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UCC27524: the output is pulled down

Part Number: UCC27524
Other Parts Discussed in Thread: UCC27624

Hi team,

My customer uses UCC27524 in their project. The customer has found that when doing a low temperature test (temperature below -20°C), the output of UCC27524 is sometimes pulled down, but at normal temperatures, the issue does not occur.
The output of UCC27524 is connected to a optical coupler and the current is 12mA.

Could you please help review and give some suggestions? Thanks in advance!

Below is their schematic.

The test waveforms.

Regards,

Ivy

  • Hi Ivy,

    This device's pullups and pulldowns have a fairly strong temperature dependence. At cold, the resistance should decrease significantly. We should investigate if the inputs are crossing a threshold due to this change. I would suggest measuring EN and IN during this test. Either way, this will tell us if the pulse is the device listening to the inputs, or if there is something else wrong. 

    Also, UCC27624 has much less temperature dependence. Maybe the customer can try testing with it instead?

    Thanks,

    Alex M.