TPS54531: Reliability question (HAST)

Hi,

The recommended operation temperature is –40°C to 150°C, not 85°C.

I think it depends on the input voltage whether it can be used on your application, this max input voltage is 28V for this IC.

What is the company? And where are TPS54531 used? What is the input voltage? What is the application?

And for the 20 year life time, I am not sure. It needs our CQE to give the comments.

Shawn

Hi Shawn 

Thank you for the reply. A few follow ups

1. 150C seems to be the operating junction temperature (section 7.1). I'm not sure that is the same as operating ambient air temperature. The operating temperature in the package option addendum page of the data sheet give 85C for package TPS54531DDAR. Please correct me if I am still misunderstanding the datasheet. 

2. Our input voltage is max 24V. Its an industrial application used for solar water heating. We are already using it without problem. But our concern is the reliability for its life cycle. Hence the question about HAST and temp cycling and the automotive qualification. That question is still un-answered. Could anyone from your team give us a reply for that?

Thanks

Raghu

Hi Raghu,

Yes, it is the junction temperature, For the ambient temperature, it is decided by the VIN, VOUT, IOUT and Layout to make sure OTP is not triggered.

For question 2, I will forward to our CQE. 

Shawn

Hi Raghu,

Below is the data for life time, hope it is helpful.

And you can get more information on below website.

https://www.ti.com/quality/docs/estimator.tsp?OPN=TPS54531DDA&CPN=&partNumber=TPS54531#resultstable

Shawn

Hi Shawn 

Thanks for the data. But I am unsure of how to estimate life time from the data you sent. Could you explain? 

Vin = 24V, Vout = 12V, Iout = 2A

Also, when would your CQE be able to answer the HAST, temp cycling question about Automotive qualification? I will repeat the question below just to be sure :) 

1. It seems to me that TPS54531 is not automotive qualified. But its reliability information mentions that it has undergone JESD22-A101/JESD22-A110 test for THB/HAST and JESD22 A-104 for temp cycling 

 These looks like an automotive standards to me. Please correct me if I am wrong? Does this mean that for THB/HAST and Temp cycling it meets automotive reliability standards? 

Thanks
Raghu

Hi Raghu,

Below answer is from QRE,

"For JESD22-A101/JESD22-A110 and JESD22 A-104, they are test methods.

Though these test methods are used by automotive qual. requirement as well, but it doesn’t mean this device can meet automotive standards.

Besides test method, there are additional requirements (ATE temperature etc.) need to be satisfied for automotive qual."

Shawn

Hi Shawn

Thanks. That definitely helps. Could you also be able to explain how I could interpret the data you sent for the lifetime?

Is the FIT value of 0.5 a reference? Its too low to be the actual value. Do I have to calculate the FIT and MTBF from the ELFR DPPM? I'm not sure how to interpret these values? 

Thanks

Raghu

Hi Raghu,

Sorry, I also don't know the meaning of these value. I will ask CQE or QRE.

Shawn

Hi Shawn 

Perhaps you have misunderstood my question. I realize that the FIT and MTBF data come from real HTOL data.

Let me explain my question again- 

From the data I see that the FIT is 0.5% and MTBF is 1.96 x 10^9. 

These give very unrealistic numbers when calculating the expected lifetime of a product. Even for a simple part like a capacitor the FIT is around 16.5 and MTBF is around 6918 years. This gives a 99% probability that it will last 10 years. Considering this how can the FIT for a complicated buck be 0.5%. 

I don't understand how to interpret the data. Can the QRE help to explain those numbers? 

-Raghu

Hi Raghu,

Below is from QRE:

The process for TPS54531 is a generally mature process.

During the past years, sample size 50483 combined all the devices stressed HTOL together to get MTBF/FIT for this technology level.

 Shawn

Hi Shawn

I sent you an email this morning. 

Thanks