TLD5097EL_15 Datasheet, PDF (14/41 Pages) Infineon Technologies AG – Multitopology LITIX Power DC/DC Controller IC

Infineon® LITIX™ Power
TLD5097EL
Oscillator and Synchronisation
6
Oscillator and Synchronisation
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.
( ) R _FREQ
=
1
−
(141
⋅ 10
−12
⎡
⎢⎣
s
Ω
⎤
⎥⎦
)
⋅
⎜⎛
⎝
f _FREQ
⎡
⎢⎣
1
s
⎤
⎥⎦
⎟⎞
⎠
3 .5 ⋅10 ³ [Ω ] [Ω ]
(6.1)
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.
V_CLK
FREQ / SYNC
11
R_FREQ
Oscillator
Clock Frequency
Detector
Multiplexer
PWM
Logic
Gate
Driver
2 SWO
Figure 6-1 Oscillator and Synchronization Block Diagram and Simplified Application Circuit
V_SYNC
V_SYNC,H
V_SYNC,L
T_SYNC = 1 / f_SYNC
t_SYNC,PWH
t
Figure 6-2 Synchronization Timing Diagram
Data Sheet
14
Revision 1.0
2015-03-12