TPS2482: Thermal calculation

In equation 4 you calculate 4.17 mOhm on page 23/59

Then you choose 3mOhm in stead of 4 mOhm. Should you not calcaulate the Max current based on the choosen sense resistor ?

So when I choose 4 mOhm you get a current of 10,41666667 A

In equation 7 how is the RDS choosen of 6.45 mOhm ?

I take a look in the datasheet CSD18503Q5A page 1 of 3

RDS(on) Drain-to-source on-resistance VGS = 4.5 V 4.7 mΩ so 4.7mOhm times 1.39 taken from figure (graph) 8 Normalized On-State Resistance vs Temperature @ 100°C

gives 4.7 mOhm x 1.39 = 6.533 mOhm ?

With kind regards

Marcel

Hi Marcel,

Please go through these videos and app note. 

https://training.ti.com/node/1133677

https://training.ti.com/node/1133673

https://training.ti.com/node/1133664

https://training.ti.com/node/1133681

Robust Hot Swap Design (Rev. A) (ti.com)

Design calculator with equations shown is NDA restricted. I can't share in a public forum. Please provide your design calculation sheet. I will review and get back to you. 

Hello Avishek Pal

For now I am following the example in the TPS2482 datasheet om page 24/59 

For CSD18503Q5A, ZθJC of 0.3 can be used for fault times below 10 ms. I dont understand how you get to this number?

Using this datasheet

https://www.ti.com/lit/ds/symlink/csd18503q5a.pdf?ts=1668596056146&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FCSD18503Q5A

figure 1: Transient Thermal Impedance. I assume the Single Pulse Line. I look at the x-axis tp Pulse duration at number 0.01 = 10ms long pulse.

Then I look where this line crosses Single Pulse line and read out the y-axis ZθJC Normalized Thermal Impedance is about 0.8 times RθJC.

In the TPS2482 datasheet a number of 0.3 is mentioned what would be corresponding with a 1ms single pulse.

With kind regards

Marcel Loos

Please use the data marked in yellow. 

Hello Avishek Pal

For now I am following the example in the TPS2482 datasheet om page 24/59 section

3. Choose the Power Limit, PLIM, and the PROG Resistors, RPROG1 and RPROG2

How is ZθJC choosen ?

In the graph for the CSD18503Q5A I see a value of ZθJC = 0.8 at 0.01 (s) Pulse duration (10ms)

In the graph for the CSD18503Q5A I see a value of ZθJC = 0.3 at 0.001 (s) Pulse duration (1ms)

On page 25/59

4. Choose the Timer Capacitor, CT

In this section they calculate  Ton(max) = 1.58ms, on the graph in between 0.001 and 0.002 (s) I read a value ZθJC = 0.4

In this section they calculate tFault = 6.6 ms, on the graph in between 0.001 and 0.01 (s) I read a value ZθJC = 0.8

Is what I am doing correct?

With kind regards

Marcel Loos