TLE8386EL

Oscillator and Synchronization

Datasheet

11

Rev. 1.0, 2009-11-30

6

Oscillator and Synchronization

6.1

Description

R_OSC vs. switching frequency

The internal oscillator is used to determine the switching frequency of the boost regulator. The switching frequency

can be selected from 100 kHz to 500 kHz with an external resistor to GND. To set the switching frequency with an

external resistor the following formula can be applied.

In addition, the oscillator is capable of changing from the frequency set by the external resistor to a synchronized

frequency from an external clock source. If an external clock source is provided on the pin FREQ/SYNC, then the

internal oscillator synchronizes to this external clock frequency and the boost regulator switches at the

synchronized frequency. The synchronization frequency capture range is 250 kHz to 500 kHz.

Figure 4

Oscillator and Synchronization Block Diagram and Simplified Application Circuit

Figure 5

Synchronization Timing Diagram

TLE8386

Oscillator

Clock Frequency

Detector

FREQ

/ SYNC

Multiplexer

PWM

Logic

Gate

Driver

SW O

Oscillator_BlkDiag.vsd

[]

()

[]

()

[]

Ω

Ω

×

−

×

×

=

Ω

−

3

1

12

10

5

.

3

10

141

1

s

FREQ

s

f

R

FREQ