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The LT3757 datasheet includes the following schematic:

Schematic

The resistor in the bottom left corner is annotated with a frequency (100kHz). What is the significance of that annotation?

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That resistor sets the frequency of the DC to DC converter, the frequency will be set at 100KHz. Shown below is a table from the datasheet of other values for the Rt resistor that can change the switching frequency.

enter image description here enter image description here
Source: https://www.analog.com/media/en/technical-documentation/data-sheets/3757Afe.pdf

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If you'll notice in the features section of the linked datasheet:

The features section of the linked datasheet. "Programmable Operating Frequency (100kHz to 1MHz) with One External Resistor" is highlighted.

It states that one resistor can be used to set its operating frequency. Evidently, a 140k resistor sets it to its minimum of 100kHz.

On page 11 of the datasheet, Table 1 (shown below) provides resistances to be used for several example frequencies.

A table of frequencies vs resistances, showing 100 kHz corresponds to 140 kΩ.

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  • \$\begingroup\$ You need to provide a source if taking screenshots and provide a link \$\endgroup\$ – Voltage Spike Oct 22 '19 at 18:04
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    \$\begingroup\$ @VoltageSpike I specifically mentioned that these came from the datasheet linked in the question. \$\endgroup\$ – Hearth Oct 22 '19 at 18:05

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