• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 252 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.

AMC1303M2520: Radiated emission measurement for products using AMC1303

Conor
Guru 13035 points
Part Number: AMC1303M2520


Tool/software:

Hi,

Q1.
When measuring radiated emission for products using AMC1303, the noise emitted from this IC is large, so I would like some advice on noise reduction measures.

Q2.
I am considering the following two points.
　-Adding ferrite beads to the power line
　-Adding an RC filter (100Ω, 33pF) to the output (MCLK, MDAT)

Regarding adding ferrite beads to the power line, is it recommended to put this ferrite bead between the IC and the 0.1uF ceramic capacitor (in the order IC-ferrite beads-0.1uF-2.2uF-VCC)? Or is it recommended to put it between the VCC and the 2.2uF ceramic capacitor (in the order IC-0.1uF-2.2uF-ferrite beads-VCC)?

Thanks,

Conor

  • +1
    TI__Guru 56532 points

    Hi Conor,

    Does the customer have RE plots that can be shared showing the current performance? 

    How about schematic or layout?

    In general, adding ferrite beads to the power lines can be helpful, but the RE performance will be largely impacted by the layout design as it is functionally the antenna that the emissions radiate from. So where exactly to place this bead can have a very large impact on the RE performance. In general it is best to keep the decoupling capacitors as close as possible to the VCC pin, then the ferrite bead on the other side of the decoupling capacitors. VCC -> 2.2uF -> FB. Selection of the ferrite bead will depend on the RE measurement over frequency. 

    For clock and data: it is best to add an RC filter with the resistor close to the source and capacitor near the destination. Depending on the impedance of the MCLK and MDAT traces, the RC filter values can be fine-tuned. If using a multi-layer PCB. GND can be used for the top and bottom layer to act as a shield, while MCLK and MDAT can be routed on the internal layers. 

  • 0 in reply to Alexander Smith
    Guru 13035 points

    Hi Alexander,

    Thanks for your reply!
    Can you allow me to private message you so I can share the schematic/layout info?

    Thanks,

    Conor