cheers,
David

-EDIT-
1 of my 4 microzeds does in fact show 1.0V for this node.

Any ideas why the others do not?

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  • 0

    Hi David.  Do you also see 0.2V if you do NOT have it plugged into the breakout carrier?  Is there a bit stream loaded in the FPGA?

    Do you have an oscilloscope you could put on the 1V during startup to see if it is coming up and turning off or if it isn't coming up at all?

    I haven't seen this before.  It could be a result of the input supply having insufficient power.  If the input supply is limiting, it could cause various rails to not start.  Are there any heavy loads on the carrier?  Are you trying to power it off a USB port?  If so, try powering it off a DC source or off say a USB cell phone charger.

    Thanks

    Chris

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  • 0

    Hi David.  Do you also see 0.2V if you do NOT have it plugged into the breakout carrier?  Is there a bit stream loaded in the FPGA?

    Do you have an oscilloscope you could put on the 1V during startup to see if it is coming up and turning off or if it isn't coming up at all?

    I haven't seen this before.  It could be a result of the input supply having insufficient power.  If the input supply is limiting, it could cause various rails to not start.  Are there any heavy loads on the carrier?  Are you trying to power it off a USB port?  If so, try powering it off a DC source or off say a USB cell phone charger.

    Thanks

    Chris

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  • 0 in reply to ctammann

    Hi Chris,
    Good ideas.

    I've been running off an AC adapter rated at 2 Amps, not a USB port. I swapped it out for another 2A rated adapter and still see the same behavior.

    I removed the uZed from the carrier and powered it from the AC adapter. Now, none of the regulators are producing outputs, rather than half of them (see my other post). This is what I would expect, since they are enabled in series.

    I monitored the 1V power bus with a scope. Upon applying power, the voltage increases from 0V to 0.2V in about 200 microseconds and stays steady at 0.2V.

    Cheers,
    David