TPS65133: this ic heats up excessively and stops working within few seconds

HI,

I have notified our expert regarding this topic. Please expect a response by 9/30/19.

Thanks,

Aaron

Hello Mukul,

There is no special requirement to use this device. Unfortunately, there is not enough information in your post for me to be able to see what what may be causing the malfunction. If you can provide your circuit schematics and operating conditions such Vin, load current etc., I will be happy to review to see if I can spot something that may be causing the issue.

Kind Regards,

Liaqat

Hello Liaqat I am sharing the circuit diagram 

Hello Mukul,

Schematics wiring seems correct. The only thing I can think of is perhaps inductors L1, L2 saturation current ratings may not be high enough and that can be possibly cause higher current through the internal switches.

Are these 4.7uH inductors and what is the saturation current rating for them?

Also, what is load current on VPOS and VNEG?

If you remove the load completely, does the device regulate VPOS and VNEG properly?

Please let me know the answer to these questions to aid in further debug.

Kind Regards,

Liaqat

Hello Mukul,

In addition to questions above, what is VIN voltage to the device?

Thanks,

Liaqat

Dear Liaqat,

Specs of Inductors are: -  MLZ2012M4R7WT - High-Frequency Inductor, 4.7 µH, MLZ Series, 500 mA, 0805 [2012 Metric], Multilayer, 0.3 ohm by TDK

Load current: - I have not added any loading circuit. As you can see in the schematic that only an LED followed by a 470 oHm resistor @ VPOS pin is given.

Vin - I was applying 5volt as VIN.

"If you remove the load completely, does the device regulate VPOS and VNEG properly?" - As mentioned earlier no load is there in the circuit.

When I applied VIn =5V, the LED used to glow and after a few seconds, it stops glowing and excessive heat was generated in the IC. I have tested 2 boards and both of them gave the same consequences.

Note :- I have shorted AVIN PVIN and EN pins. Is that correct? KIndly tell me about the input given to EN pin? 

Hello Mukul,

Tying EN to VIN=5V is not a problem. It can be anywhere from 1.2V to VIn.

I wanted to know about the load current, the inductor saturation current specification and Vin voltage to ensure that peak inductor current does not exceed its saturation current specification but if there is no load (only LED) than there is no concern from that point of view. I am at a loss as to why the device is heating up in this case. Only possibility I can think of is perhaps some board assembly issue.Sorry, but I don't have any other suggestions or ideas.

Kind Regards,

Liaqat

Hi Liaqat,

Thanks for your precious time. One request, can you please send me the schematic and layout both for any working TPS65133 IC. I will test the design sent by you and also compare where I am going wrong. Maybe I have purchased a poor quality inductor or capacitor. 

Thanks

Mukul Singh

Hello Liaqat,

Finally my board started working. I used same components and the same design but this time I have not shorted VIN and EN pins. I followed the TPS65133 users guide provided by you.

Thanks

Mukul SIngh