TPS23880: Heat dissipation higher than on EVB

Silvio Gehri

Part Number: TPS23880

In my design, the TPS23880 gets hotter compared to the EVB. However, I cannot find any significant difference, so I wonder if e.g. a different MOSFET or some 'unfortunate' register settings can cause this higher heat dissipation.

Thanks in advance for your support.

TPS23880 design.pdf

over 5 years ago

0 Penny Xu over 5 years ago

TI__Genius 15685 points

Hi Silvio,

The schematic looks good to me. Did you run the test under the same condition for your board and EVM? What's the temperature of TPS23880 on your board and on EVM? Thanks.

Best regards,

Penny

0 Silvio Gehri over 5 years ago in reply to Penny Xu

Prodigy 100 points

Hello Penny,

Thanks for your reply. Also good to hear that the schematics are basically ok. I was worried that maybe the pins of the 6 unused ports (3...8) are wrongly connected and maybe an input was oscillating or an output 'shorted' to GND...

Both, the EVM and my board were running in idle mode, i.e. the SRAM is loaded but no PD load was connected.

I don't know (yet) how the registers are set, but will run some comparison as soon as I have access to it. Do you think that 'unfortunate' register settings can cause the excess heat?

Best regards, and my best wishes for 2020 to you and your family!

Silvio

0 Penny Xu over 5 years ago in reply to Silvio Gehri

TI__Genius 15685 points

Hi Silvio,

Different register setting should not affect the device temperature and you actually can calculate the temperature rise based on thermal resistance. BTW, did you connect the TPS23880's thermal pad to a solid ground plane on your board? Thanks.

Best regards,

Penny

0 Silvio Gehri over 5 years ago in reply to Penny Xu

Prodigy 100 points

Hello Penny,

The thermal pad is connected to planes in the 4-layer PCB using 18 vias. However, the PCB is not too big, and the planes are around 22 x 28mm only.
However, why should the TPS23880 generate heat while non-active (idle)? Sure it is powered by approx. 54V, so typ. 10mA create about 0.5W. But it doesn't explain the difference to your EVB.

Best regards, Silvio

0 Penny Xu over 5 years ago in reply to Silvio Gehri

TI__Genius 15685 points

Hi Silvio,

Can you send me your PCB layout and thermal image of your board and our EVM? Thanks.

Best regards,

Penny

0 Silvio Gehri over 5 years ago in reply to Penny Xu

Prodigy 100 points

Hello Penny,

Happy New Year to you and your family!

Here are the layers as PDF, and the zipped Altium PCB document.2273.Q110 Main Board Artwork.PDF Beltpack.PcbDoc.zip

0 Silvio Gehri over 5 years ago in reply to Silvio Gehri

Prodigy 100 points

and the thermal image when in idle mode.
Note:

CPU (LPC4350) in the top middle
DC/DC on the left side
Ethernet switch on the right side
TPS23880 in the center

0 Penny Xu over 5 years ago in reply to Silvio Gehri

TI__Genius 15685 points

Hi Silvio,

I compared your board to EVM. Your board has an isolated ground for TPS23880, so the ground plane is smaller than EVM and the number of thermal via under TPS23880 is less than EVM. These are the 2 main reasons that TPS23880 on your board is hotter than on our EVM. Thanks.

Best regards,

Penny

0 Silvio Gehri over 5 years ago in reply to Penny Xu

Prodigy 100 points

Hi Penny,

Thank you for your help - very much appreciated.

Best regards, Silvio

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TPS23880: Heat dissipation higher than on EVB