• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 98 subscribers
  • Views 1179 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.

About AM335x Touch Screen Controller

g.f.
Guru 15520 points

Hi,

I have question about AM335x TSC_ADC_SS(Touchscreen Controller and A/D coverter subsystem).

At our customer they did electrostatic noise test.
For result, touchpanel stopped operating but other peripheral
such as LCD controller and GPMC are still operating.

They have following question:
1. Is it possible that only TSC_ADC_SS stop operating by noise?
   For example, is it possible that TSC_ADC_SS stop operating
   if VREFN/P pin becomes unusual voltage for a moment?

2. Does ADC power pin "VDDA_ADC" need special process?
   For example, does it need external filter circuit?

3. Is there any information about the cause by which only TSC_ADC_SS stops?

best regards,
g.f.

  • 0
    TI__Guru**** 393215 points

    Hi g.f.

    Yes, there have been one or two reports about this happening. On your questions:

    1. VREF pins voltage should not exceed specs at any time (Table 5-16 in AM335X Datasheet Rev. G).
    2. There are ferrite beads on VDDA_ADC and VSSA_ADC in all TI reference designs. ADC ground is separate from common ground.
    3. I don't have information about this.
    Does your customer have TVS on the TSC lines? If not, I suggest they try to place suppressors with low capacitance (TVS suitable for USB lines will probably work well).
  • 0 in reply to Biser Gatchev-XID
    Guru 15520 points

    Hi Biser,

    Thank you for the reply.

    I understood.

    I don't know my customer are using suppressor on the TSC lines.
    If they are not using it, I will suggest to use it.
    Thank you so much.

    best regards,
    g.f.