UCD90160 TURN_ON delay is not correct

Kevin Chen(TPE Analog FAE)

Other Parts Discussed in Thread: UCD90160

Hi all,

My customer has problem about turn on sequence.

Both ON/OFF config of Rail#2 and Rail#3 are 0x02 (Auto Enable), and Rail#3 will be turned on after 100ms (Rail#2 PWR_GOOD).

And there is a extra long delay(about 160ms) on Rail#2, it makes Rail#3 delay more.

But, Rail#2 rises to PWR_GOOD level at very beginning. I don't know where the extra long delay come from.

If we disable Fault log for every Rails, the sequence is normal, there is no extra delay on Rail#2.

How does it happen? Below is the waveform.

Thanks,

over 10 years ago

0 Zhiyuan Hu over 10 years ago

TI__Genius 9845 points

Is Rail#2 controlled by UCD90160? It will be helpful if the Rail#2 EN signal is also shown on the waveform.

Thanks,
Zhiyuan

0 Kevin Chen(TPE Analog FAE) over 10 years ago in reply to Zhiyuan Hu

TI__Prodigy 150 points

Sorry, I make a mistake.

Rail#2 doesn’t have EN pin.

It’s hardware enable in our system.

Since PWRGD signal can’t be observed directly, we set pin 22 to present Rail#2’s PWRGD signal.

0 Zhiyuan Hu over 10 years ago in reply to Kevin Chen(TPE Analog FAE)

TI__Genius 9845 points

The UCD90160 device has an initialization time, typically 20 ms. If the fault log is corrupted, additional time is required to erase the corrupted fault log. The reason of the fault log corruption is that the 3.3V power drops before the device finishes writing the flash. So when fault logging is disabled, there is no corrupted log to erase, and there is no extra delay.

The solutions would be increase V33D capacitance of UCD90160 and enable brownout function. Please refer to datasheet page 29.

Thanks,

Zhiyuan

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UCD90160 TURN_ON delay is not correct