TPS62142/62143* OVER CURRENT PROTECTION?

I would not recommend going back to the older, larger TPS62110 without some more investigative work.  These new devices also have over current protection.

It's not clear from the description exactly what is going on.  Can you send waveforms of Vin, Vout, inductor current, and SW when they force an overcurrent?

Additionally, their layout should be checked as this is a common cause of failures for any switch mode converter.

Finally, at their current levels, the TPS62160 family provides a smaller solution size.

about TPS62142 evrething is just working fine until you have overcurrent condition for example if you accidently overload or short the +3.3V output voltage to GND the device stop functioning, just 0V output voltage that it !!! (no input overcurrent, no heating, nothing) 

even if you turning circuit off, wait some time and then turn on again, Just nothing happens !!! OUT = GND the only way to recover from this condition is to replace the part by other one (I have replaced this part at least 6 times may be much more) 

about TPS62143 the condition is even worse, it start working fine with very low input current (<0.05A @ 12V), and then from unknown reason after few minutes it just turn output voltage to be GND and nothing can help him to recover !!!

after replacing 2 TPS62143 I decide to make some patch and work with external 5V power supply based on TPS62110 and it works fine, all peripheral in my circuit working fine it means the circuit NOT cause overload or incidental current rise 

[the difference between operating conditions of those parts TPS62142

(FSW=GND)  while in TPS62143 (FSW left unconnected)  ] 

Please let me know if you have any solution ?

B.regards

Eli 

Again, I cannot help you unless you provide some waveforms of the devices.  When the short is applied in the first case and during normal operation in the second case.  

It's also important to check their layout against the datasheet recommendations.  They can also try testing the EVM in place of their design and see if they get similar results.

Quote:

Unfortunately I can not provide you waveforms because I don't have equipment with multiple measurement capabilities and digital save anyway like I said before the part is operation fine, I have good efficiency and even no heat at all anyway if you just short between +3.3V and GND (you can try it on your EVB) the part is gone like fuse !!!

 in second case the only difference is that FSW left unconnected (floating) I gues that somehow due to weak pull down resistor it cause the part to fast switching between the modes and born herself like in the first condition there is no abnormal conditions, and everything operates fine until the part is just gone

 Eli

I recommend that you go in your customer's lab and help him debug this.  When I short the output of the EVM, it goes to , then comes back once I remove the short.  It operates fine with no damage.

You might also look at their Vin supply to make sure that it is not current limited or moving above the abs max of the device.

The device can operate with the FSW pin floating but you might as well connect it to ground if you don't intend to toggle it.

See attached reply+design+layout

1033.NETVISION DESIGN.docx

Thanks for getting their board layout.  It doesn't look anything like the EVM.

I'm also assuming the layout pictures didn't come through properly since there are obvious errors.  The GND pins are not connected.  Tiny trace widths are used for the routing of SW and Vout, etc.  They need to follow the layout recommendations in the D/S.  They can order the EVM for a known good layout.

Yes, the FSW pin is not tolerant of Vin voltages.  It is recommended to connect it to Vout, not Vin.  This is noted in the datasheet.

i got it by mail.

please advise your e-mail address so i can send it to you

I think the doc file uploaded ok (you can check it), but I think the customer didn't print the layout view correctly, as there seems to be copper hidden.

In any case, you'll need to review the layout with the customer and instruct him how to do a proper power supply layout.  An improper layout can cause unexplainable failures like what he is seeing.

See attached

I ordered the EVM

8463.tNEXTVISION LAYOUT.docx