INT - PMIC TPS65910 Radiation issue

Miteshkumar Dalabhai Patel

Intellectual 1900 points

Other Parts Discussed in Thread: AM3351, TPS65910

Hi Team,

One of my cusomer is working on consumer product where they are using TPS65910 PMIC for AM3351.

They are facing issue with radiation from TPS65910. Theyhave kept the provision for snubber, but not able to tune as per requirement. On spectrum we are able to see continous 3 MHz peaks till 100MHz at every 3MHz spacing, so it is confirm that noise is from power supply only.

Unit is exceeding the limits by some 5dB when went for the average scanning. In Quasi mode they were able to pass the unit in radiation also. To be safe we are trying to bring down the radaition by 10dB so unit can pass with enough margins.

Any suggestion from you guys will helps us to close the issue. Kindly help.

regards,

Mitesh

over 7 years ago

0 Miteshkumar Dalabhai Patel over 7 years ago

TI__Intellectual 1900 points

Hi Team,

Kindly find layout image as well. If require we can ask for PCB layout to customer.

regards,

Mitesh

0 Richard Solarski over 7 years ago in reply to Miteshkumar Dalabhai Patel

TI__Genius 10885 points

Hi Mitesh,

I would suspect layout is the primary contributor here, but setting DCDCCTRL_REG[1:0] = 0x00 might be a quick fix to alleviate some radiations.

Do they see an improvement when they clear these two bits?

0 Miteshkumar Dalabhai Patel over 7 years ago in reply to Richard Solarski

TI__Intellectual 1900 points

Hi Richard,

Thanks for response.

Yes, we changed DCDCCTRL_REG[1:0] = 0x00 but didn't observed any change in radiation.

Do you think layout might be the reason? we can ask for layout to customer, so can you be able suggest the changes?

Mitesh

0 Richard Solarski over 7 years ago in reply to Miteshkumar Dalabhai Patel

TI__Genius 10885 points

Hi Mitesh,

First I would check if they are using shielded inductors, as these should help reduce their emissions.

Second, they should try to keep their buck ground connections as short as possible from COUT to CIN, as shown in the figure below.

This reduces the current loop of each buck, reducing the magnetic fields.

The third source could be electric fields from the switch nodes, which can be mitigated by reducing the sizes of the switch nodes, or shielding the switch nodes with ground planes.

All three of these should help reduce their emissions, but they may have to experiment to achieve their target.

0 Miteshkumar Dalabhai Patel over 7 years ago in reply to Richard Solarski

TI__Intellectual 1900 points

Hi Richard,

Thanks for your support. Issue is resolved. They are able to pass CE/RE tests.

We already received orders as well.

Apricate your help.

Regards,

Mitesh

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INT - PMIC TPS65910 Radiation issue