TPS65270EVM: TPS65270

ilya feldman

Prodigy 130 points

Part Number: TPS65270EVM
Other Parts Discussed in Thread: TPS65270

Hello

I would like implement a TPS65270 in one of my new development. For it i took a TPS65270EVM for pretesting.

I made preliminary test on TPS65270EVM in one of certification lab in Israel

The TPS65270EVM should be implement in RF devices, therefore I choose mentioned limits:

EMC (EN 301489-3 Class B) and RF RX mode (EN 300 220-1)

Setup at 3m:

for each output VO1 (5VDC) and VO2 (3.3VDC) I connected 3.3 Ω and 5 Ω in order to get 1 A in each output (not worst case).

Vin 16VDC.

The result:

Green line: EN300 220, RX mode 38.2dbuV/m

Gray: -40/-47 dBuV/m EMC EN55032 Class B

What I made wrong ? how can I fix the exception?

over 6 years ago

0 ilya feldman over 6 years ago

Prodigy 130 points

0 Sam(MPAA) Zhang over 6 years ago in reply to ilya feldman

TI__Mastermind 19080 points

Hi,

Are you doing a radiated EMI test?

You may shorten the loading connection like below, and test again.

Regards,

Hao

0 ilya feldman over 6 years ago in reply to Sam(MPAA) Zhang

Prodigy 130 points

Thank you for suggestion- short the loading wires.
Do you suggest to add a EMI Suppression Filters 〉Ferrite Beads , in output or in input? if yes, where and please suggest a part number.

Thank you

0 Zhao Ma over 6 years ago in reply to ilya feldman

TI__Genius 15135 points

Hi, sir

There are 3 suggestions:

1. Suggest to add RC snubber at LX1/LX2 node, set R=2.2ohm, C=470pF, after that, test again.

2. Add bead between power supply and VIN1/2 pin, PN is BLM31KN801SH1L for your reference, after that, test again.

3. Add EMI LC filter between power supply and bead, L= 2.2uH, C= 47uF // 4700pF (MLCC), after that, test again.

0 ilya feldman over 5 years ago in reply to Zhao Ma

Prodigy 130 points

Thank you and sorry for the late response.

At 1 suggestion, you write to add snubber R=2.2ohm and C=470pF. Do i added it at correct place (write in red color)? can you please exactly write i am add it or add a picture (add picture is better)?

At 1 suggestion, you write to add "MI LC filter between power supply and bead, L= 2.2uH, C= 47uF // 4700pF"

do i added correct, (write in red color)? can you please exactly write i am add it or add a picture (add picture is better)?

Thank you a lot!!

0 Zhao Ma over 5 years ago in reply to ilya feldman

TI__Genius 15135 points

Hi, Sir

See below.

0 ilya feldman over 5 years ago in reply to Zhao Ma

Prodigy 130 points

Hello

Last question, please help me understand why you suggest to me add :

Suggest to add RC snubber at LX1/LX2 node, set R=2.2ohm, C=470pF, after that, test again.
Add EMI LC filter between power supply and bead, L= 2.2uH, C= 47uF // 4700pF (MLCC), after that, test again.

I would like learn from your suggestion and not implement it without understanding.
Please explain to me, what your's solution comes to solve and how to calculate the C and L values.

Thank you

Ilya

0 Zhao Ma over 5 years ago in reply to ilya feldman

TI__Genius 15135 points

Hi, Ilya

The RC snubber is to filter the high frequency ring on LXx node.

The LC filter is to further filter high harmonic on LXx node and prevent it conduction to Vin power supply.

The LC value is given based on experience.

For LC calculation, you can refer below application note.

BTW, suggest to use Ecap for C= 47uF.

Power management

Power management forum

TPS65270EVM: TPS65270