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Original question:

TPS50601A-SP: What happens when external SYNC is lost on an TPS50601A-SP?

TPS50601A-SP: Sync and RT pin configuration

Neli08
Prodigy 190 points
Part Number: TPS50601A-SP

In the spec, there are 3 conditions of operation:  1) Master, 2) Internal Oscillator and 3) External Synchronization.  I intend to use the option 3, External Sync. 

I have 3 questions:

1) I want to know what happens during start up, should the SYNC pin be held Low, High, or Open? 

2) What happens if the SYNC pin is grounded or held high?

3) From another similar issue on the forum if you lose the SYNC signal, the PWM will adopt the frequency set by the RT resistor.  It will not go to 500KHz, correct?

  • 0
    TI__Genius 14540 points

    HI,

    1) I want to know what happens during start up, should the SYNC pin be held Low, High, or Open? 

    [CY] The device is always looking for an external clock signal on the SYNC pin when RT is installed.  If none is detected for 20us, i.e. left floating, the SYNC pin becomes an output clock at 180 degrees phase to the internal oscillator.  If the SYNC pin is grounded or held high, I do not know the effect on the output clock driver as this is not a recommended operating condition.

    2) What happens if the SYNC pin is grounded or held high?

    [CY]  see above

    3) From another similar issue on the forum if you lose the SYNC signal, the PWM will adopt the frequency set by the RT resistor.  It will not go to 500KHz, correct?

    [CY] That is correct.  The internal oscillator will adjust to the frequency determined by the RT resistor.

    Thanks

    Christian