TAS2505: Workaround of internal LDO start-up issue

Hello,

Our customer facing internal LDO ramp-up problem same as previous E2E sled.

We captured LDO rump-up waveform which output 0.6V around 800msec then rise it to 1.8V.

They follow power supply connection of Figure 22 in the datasheet. LDO_SEL is connected to SPKVDD, IOVDD is connected to AVDD 1.8V.

Now they need to fix this issue without HW change, because it is already in mass production factory.

One of successful trial was apply 2sec delay for releasing RESET by SW change.

Here are questions for you.

<Urgent>

1. When look into SLAU472 TAS2505 Application Reference Guide. Figure 2-7 POR Diagram.

To start device function, both of /RST and POR is needed. It seems just delay /RST will be right way to fix this issue.

What is your insight? Could you give us another workaround?

2. In our customer board, LDO can ramp-up from 0.6V to 1.8V after 800msec. Do you expect all of the device has this response?

If some of device cannot rump to 1.8V for a long time, we cannot go this workaround.

<Not urgent>

3. Our customer wants see updated power sequence requirement.

Could you show us updated Table 3-2. Power Supply Timing Parameters in SLAU472?

4. What is the root-cause of this LDO issue? And silicon revise plan.

Regards,

Mochizuki