I have a customer who submitted the following question:
" I am trying the configure a TI UCD9081 power supply sequencer/monitor. I think I have the monitoring set up. What I am stuck on is getting the GPO pins to do anything. I am try to use then as Power On Resets. I want them all to be a logic lo while the power supplies are coming up. Once the power supplies are up and stable I want the GPO pin to transition to a logic hi. I can’t seem to get the GPO pins to do anything except sit at a logic lo. If someone could help me configure the GPO pin it would be appreciated."
What can we suggest to them?
Please send the customer configuration file (.PAR suffix).
Has your customer looked at the Advanced Sequencing and Monitoring Using the UCD9081 User's Guide regarding how to enable sequencing the GPOs either 1) do not, 2) after time, 3) after parent rail is in "regulation" and 3) after parent rail achieves a specified voltage? This is found on the UCD9081 Product Folder.
Responses from customer:
"Yes I did refer to the ‘Advance Sequencing and Monitoring Using the UDC9081’ manual. It isn’t really helping me. What I have discovered since I submitted my request is this:
If I have the programming pod connected to the my board it appears to work as I want. But, if I disconnect it does not behave as I want, the board stays in reset. I noticed that there is about 0.3V difference between Vcc when I have the programming pod plugged in (Vcc = 3.0V), and when the pod is disconnected (Vcc = 3.3V). My first thought that the difference in Vcc would mess up my monitoring criteria (UV/OV) and would always fail. So I re-configured the UCD9081 using the Internal reference of 2.5V. The exhibited the same behavior. It seemed to work with the pod plugged in, did not work with the pod disconnected."
Alex, the schematic is blank? Can you see anything or is my reader?
The customer circuit should not let Vcc drop to 3V without the POD. Have them work out the supply issue first and determine why it droops.
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