TPS2492: About design calculator

wenxing zheng

Prodigy 20 points

Part Number: TPS2492
Other Parts Discussed in Thread: TPS25982, CSD18532Q5B

Hello,

Attached is our design calculator about TPS2492,pls help to check it!

I have some question about it:

1. Can the "typ device SOA limit" be edited in excel? how edit it if can?

now the curve isn't right.

2. The Rdson means the value what the MosFET has when the Tj(for example 125 deg) @vinmax=15V?

3. these SOA current value get from MOSFET curve when the Vds=Vinmax?

4.In step 4,derated SOA/PLIM is yellow now, what formula can get the value of derated SOA?

Are there any unreasonable parameters in our design that trigger yellow?

5. How can we get all formula in the design tool?

Thank you！

TPS2492_Design_Calculator_REV_B_12V.xlsx

over 3 years ago

0 Avishek Pal over 3 years ago

TI__Mastermind 40950 points

Hi Wenxing,

Thanks for reaching out to us. We will get back to you by today end of the day.

0 Avishek Pal over 3 years ago in reply to Avishek Pal

TI__Mastermind 40950 points

Hi Wenxing,

Happy New Year !!! Sorry for the delay in getting back to you...

First of all may I know the reason of selecting a 80 V controller and 40 V MOSFET for a 12 V, 10 A application in spite of having integrated eFuses like TPS25982 in Texas Instruments?

Please see the responses in the order of your queries.

The "typ device SOA limit" can't be edited in this design calculator. May I know why are you thinking the curve is not right? It's derived based on the following parameters,
1. Current limit set poin,
2. power limit set point,
3. Input voltage.It's also explained in the page 22 of the datasheet.
Yes, it should be calculated using these to data.
Yes.
Please refer to this app note. https://www.ti.com/lit/an/slva673a/slva673a.pdf I have edited the design calculator. Please see and let me know if there is any query.TPS2492_Design_Calculator_12V_Edited by TI.xlsx

0 wenxing zheng over 3 years ago in reply to Avishek Pal

Prodigy 20 points

Hello，

Happy New Year !

Our design needs to support Vin=12V or 24V，so we select 40V MOSFET and TI's local FAE recommend TPS2492 to us.

About below SOA curve,

1.the typ device SOA limit curve has met the selected MOSFET CSD18513's SOA ?

2..The temp derated FET SOA(t=Tfalut) curve has covered the typ SOA limit curve, so these parameters are suitable?

So We can think the MOSFET is suitable , as long as the derated SOA curve covers the typ SOA limit curve?

Are my understanding right？

0 Avishek Pal over 3 years ago in reply to wenxing zheng

TI__Mastermind 40950 points

Hi Wenxing,

Please let me know the maximum input voltage of your design. MOSFET SOA margin needs to be verified at the maximum input voltage. The modified design calculator attached in the previous post is fine for 12 V design. However, it is necessary to look at the SOA margin for input voltages more than 12 V.

0 wenxing zheng over 3 years ago in reply to Avishek Pal

Prodigy 20 points

Hello,

Input voltage needs to meet 12V or 24V in our design. The maximum input voltage is 26.4V when the input is 24V. And the load current is 5A when the input is 24V. Other paraments are identical with 12V input.

0 Avishek Pal over 3 years ago in reply to wenxing zheng

TI__Mastermind 40950 points

Thanks for your reply. Then, we need to select a MOSFET considering VINMAX as 26.4 V. I will search a suitable MOSFET and will get back to you.

0 Avishek Pal over 3 years ago in reply to Avishek Pal

TI__Mastermind 40950 points

Please use CSD18532Q5B. It will satisfy all of your design criteria. C_TIMER should be 20 nF.

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TPS2492: About design calculator