Datasheet

Application information L6599
22/36
Figure 29. Power vs frequency curve in an resonant half-bridge
As a result, the average input current will smoothly increase, without the peaking that occurs
with linear frequency sweep, and the output voltage will reach the regulated value with
almost no overshoot.
Typically, R
SS
and C
SS
will be selected based on the following relationships:
where f
start
is recommended to be at least 4 times f
min
. The proposed criterion for C
SS
is
quite empirical and is a compromise between an effective soft-start action and an effective
OCP (see next section). Please refer to the timing diagram of Figure 32 to see some
significant signals during the soft-start phase.
RESONANCE
FREQUENCY
f
| Z ( f ) |
-1
Initial
frequency
Steady-state
frequency
R
SS
RF
min
f
start
f
min
------------ 1–
--------------------- -=
C
ss
310
3–
⋅
R
SS
-------------------=