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Dear members,
I am designing a power circuit of converting 12V to 5 V
and I found TPS62130 broken for several times.
With the attached schematic, I can get 5 V output at first.
After a few hours, TPS62130 stop functioning and output voltage dropped to 0 V.
However, after I replaced the broken one with a new TPS62130,
the circuit can function again.
Here are more conditions which I can provide about the situation:
Did I made any mistakes on the schematic design?
I am looking forward to any replies and suggestions to improve the circuit performance.
Thank you.
Regards
Thanks for the reply Lubomir.
The input capacitor C2 using is TAJA226K006RNJ.
I choose tantalum cap as I refer to the blog below written by TI employee.
e2e.ti.com/.../what-is-that-giant-tantalum-cap-on-the-input-of-the-evm
The Input Voltage range is 11.7-12.2 V and should be stable
One more question to ask:
Does it matter if I connect the power source of 12V directly to Vin and Enable ?
Will it cause any voltage overshoots related to “hot-plugging” (which is described in the above blog as well)?
Finally, I would like to describe the situation when I find the chip is borken.
I used a loading of around 0.53 A for Vout in order to test TPS62130.
It was fine before and after I connected the PCB with loading.
However, after I turn OFF the 12 V power In, the chip can't function anymore after I turn ON the power IN again.
Please advice for the solution.
Hi Gordon,
you are right, there is tantalum capacitor but there is higher value to attenuate voltage spike during hot-plugins.
The small input capacitor is placed directly on the module TPS8268105.
So you have input cap but the value of the tantalum cap can be higher in this case. What is missing in your application is ceramic cap according to the datasheet recommendation page 15.
It seems that your design is copy of our EVM:
Maybe it is worth to order it and you can save time with re-layout of PCB. Unfortunately PCB layout has to be improved.
If you connect power supply directly to input cap you are probably using long cables. These cables has inductance which can cause high voltage spike during hot-plugging.
Best regards
Lubomir Fenic
Lubomir,
If you read the forums, you will find that this is actually a common and problematic issue with the TPS621XX and TLV621XX series. We went through probably 20 of these regulators that all mysteriously stopped working. Some would last a few weeks, others a few months, but they would all eventually die.
It would be nice if TI would do just a little investigation into this, as I'm sure it is something that could be fixed, and not that hard to reproduce, given time. These regulators have great specifications, they are just too unreliable to put in a product.
Good luck with your layout, but I think you'll find that no matter what you do, you'll end up with the same results. I would recommend looking at another part.
Here is the link to a related issue we had with the TLV62130 part.
https://e2e.ti.com/support/power_management/non-isolated_dcdc/f/196/p/418004/1516345
-Justin
Thanks for the reply, Chris.
Although the original intent was to connect to a car battery, the TLV62130 has also 'died' many times just sitting, operating with no significant load transients in a lab environment. A lab environment and board environment in which we have never had a single other regulator, linear or switching, have any issues ever. At first, we thought these random 'spontaneous death' issues must have been caused by a quick short circuit that we somehow missed (although technically, the 62130 is supposed to be able to handle one). This is what prompted us to perform the forced short circuit testing in the other thread, which clearly and quickly causes the 62130 to fail, often in a 'burn out'.
So then we thought, "okay, a short circuit event is unlikely to occur, we'll just live with it's short circuit performance". But the same random "spontaneous death" issues kept occurring. These are less easy to reproduce, because they happen randomly after the regulator will have often been working for weeks. I would also note that we added circuit protection just in case our lab power supply somehow sent out some transient that was never captured by our scope (or caused any problem with any other part ever). We put a 13V TVS diode before the regulator input.
I've sent you waveforms before. What you're asking for is waveforms of switch current which requires a $3000 DC current probe. Forgive me if that's not in our budget to help solve a problem which I firmly believe is not on our end. Additionally, it would be near impossible to capture any signal in the case of the "spontaneous death", only in the "short circuit burnout". We've already had to spend a lot of resources to re-evaluate other regulators and cram them into our design since they are lower switching frequency which require much larger inductors.
I genuinely hope someone at TI takes the initiative to do some basic testing, in the off-chance that a customer, whose simple test board schematic and layout has been shared, might have found an issue that could be a real problem. It cost us time and money to design to and away from the 62130, and we gave it every opportunity to succeed, but it always failed after some period of time. I would even consider returning to the 62130 in the future, if there were some explanation as to why it failed so many times, and what has changed to fix that. Or maybe the -Q1 has some redesigned circuitry that eliminates this issue (since it is listed as "automotive qualified" all over the spec sheet).
My apologies if my rant comes off as frustrated, because I am. It is just so hard to believe that no others of your many many customers have these issues. If you do find any issues that would be solved by a different version of the part, please let me know. If not, that's fine too. If you want to further the conversation in a different thread, let me know.
-Justin