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TPS54424: Oscillator architecture question

Shinya Sawamoto
Expert 5260 points
Part Number: TPS54424

Hello team,

I have a question about TPS54424 internal oscillator architecture.
The RT/CLK pin is connected to the internal block of "Oscillator with PLL" from the datasheet.
When we use RT mode, the external resistor can control the oscillator frequency.
I thought the resistor would determine the frequency with internal capacitance by making RC oscillator, but the accuracy of 10%(with temperature dependency) is better than I expected.
Is there any nicer technology implemented than I guessed or is there any open material about the internal oscillator architecture? I'm curious about it?

Thanks in advance,
Shinya Sawamoto
TI Japan East area FAE

  • 0
    TI__Mastermind 35115 points
    Hi Shinya-san,

    I do not have the full details of the oscillator architecture but I can say it is similar to a standard RC oscillator. My understanding is the current through the resistor is mirrored internally to charge an internal capacitance to create a ramp and set the fsw. A smaller resistance results in higher current through the RT resistor and higher fsw.

    There is also trimming done in the production test to improve the accuracy of the oscillator.

    Best Regards,
    Anthony
  • 0 in reply to Anthony F
    TI__Expert 5260 points
    Thank you so much, Anthony-san.
    It's helpful answer to me.

    Regards,
    Shinya Sawamoto