TPSM84824: tpsm84824

APARNA MANE

Part Number: TPSM84824

Dear Ti. team ,

We are using this TPSM84824 IC in our board,. design for 5V output , 2A lamp load .

We observe that body temperature of ic going upto 76-81 degree celcius within a 5-10 minutes and get stable at this point .

Same observation we face in Evalution board also TPSM84824EVM .

So please suggest any additional heatsink is required for this IC ?

Please guide us .

from,

Aparna

over 6 years ago

0 Denislav Petkov over 6 years ago

TI__Mastermind 19101 points

Hello Aparna,

The IC is actually rated for 150C maximum junction temperature.

What is the ambient temperature for your application?
Is it possible to share the schematic and the layout for the TPSM84824 circuit?

Cheers,
Denislav

0 Denislav Petkov over 6 years ago in reply to Denislav Petkov

TI__Mastermind 19101 points

Hello Aparna,

I checked some data from the evaluation board (EVM).
For 12V input, 5V output, 2A load, 1.2MHz switching frequency, standard EVM, the temperature rise on the IC should be about 22C above ambient.

Please confirm what ambient temperature you have and if possible to share the schematic and the layout for the TPSM84824 circuit.

Cheers,
Denislav

0 Denislav Petkov over 6 years ago in reply to Denislav Petkov

TI__Mastermind 19101 points

Hello Aparna,

The IC junction temperature will depend on the amount of copper you have on your board. The numbers I provided above are for the standard EVM layout.

Let us know if you want us to review your board layout or if you have additional questions on this topic.

Cheers,
Denislav

0 APARNA MANE over 6 years ago in reply to Denislav Petkov

Prodigy 30 points

1. Pcb in which IC temp. increased upto 76-81 degree celcius in this AGND and PGND are not getting shorted .
2. In other 3 PCBs 3nos are checked in these Temp. goes upto 55degree celcius , (ambient temp. 28 degree celcius ) . --In these AGND and PGND points are getting short .
3. as per datasheet these two points are not to be short , these are internally shorted in IC .
so please confirm , how these are getting short in IC . Is there any method to check these ICs before soldering .

0 Denislav Petkov over 6 years ago in reply to APARNA MANE

TI__Mastermind 19101 points

Hello Aparna,

The AGND to PGND connection is made internal to the device so no external connection to PGND is necessary.

There is a board layout example (see section 10 of the datasheet, page 24).
If you measure AGND to PGND resistance on the module before soldering, the two terminals should be connected.

In terms of thermal performance difference between boards, it is important to make sure the module is soldered down well to the PCB. If you don't have good solder coverage it will affect the heat transfer from the module to the PCB.

Cheers,
Denislav

0 APARNA MANE over 6 years ago in reply to Denislav Petkov

Prodigy 30 points

1)Pin no. 23,9 and 3 are AGND , we measured the resistance between AGND and PGND in three NEW ICs ,but these are open .

In datasheet pg. no. 11 block diagram of IC is shown , in this also these 2 grounds are shown shorted ,

2)In 16 assembled boards if I measured the resistance between AGND and Pgnd it is short . ----- so heating of IC with 2A lamp load is 44-45 degree celcius ambient temp. is 24degree celcius .

3) Since we have found one board in which these two grounds were not short , so IC is getting heat up about 76to 81degree celsius within few minutes . so please guide us

Before soldering we check 3 ICs but there is no short between AGND and PGND .

for reference schematic is attatched.

0 Mandar Mahajan89 over 6 years ago in reply to Denislav Petkov

Intellectual 345 points

Hello Denislav ,

This is Mandar from Arrow Electronics . We are supporting M/s Aparna here .

the Temp related issue is cleared now .

the only issue / observation remains :

During checking , if we check the Shorting between AGND & PGND on a fresh IC (without soldering on board ) , customer do not observe the continuity on the multi meter .

whereas , once we solder the IC , we get the proper internal shorting of both the pins .

Please confirm if this is OK or we need to get the shorting without soldering as well .

Regards

Mandar

0 Denislav Petkov over 6 years ago in reply to Mandar Mahajan89

TI__Mastermind 19101 points

Hi Mandar,
The AGND and PGND should be connected internally on a "fresh" module. Can they double check the measurement and confirm one more time please?
Cheers,
Denislav

0 Denislav Petkov over 6 years ago in reply to Denislav Petkov

TI__Mastermind 19101 points

Hi Mandar,
Do you have an update on this? I am wondering if we can double-check the AGND to PGND connection on a fresh unit.
Thanks!
Denislav

0 Mandar Mahajan89 over 6 years ago in reply to Denislav Petkov

Intellectual 345 points

Hello Denislav ,

I have requested customer to check and revert here on the forum . i have also arranged 10 fresh samples for them to evaluate .

Regards

Mandar

0 Denislav Petkov over 6 years ago in reply to Mandar Mahajan89

TI__Mastermind 19101 points

Hi Mandar,

Thank you so much. I will close this thread for now. Please post here once you have more updates and this will re-open the conversation.

Cheers,
Denislav

0 Mandar Mahajan89 over 6 years ago in reply to Denislav Petkov

Intellectual 345 points

Sure Denislav.. thank you very much for your support . the IC is running OK at customer end now .

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TPSM84824: tpsm84824