Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

  • State Resolved
  • Replies 2 replies
  • Subscribers 100 subscribers
  • Views 238 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

[FAQ] AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 Custom board hardware design – Queries regarding MCU_OSC0 Start-up Time

Kallikuppa Sreenivasa
Guru**** 155569 points
Part Number: AM625

Tool/software:

Hi TI Experts,

 I have a question about "Figure 7-16. MCU_OSC0 Start-up Time" from the datasheet. Here it looks like that MCU_OSC0 is only allowed to start when VDD_CORE is ramping. In reality the oscillation starts already with VDDS_OSC0, while VDD_CORE is still disabled. 

I assume that this is OK and not causing any problems?! But if this is the case, why is the Start-up Time ts shown relative to VDD_CORE stable? Shouldn't it be related to VDDS_OSC0 stable?

 

  • 0
    TI__Guru**** 155569 points

    Hi Board designers, 

    Refer below inputs for the queries related to the MCU_OSC0 Start-up Time received from our device expert Paul Eaves.

    The oscillator is powered from VDDS_OSC0. So it may power-up and begin oscillation as soon as VDDS_OSC0 is applied. However, the oscillator has a few control registers which are powered by the VDD_CORE domain. So there is a chance the oscillator may not start until the VDD_CORE is valid. 

    Regards,

    Sreenivasa

  • +1 in reply to Kallikuppa Sreenivasa
    TI__Guru**** 155569 points

    Hi Board designers, 

    Additional inputs received from our device expert Paul Eaves.:

    The data sheet specifies the Start-up Time of MCU_OSC0, but is this a typical or maximum value?

    The value defined it the datasheet is a typical value. The max value depends on the crystal circuit components and PCB layout, so it is not possible for TI to define a maximum value. There is a good chance the start-up time will be less than 9ms if you select crystal circuit components that are compliant to the datasheet values and follow the recommended PCB layout.

    Regards,

    Sreenivasa