PGA411-Q1: PGA411 boost not work in low temperature

Hi Sammi,

It looks like the boost is not turning ON at those low temperatures on that device. Is the device reporting any faults related to boost?

Did the customer try on multiple units?

Regards

Sharath.

Hi Sharath,

Customer found that the fault pin is pull high. But when read register DEV_STAT1&DEV_STAT3&DEV_STAT4, all value is 0, and no other fault report. This is the board layout by customer, multiple units have this issue. And no issue report out in room temperature.

Thanks.

Best regards,

Sammi

Hi Sammi,

What happens when the FAULTRES is pulled low (ignoring all the faults). Would the Boost work in this situation? 

Are the Boost components rated for -40C? (caps, diodes, inductor)

Please ask the customer to probe pins similar to Fig 75 of the datasheet. This could give us a clue. It is not obvious what is wrong here as I have not heard it from other customers. 

Regards

Sharath.

Hi Sharath,

When the FAULTRES is pulled low, the Boost work and stop working after a few seconds.

The Boost components are rated for -40C.

The plot of PIN VEXT  is indicated in the picture.

Hi Sammi,

It does look like the device transitioned to Fault mode. Can you ask the customer to read DEV_STAT1 to DEV_STAT7 and send it to us?

Please note that most of the bits are clear on read. So, these registers should be read only one time and report.

Regards

sharath.

Hi Sharath,

DEV_STAT1 to DEV_STAT7 are read 0, but I am not sure if data has been clear.

If it is 0, customer want to know under what condition that PGA411 will make fault pin high and register DEV_STAT1 to DEV_STAT7 as 0.

Thanks.

Best regards,

Sammi

Hi,

The device should report a fault when the FAULT pin is high. The fault has been cleared or the digital core has been reset. Can you ask the customer to read any other non zero registers to make sure the communication is okay?

Is this a startup issue? Is the setup working fine when it is running at room temperature and lowered the temperature to -40?

Regards

Sharath.

Hi Sharath,

Normally, register 5 and 7 are none zero, but they all return 0. Customer will confirm if the communication is normal.

I see you doubt it is a startup issue, but I have not see any additional description about startup in datasheet, could you kindly give more information about this startup issue?

Thanks.

Best regards,

Sammi

Hi Sammi,

Sorry, I meant to say whether this issue causing because of a start-up at Low temperature. I want to know whether the device works fine when it is already started and lowered the temperature to -40C. There are no known startup issues with this device.

Regards

Sharath.