• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 98 subscribers
  • Views 352 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.

RTOS/AM4377: ProfiNET PHY oscillator clock

Steven Liu1
Expert 4455 points
Part Number: AM4377
Other Parts Discussed in Thread: AMIC120, AMIC110

Tool/software: TI-RTOS

Hi Team,

My customer decided to use the AMIC120 for the ProfiNET solution, as AM4377 shares the same design, so I marked this question with AM4377.

By checking the design of the AMIC110 ICE EVM. It was found that two 25MHz OSC are used for each ProfiNET port's PHY. 

As the project is really cost-sensitive, they'd like to ask whether the two 25MHz OSC could be replaced by the clock output of the MPU? This could save the cost of the two OSCs.  

If not, is it possbile to have the two ProfiNET port PHYs share the same 25MHz OSC, which can save them the cost of one OSC? 

  • 0
    TI__Guru**** 393215 points
    Hi,

    Section 6.2.4 of the AMIC110 Datasheet Rev. B states:

    "The AMIC110 CLKOUT1 and CLKOUT2 clock outputs should not be used as a synchronous clock for any of the peripheral interfaces because they were not timing closed to any other signals. These clock outputs also were not designed to source any time critical external circuits that require a low jitter reference clock. The jitter performance of these outputs is unpredictable due to complex combinations of many system variables. For example, CLKOUT2 may be sourced from several PLLs with each PLL supporting many configurations that yield different jitter performance. There are also other unpredictable contributors to jitter performance such as application specific noise or crosstalk into the clock circuits. Therefore, there are no plans to specify jitter performance for these outputs."

    You can use an external 25-MHz ±50 ppm CMOS-level oscillator for clocking both PHY's.