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Oscillator Disable for TMS570LS3137

rajeeva gk37
Prodigy 120 points
Other Parts Discussed in Thread: TMS570LS3137

Hi,

If we are using external oscillator source of 16MHz, can we disable the internal oscillator circuit of TMS570LS3137?

The present hardware configuration is as follows:

pin OSCIN  is connected with 3.3V 16MHz Squarewave TCXO 

pin OSCOUT - is floating

Pin KELVIN_GND -- is connected to GND.

with regards

Rajeeva G.K. 

  • 0
    TI__Mastermind 22715 points
    Rajeeva,

    There are two internal clcoks: HFLPO (10MHz) and LFLPO (32KHz). The system will automatically switched to HFLPO if the external clock fails. I would recommend to keep all clock domains on.

    Thanks and regards,

    Zhaohong
  • 0 in reply to Zhaohong Zhang
    Prodigy 120 points
    Zhaohong,

    Thanks.

    We are not planning to disable, HFLPO or LFLPO.
    Since we are providing external clock source, do we need to keep internal OSCILLATOR circuit enabled?
    Refer: TMS570LS31x/21x 16/32-Bit RISC Flash Microcontroller, Technical Reference Manual, SPNU499B.pdf Section 10.3 and its sub-sections.

    My second question, As per section 10.3.3,
    "The oscillator disable signal places the oscillator into a low power state, disconnects the feedback (bias) resistor between OSCIN and OSCOUT, and OSCIN is grounded".
    If the case, Since External Clock Source is connected to OSCIN pin, if we disable Oscillator as per 10.3.3, OSCIN is grounded, do the processor still clocked with external Clock? Or Processor will be clocked with LPOs?
  • 0 in reply to rajeeva gk37
    TI__Mastermind 22715 points
    I think that I got what you meant. You will need to keep the internal Oscillator circuit enabled to use the external clock source not matter you are going to drive it or not.

    Thanks and regards,

    Zhaohong