Hi waqar hyder1,

Welcome to e2e!

For reverse polarity protection, the device needs to have reverse current blocking capability+ diode in the GND path of the IC to block reverse voltage.

TPS25942 has integrated reverse current blocking FET so, it only requires one signal diode in the GND path to protect itself from reverse polairty.

One the other hand TPS259230 doesn't have reverse blocking FET integrated. So, you need to use an external reverse blocking FET + signal diode/FET in the GND path of the IC.

Our Latest device TPS25947x is exactly suitable for your requirement. It has integrated reverse current + reverse polarity protection. So, you do not need external components. TPS25947x  Withstands negative voltages on input up to (VOUT – 19 V).

Please let us know your feedback on TPS25947x

Thanks for your answer 

we need an automobile qualified part for our application, that is why we had chosen the TPS25940-Q1 version for our application. 

Does the part you recommend have a AEC qualified version and 5.5A + current capacity ?

Hi Waqar,

The proposed part TPS25947 is not Automotive Qualified. The part you have chosen TPS25940 is Automotive Qualified and is right part for your application.

To achieve reverse polarity protection, you can use signal diode in the GND path as shown below.

Thanks, could you also please recommend a automobile qualified part for the Diode in the ground path 

Hi Waqar,

We can support you on the Diode specifications required but not on the exact part number.

You need to use a 30V, 0.2 A diode as specified in the image shared earlier. 

Is FET instead of diode a better choice ? what is the trade off ? I imagine since this is in the ground path and not in the in the signal path, there is no concern on the power loss through the diode ?

Hi Waqar,

Yes you can use a FET instead of diode. The advantage you get is low voltage drop. 

If diode is used the power loss should not be a concern as you mentioned.  

Could you please clarify diode specs again, the 30V is that he reverse breakdown voltage and 0.2A m is that the IR or maximum reverse current ?