Data Sheet

LT8350S

analog.com

Rev. A

25 of 36

APPLICATIONS INFORMATION

This section serves as a guideline for selecting external components for typical applications. See the Simplified

Application Diagram for more details. Unless otherwise specified, the examples and equations in this section assume

continuous conduction mode.

Switching Frequency Selection

The LT8350S uses a constant frequency control scheme between 200kHz and 2MHz. The selection of the switching

frequency is a trade-off between efficiency and component size. Low-frequency operation improves efficiency by

reducing MOSFET switching losses but requires larger inductor and capacitor values. Consider operating at lower

frequencies for high-power applications to minimize MOSFET heating from switching losses. Consider operating at

higher frequencies for low-power applications to minimize the total solution size. In addition, the specific application

also plays an important role in switching frequency selection. In a noise-sensitive system, the switching frequency is

usually selected to keep the switching noise out of a sensitive frequency band.

Switching Frequency Setting

The internal oscillator can set the LT8350S's switching frequency. With the SYNC/MODE pin pulled to ground, a

resistor from the RT pin to ground sets the switching frequency. Table 7 shows RT resistor values for common

switching frequencies.

Table 7. Switching Frequency vs RT Value (1% Resistor)

FOSC (kHz)

RT (kΩ)

200

249

400

124

600

78.7

800

56.2

1000

43.2

1200

33.2

1400

26.1

1600

21.5

1800

17.4

2000

14.3