TPS56637: X marking on physical component

Hi Matt,

What is the fail phenomenon? 

Yes, X should be the prototype version not the final production version. For the prototype version, we have the APL process so distributor may have the chance to have these samples. But I don't think X samples will fail. So I am wondering the fail phenomenon.

Thanks,

Lishuang

Hi Lishuang,

Thanks for the fast response.

The Failure mode that we are seeing is that when the device is powered up with the enable pin not connected the output of the device does not come on. If we ground the enable pin to pull the signal LO than the output of the device is enabled.

This only has occured on the X marked devices and i have seen no similar issue with the non prototype labled components. What is the APL process if you are able to explain?

Thanks,

Matthew

Hi Matthew,

Can I double check the failure mode with you? The device will no output when the enable pin is floating? But the device has output/enabled when pulling EN to low?

APL means Accelerated Product Launch. Before final production samples release to market, we will release some engineering sample after checking that there is no big issues (But may have some issues not founded). With engineering samples, customer can use it to do functional check but TI doesn't allow these to final production. 

Thanks,

Lishuang

Hi Lishuang,

Thanks for the fast response again - Yes that is the failure mode, when the enable pin is floating the device has no output but if the enable pin is pulled low the output is enabled.'

Thanks for APL explination - The product description and part number from the distrubuator is the same as the non prototype component so i wasn't aware i had purchased not final production product.

Thanks,

Matthew Henderson

Hi Matt,

That doesn't make sense even with non prototype component. 'when the enable pin is floating the device has no output but if the enable pin is pulled low the output is enabled.'

1. Can I check the SCH first?

2. Can you also ask customer to test the waveform including VIN, EN, SW and Vout both under EN is floating and EN is pulled low?

I don't think X samples have the EN configuration difference.

Thanks,

Lishuang

Hi Lishuang,

I'll gather the infomation now with regards to the schematic and signals. however is this qoute below not related to the issue i am seeing?

Plain text "Hi Jonathan,

These X56637 samples are APL samples with PG1.0 die. Now our RTM samples are using PG2.0 die. So we don't recommend to use these X56637 samples for production, even for functional checking.

We should advice customer to contact their vendor so as to get RTM samples with T56637 marking"

Hi Matt,

Yes, as you captured, we don't recommend to use X56637 for production or for functional checking.

But I don't think EN pull low, it has output even using X56637. That is my concern.

Thanks,

Lishuang