L6599 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6599' PDF : 36 Pages View PDF
Application information
Figure 28. Power vs frequency curve in an resonant half-bridge
| Z ( f ) | -1
RESONANCE
FREQUENCY
L6599
Steady-state
frequency
f
Initial
frequency
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, RSS and CSS will be selected based on the following relationships:
RSS=
---R-----F----m----i-n----
f--s---t--a---r-t – 1
fmin
Css
=
3-----⋅------1---0----–---3-
RSS
where fstart is recommended to be at least 4 times fmin. The proposed criterion for CSS 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 31 to see some
significant signals during the soft-start phase.
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