HVLED807PF

Device description

Doc ID 023464 Rev 5

23/36

Figure 18.

Voltage control principle: internal schematic

4.7

Voltage feed-forward block

to equation

6 on Section 4.5. Actually, the constant current comparator will be affected by an

higher the foreseen value.

This current overshoot will be equal to:

Equation 8

The previous terms introduce a small error on the calculated average output current set-

point, depending on the input voltage.

The HVLED807PF implements a line feed-forward function, which solves the issue by

introducing an input voltage dependent offset on the current sense signal, in order to adjust

the cycle-by-cycle current limitation.

The internal schematic is shown in

Figure 19.

AM13568v1

Rdmg

Aux

Rf b

From CS pin

CV

To PWM Logic

R

C

COMP

DMG

S/H

DEMAG

LOGIC

EA

2.5V