TPS389006-Q1: ACT is pulled down by TPS389006-Q1

Shubiao Wang

Intellectual 1490 points

Part Number: TPS389006-Q1
Other Parts Discussed in Thread: TPS389006

Hi there,

Customer is working on tps389006-Q1 sequence test.

we found a ACT is pulled down by itself for about 1.5ms, the waveform is shown below.

test condition.

1. if the ACT rising edge is ahead of VDD rising edge

2. the ACT signal is pulled down when the VDD reaches about 3.3V.

As the ACT input signal is also used as other devices enable signal, it results in an abnormal on/off for the other device.

please help to double check if this is a normal operation of tps389006-Q1?

BRs,

Shubiao

over 1 year ago

0 Mathew Jacob1 over 1 year ago

TI__Expert 5900 points

Shubiao,

This is expected since BIST is run after VDD crosses POR. It is recommended to send ACT low to higher after the BIST startup duration which is given in the timing section in the datasheet.

Regards,

Mathew

0 JJ He over 1 year ago in reply to Mathew Jacob1

Prodigy 220 points

Hi Mathew,

Thanks for your quick response.

If the ACT is pulled high before VDD POR, would ACT be pulled down by TPS389006 itself to meet the timing requirent?

0 Andrew Kutzler over 1 year ago in reply to JJ He

TI__Genius 13530 points

Hi JJ,

I'll investigate and let you know.

Thanks,

Andrew

0 Andrew Kutzler over 1 year ago in reply to Andrew Kutzler

TI__Genius 13530 points

Hi JJ,

Based off of the device functional modes (figure 8-8 pg 13), it makes sense that ACT is de-asserting itself then pulling itself back up. After VDD hits POR, the device goes into BIST (built in self test) before fully turning on. The rising edge of ACT is needed to transition to the sequence monitoring block.

Thanks,

Andrew

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TPS389006-Q1: ACT is pulled down by TPS389006-Q1