Datasheet

L6585DE Application information
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5.2 PFC section
5.2.1 TM PFC operation
The PFC stage contains all the features needed to implement a transition mode PFC
controller.
Figure 4. PFC section
The control loop can be implemented thanks to the high performance error amplifier and the
very precise internal voltage reference that fixes the non-inverting input of the E/A to 2.52 V
± 2 %.
The control loop reacts in order to bring the inverting input to the same voltage. Connecting
the high voltage rail to INV pin, by means of a voltage divider, the output voltage will be
easily set.
The output of the E/A can be used in order to compensate the control loop with an RC
network or, more often, with a simple capacitor connected between INV and COMP pin.
The output voltage of the E/A is also fed to the multiplier. This block multiplies the waveform
present at the MULT pin by the output of the E/A. The resulting voltage will be used as the
threshold for the current sense input. An internal clamp limits the threshold to a maximum
value equal to 1 V.
In Figure 5 the characteristic curves of the multiplier are reported.
Figure 5. Multiplier