• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 275 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS62824: || RE CE EMC TESTING SUPPORT || BSMA_ACMH

Hemal Patel
Intellectual 345 points
Part Number: TPS62824
Other Parts Discussed in Thread: TPS628301

Tool/software:

We have completed the first level of RE CE testing of this AM6254 based EVT Board [ACM Device]. We got the negative result of these RE and CE tests. And as per report analysis we suspect that below parts can be the reason for this test failure.

1. Switcher 2V5
MPN:- TPS62824DMQ
Mfr:- Texas Instrument
Sch Ref des:- U8
Test setup:-
1. CE Test Results
--> LAN1 & LAN2 CE Test POE SUPPLY MOE
Test Standard Test Mode Result Remarks
LAN1 [POE SUPPLY]
Limit: CLASS- B
Frequency: 150 KHz to 30 MHz
--> POE SUPPLY Mode
Interface:- LAN1, LAN2, USB, eMMC, RTC, Temp, IR
 FAIL LAN1_CE_POE_SUPPLY_WITH_COMN-14092024
LAN2 [POE SUPPLY] FAIL LAN2_CE_POE_SUPPLY_WITH_COMN-14092024

2. RE Test Results
-->RE Test POE SUPPLY MOE
Test Standard Test Mode Result Remarks
RE [POE SUPPLY]
 Limit: CLASS- B
Frequency: 30mhz To 1ghz
--> POE SUPPLY Mode
Interface:- LAN1, LAN2, USB, eMMC, RTC, Temp, IR
 FAIL RE_POE SUPPLY RE-30 TO 1ghz -14.09.2024
Limit: CLASS- B
Frequency: 1ghz to 6ghz		 PASS RE_POE SUPPLY_RE-1 TO 6ghz -14.09.2024

We have attached the RE & CE report and schematic design of our ACM Boards so please check and share your suggestions like what changes we should make for these components to pass this RE & CE test.

2275.LAN1_CE_POE_SUPPLY_WITH_COMN-14092024.Pdf2275.LAN2_CE_POE_SUPPLY_WITH_COMN-14092024.Pdf5808.RE_POE SUPPLY RE-30 TO 1ghz -14.09.2024.Pdf

  • 0
    Intellectual 345 points

    Hello TI Expert,

    we are currently stuck at this point so help to provide resolution ASAP.

  • 0 in reply to Hemal Patel
    TI__Mastermind 21560 points

    Hi Hemal,

    Can you kindly share your layout file as well? The layout of the IC also has a big influence on EMI. You can send it to v-john@ti.com. 

    Here are some questions/suggestions from my side:

    • To reduce EMI, a good layout and filtering techniques can help. It is important to have vias close the IC GND pin as well as the GND pad of all input and output caps. The second layer of your PCB (just below the DC-DC) should be complete GND plane. Input and output caps should be placed as close as possible to the IC. If possible, a decoupling cap (~1nF) in 0402 case size can be added to the input and placed as close as possible to IC VIN and GND pins. On the input side a damped pi filter (using ferrite bead) can also be added to prevent noise from propagating further down this rail. A second LC filter (using ferrite bead) can also be added on the output to localize the noise.
    • What is the difference between LAN1 and LAN2 CE tests? There is a peak at around 250KHz in LAN1 report. This is pretty low frequency. Can you tell me what is the load on the TPS62824 in LAN1 and LAN2 CE tests? 
    • We have a new low EMI device TPS628301 that helps reduce higher frequency (> 450MHz) emissions. You will still have to add the filtering I mentioned in the first point to take care of the lower frequency noise. Using a 1uH inductor will be beneficial to reduce switching ripple with this device.

    Best regards,

    Varun