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Original question:

TPS50601A-SP: Sync and RT pin configuration

TPS50601A-SP: How close to the External Sync Frequency should the internal oscillator be set to with RT?

Neli08
Prodigy 190 points
Part Number: TPS50601A-SP
Other Parts Discussed in Thread: UC1526A,

Some other devices require the internal oscillator to be lower than the External Sync Frequency, is there a limit on this PWM?  Any issue with just setting the RT value to be as close as possible to the External Sync?

  • 0
    TI__Genius 14540 points

    If I'm understanding you correctly, that is the recommended operating condition, setting the RT resistor to match the external clock.  With this, if there is ever a loss of external clock, the internal oscillator will pickup at nearly the same switching frequency.

    Thanks

    Christian

  • 0 in reply to Christian Yots
    Prodigy 190 points

    So the question is really asking, if there is any adverse effect to the location of the where we should set the RT resistor as compared to the External frequency sync signal.  As an example the UC1526A datasheet states the following:  "The UC1526A can be synchronized to an external logic clock by programming the oscillator to free-run at a frequency 10% slower than the SYNC frequency."

    So this isn't the case for the TPS50601A-sp? 

  • 0 in reply to Neli08
    TI__Genius 14540 points

    Correct, it is different for the TPS50601A-SP.  The device will synchronize to any external clock, within the specified range, regardless of what the RT resistor is.  The recommendation is to set the RT resistor so that the internal oscillator is as close as possible to this external clock in the event of no external clock there is not a huge shift in switching frequency as the internal oscillator starts up.

    Thanks,

    Christian