Hello: I'm using the OMAP 3503 and the TPS65950 on a Gumstix Overo Air module. The modules, and my baseboard, are working fine, stable, reliable. We have a TI MSP430 power controller that is powered on all the time, but controls +3.3V_Main to the Overo module.
Normally, everything works fine. But very rarely, on about 10% of our units, when +3.3V_Main is enabled, the PMIC does not enable core power to the OMAP, so the system does not boot.
VBAT to the Overo Air module (to the PMIC) is connected to the same +3.3V power that the MSP is powered by, and is on all the time. We are actually floating SYSEN and PWRON to the PMIC (is this ok?).
I can recover the system by killing VBAT on a lab bench, but this is unacceptable as an embedded system.
Can you please help brainstorm what might be going on here? I couldn't find any clues in the Gumstix forums, so I decided to check TI directly. Thanks very much.
Hi,
Please tell me what you mean by - We are actually floating SYSEN and PWRON to the PMIC (is this ok?).
Do you not connect anything to PWRON? Floating SYSEN output is ok.
PWRON should be connected to VBAT via a switch or via pull-up. It should not be left floating. You will surely have issues due to this.
Regards,
Gandhar.
I can't tell if SYSEN and PWRON are floating on the Gumstix module or not. I'm inquiring of the Gumstix people to confirm. Thank you very much for the pullup advice. I'll implement that. However, it takes a long time for the problem to appear so it will be a while before I know if it fixed anything! Thanks again. -- Ken
You can open a new post in case you have problems after trying the fix.
This pullup resistor to VBAT appears to have solved the problem. Thanks again.
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