UCD9090 Fault Response

Oliver Mcconnell

Other Parts Discussed in Thread: UCD9090

I am using a UCD9090 and can verify that when a voltage drops below my under voltage threshold it gives an UV_FAULT and turns off the rail and its slaves. A problem I have is that there is a board we have that has a bad rail that never starts up so clearly it is below the threshold, but the rail never gives an UV_FAULT so it doesn't shut anything else off and the boards reports that everything is good. How do I fix this?

over 7 years ago

0 Zhiyuan Hu over 7 years ago

TI__Genius 9845 points

If a rail voltage never rises above PowerGoodOn threshold, the device will not trigger UV fault because this can be the case in soft start.

You can configure Ton_Max fault. After EN pin is asserted, if the rail voltage doesn't rise above PowerGoodOn, Ton_max fault will be reported. It can shut down this and slave rails.

0 Oliver Mcconnell over 7 years ago in reply to Zhiyuan Hu

Prodigy 120 points

TON_MAX fault is greyed out in the GUI and cannot be enabled. It says (Not available for TON_MAX fault)

0 Zhiyuan Hu over 7 years ago in reply to Oliver Mcconnell

TI__Genius 9845 points

It shouldn't be. There is a No Limit checkbox under Max Turn On. Uncheck the No Limit box, then the Max Turn On field will become available.

0 Oliver Mcconnell over 7 years ago in reply to Zhiyuan Hu

Prodigy 120 points

The problem is not setting the value there, but going into the Fault Responses window and turning on the glitch filter for Time On Max. The option to enable that is greyed out so if it reaches that fault where it never turns on, it wont do anything because I can't enable the glitch filter for that specific fault.

0 Zhiyuan Hu over 7 years ago in reply to Oliver Mcconnell

TI__Genius 9845 points

TON_MAX fault doesn't have glitch filter. You can still configure fault response such as shutdown immediately.

The Max Turn On period setting is not configured in the glitch filter, but in the Turn On Timing window (under Turn On Delay)

Power management

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UCD9090 Fault Response