TPS2388: Reset timing inquire

Eric Fang1

Part Number: TPS2388

Dears,

I saw the datasheet define tRESET was 1-5us, but seems like this time is indicate with internal 1-μs to 5-μs deglitch filter?

Should I measure this value necessary?

Is there any place write the system reset time? because I check with scope it's about 500ms.

Eric

over 3 years ago

0 Darwin Fernandez over 3 years ago

TI__Mastermind 40905 points

Hi Eric,

The 5us deglitch filter is mainly to prevent any fast transient from causing a false reset. In addition RESET should be fast reacting in that asserting RESET low should turn off all the ports relatively quickly and less that 500ms. Can you confirm? Thanks!

0 Eric Fang1 over 3 years ago in reply to Darwin Fernandez

Intellectual 620 points

Hi Fernandez,

So the 1~5us deglitch filter is internal function? (see the figure as below)

If we can guarantee all the ports turn off less that 500ms when RESET asserting, that means reset function is ok?

Eric

0 Darwin Fernandez over 3 years ago in reply to Eric Fang1

TI__Mastermind 40905 points

Hi Eric, that is correct. When RESET is asserted, all 8 channels should turn off less than 500ms. Instead i recommend looking at the tp_off_rst spec. Thanks!

0 Eric Fang1 over 3 years ago in reply to Darwin Fernandez

Intellectual 620 points

Hi Fernandez,

We let device reset and get waveform, can you help to check reset timing about 473ms is ok or not?

And we check power on waveform as below, can you check if any warning?

Eric

0 Darwin Fernandez over 3 years ago in reply to Eric Fang1

TI__Mastermind 40905 points

Hi Eric, you should probably look at the gate of the external FETs if you wanted to see the reaction time when the PSE port begins to off. So i recommend looking at the RESET pin and also the GATE pin of the IC. I'm don't believe 3.3V iso PSE waveform shows the PSE reaction to a RESET asserted. Thanks!

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TPS2388: Reset timing inquire