CSD19536KCS: Power Cycle (ΔTj)　and　Heat Cycle (ΔTc)

Hello John-san,

Nice to hear from you and thank you again for your reply. I understood TI doesn't have RBSOA and SCSOA for FET.  Do you think that I don't  need to care about RBSOA SCSOA, and power cycle(Thermal cycle) of FET?  Is the FET life time is just MTBF/FIT if I use those FET within data sheet specification? What is the difference of the methodology of the power cycle failure between FET and IGBT?

Best regards

Tomomitsu Sano   

Hi Sano-san,

I consulted with our reliability engineer. Below is the summary of our discussion. Can you share more details about your application and requirements? Is this for a 48V motor drive or battery management system?

Q: Can you calculate lifetime of power cycle of CSD19536KCS, if I send the specification of our using (operating) pattern of the FET?

A: In general, the only way we can calculate lifetime from Power Cycle is by Coffin-Manson, which is also used for Temp Cycle.  AEC Q101 highlights this as well.  We would need to know their cycles per day, temperature delta, and expected lifetime and we could determine if IOL cycling covers that lifetime.

Q: If we use CSD19536KCS in the case of within the safe Operating Area, what years is the expected life time?

A: I need more help to answer this one.  For IC we are designing for 100000POH <50FIT @ 105C as a minimum….I will try to find out what our discrete FETs are designed to.

Q: Is the FET life time is just MTBF/FIT if I use those FET within data sheet specification? What is the difference of the methodology of the power cycle failure between FET and IGBT?

A: The FIT/MTBF shows process maturity but is not device specific.  We did however run these units through 1000hrs 150C biased testing.  If we know what the average use condition for the customer we can use the Arrhenius equation to determine life time in years.  I am not sure what they mean by the second part of the question.

Please share more information about your application and requirements. I will update you as soon as I have more details.

Best Regards,

John

Hi John-san,

Thank you for your answer and information. I will use those FET for 48V battery management system. In the near future I will send operation pattern of FET to TI for calculation of power cycle life time. TI have Power cycle data ( or RBSOA and SCSOA data) for IGBT doesn't it?. However TI doesn't have those data for FET. Why everybody doesn't care about FET power cycle data? Don't we need to care about FET power cycle life time?

Hello Sano-san,

TI does not make any IGBT devices and we never have. We only make low and mid voltage power MOSFETs. As far as I know, no FET vendors spec RBSOA or SCSOA because secondary breakdown is very uncommon in silicon FETs. We do provide single pulse UIS/avalanche ratings for our FETs as explained in the blog at the link below. As long as you operate the FET within the SOA curves provided in the datasheet, it should operate reliably in your system. Please provide your operating conditions and we'll do the lifetime calculations.

Best Regards,

John Wallace

Hello John-san,

I greatly appreciate your help. I would like to provide our operating conditions after several weeks. 

Can this thread remain open until then?

Best regards,

Tomomitsu Sano