LT8614 SYNC range

I would like to SYNC the LT8614 to an external 2.0MHz clock

The datasheet mentions that:

The RT resistor should be chosen to set the LT8614 switching frequency equal to or below the lowest synchronization input.

How should I take into account the variation of internal oscillator frequency (as set by Rt) with temperature / unit-unit?

In this case, should I just use 18.2kOhm or would it be beneficial to be a few % higher (i.e. Rt = 1.9MHz nominal)

I've simulated the circuit in LTSpice, but the capture range for SYNC in to RT value appears to be very narrow (<1%)

  • +1
    •  Analog Employees 
    on Sep 15, 2020 11:19 PM 14 days ago

    Hi Laudio,

    The statement of “The RT resistor should be chosen to set the LT8614 switching frequency equal to or below the lowest synchronization input” has already considered the variation of the internal oscillator frequency. 18.2kOhm of Rt should be ok to work with 2MHz sync frequency. Of course, you can set the Rt frequency a little lower, such as 1.9MHz.

    LT8614 LTspice model may not include the SYNC feature.