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TMS320F2800157-Q1: INTOSC2 vs INTOSC1, which internal oscillator should be used?

Kita Li
Expert 3555 points

Part Number: TMS320F2800157-Q1

Hi experts,

my customer is now using F2800157 and is using internal oscillator as clock source of F2800157. 

He has the following questions:

1. Which internal oscillator is better for the clock source? The customer is now using INTOSC1.

2. What are the risks if the clock that is not recommended is used?

From TRM I know that INTOSC2 is used to run the boot ROM and can be used as the system clock source for the application. INTOSC1 is a backup clock source that normally only clocks the watchdog timers and missing clock detection circuit (MCD). But I don't know which one would be better.

Thanks!

Best Regards

Kita

  • +1
    TI__Mastermind 43500 points

    Hi Kita,

    Recommendation is to use INTOSC2.  INTOSC1 is default clock to use when MCD is detected and also clocks the watchdog.  The only risk of using INTOSC1 to clock the system  is that if INTOSC1 goes bad, then system will not recover since MCD will not work since system clock and MCD clock are both missing.  If INTOSC2 clocks the system and somehow it goes bad, at least INTOSC1 backup clock will take over preventing the device from hanging up due to absence of clock.

    INTOSC2 is not exclusive to bootrom.  After the bootrom sequence is completed, INTOSC2 can be used for a different purpose like clocking the PLL to generate the required system clock to operate the device.  Hope this is not the reason that the customer is not using INTOSC2 to clock the system.

    Regards,

    Joseph