TPS563300: IC burn out when input 24V supply is connected

I missed giving part nos. for C3 and C4 (47uf / 25V) in my previous post - C3216X5R1E476M160AC.

Hi Pradeep

The failure happens when hot-pulg-in right? Can you please measure the waveform of Vin, SW when hot-plug in ? And see if there is any overshoot/ voltage spikes.

Thanks and best regards.

Hi Gui,

The failure happens at hot-plug in as well as when input supply is started. I am using SMPS from 'Meanwell', model no. LRS-75-24. I have already observed waveforms at the output of this power supply. The output of this power supply is quite clean and soft starting. I have not observed any overshoot on output of power supply. 

However, I have not checked at 'SW' pin of IC as I thought there is no load connected so this should not be problem. Do you want me to check waveform at SW pin? do we need any minimum load to be connected at output?

Thanks,

Pradeep

Hi Pradeep

Can this issue be re-produced? It would be helpful to analyze if there are waveforms.

Thanks and best regards.

Hi Gui,

Yes, issue is reproducing randomly but I do not have waveforms at the instant of IC burning out.

Here are waveforms in normal operating condition without load.

I have multiple power supplies on my custom board. 

From 24V input, three supplies are generated:

1. +12V supply for external load: 1.5A of external is expected to be connected on this power supply. This is designed around TPS563300 which is burning out.

2. Battery charging supply of 13.7V using LM317. 

3. +12V supply for internal circuit power. This is designed around TPS54531 chip/ This is used for generating +5V power supply which is designed using TPS564252 chip. From +5V again I derive +3.3V power supply using NCP1117-3.3V.

I have seen TPS54531 also blowing up once when hot plugged in and at that time TPS563300 was removed from board.

Both TPS563300 and TPS54531 have max. input voltage as 28V. Do you suggest I should use high max. input voltage ICs for 24V nominal input supply? 

Thanks,

Pradeep

Hi Gui,

I will like to give one more input after going through number of queries on this forum about different DC/DC converters. In one of the issue resolution, it was suggested to connect bulk capacitance at input if distance of input supply pin is more than 5cm from chip input pin. In absence of this, due to inductance of long trace at input, there may be ringing at the input which may damage the chi[. Referring to this, on my custom board, input to TPS563300 is about 5cm from input connector and to TPS54531 it is about 10cm. Does this call for including bulk capacitance in my case?

Request you to reply at earliest as we are now considering various other options for this problem.

Thanks,

Pradeep

Hi Pradeep

You can measure the waveform of Vin when hot-pulg in and check is there any overshot on Vin pin.

Thanks and best regards.

Hi Gui,

Input waveform is pasted above in my reply - "Input Waveform 24V supply". I don't see any overshoot on Vin. Connecting bulk capacitor of 220uf at input did gave some improvement. IC TPS563300 had no issue with input hot plug in at no load condition. But after connecting load of 1.2A on 12V output, IC failed on few cycles of input on/off operation. No hot plug in, just on/off of input supply. Schematics is also pasted above. Can you please check and comment if something wrong on output section?

Thanks,

Pradeep

Hi Himanshu,

I am facing the same issue. Out of my 10-boards, 3-boards got randmoly burn out this ICs in similar way. I am providing operating voltage 12V input (Stable source) and converting 12V to 5V. Device it taking maximum load current 1A only.

Further to more insight, I removed the chipset and checked, it is giving shorting between VIN and GND pins.

Even input pin to main Power input tracelength is less than 1 CM.

As you know we can't measure the input waveform when it burn-outs as input voltage get shorts with GND. What could be the possible route cause here?

Best Regards,

Hitesh

Hi Hitesh,

Is the device burning out near IN pin? If yes, a very common way this can happen is when you reverse the polarity of input. I would till suggest to use a fuse with lower current rating as you are not able to measure the current reliably during the short.

Regards,

Himanshu 

Hi Himanshu,

There is no way for reverse supply. I am generating from 15V to 12V buck converter and it never get reversed. I am worry because our 200-pilot boards are already in production.

Strange is that its input voltage never more than 12V. Do you think any TVS diode or any such protection will help?

Best Regards,

Hitesh Gambhava

Hi Hitesh,

I am little confused here. Which IC/ICs are burning out? Are there multiple devices which are going bad?

Hi Himanshu,

TPS563300 blowing out. I am mentionting that there is zero possibility of supply reversal in my case.

Best Regards,

Hitesh

And which is the circuit for which it is blowing up? Is it for 24V to 12 V stage or 12V to 5V stage or both?

It is at 12V to 5V stage.

Best Regards,

Hitesh

So there is no fuse or any kind of protection added on the input side? You may want to try with a fuse. Also, please share the correct waveforms, whatever waveforms and protection circuit you had shared earlier was for 24V to 12 V stage.

Hi Hitesh,

Do you still support on this issue? If yes, please do respond.

Regards,

Gautam