Power Supplies are not adjustable

[Dat Nguyen]

I have had Discovery 3. Two power supplies are not adjustable. It is about 5 volt, not matter what I have to try to change. Do anyone know why?

[attila]

Hi @Dat Nguyen

Do you have anything connected to the V+ output ? Can you tell me what you used it for last time?

The device USB power/current is very low, it should be at least about 3W/600mA, and the USB voltage is too low.
The lack of USB power, essentially dropping supply voltage could cause device malfunction.

Try using other USB port, computer, powered hub, 5V DC auxiliary power supply.
The latest software version overcomes a problem caused by low voltage, but the real solution is to provide sufficient power for the device.

 

[Dat Nguyen]

I have a DUT that needs 1.25 Volt. I am using AD2 and it works fine. AD2 is going to be absolute, so I am trying to use AD3. When I plug it in, it is always about 5Volts, no matter what I have to adjust. My DUT uses only about 15 mA and 1.35 Volt. 

[Dat Nguyen]

I have swap to different USB hub, it works fine. Now I can adjust voltage for supplies.

[attila]

Hi @Dat Nguyen

I managed to reproduce the issue, using USB cable + unpowered hub + extension cable + another cable. The analog circuitry is reset or not turning on due to low USB voltage.
The next software version will report such problem.

[attila]

Hi @Dat Nguyen