STMicroelectronics EVAL BOARD FOR L6563 EVL6563H-250W EVL6563H-250W Fiche De Données

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Doc ID 16047 Rev 3

V(TBO)/RT, that is internally 1:1 mirrored and sunk from pin INV (#1) input of the L6563H's 
error amplifier. In this way, when the mains voltage increases the voltage at TBO pin 
increases as well and so does the current flowing through the resistor connected between 
TBO and GND. Then a larger current is sunk by INV pin and the output voltage of the PFC 
pre-regulator is forced to get higher. Obviously, the output voltage moves in the opposite 
direction if the input voltage decreases. 

To avoid undesired output voltage rise should the mains voltage exceed the maximum 
specified value, the voltage at the TBO pin is clamped at 3V. By properly selecting the 
multiplier bias it is possible to set the maximum input voltage above which input-to-output 
tracking ends and the output voltage becomes constant. If this function is not used, leave 
the pin open: the device regulates a fixed output voltage.

Starting from the following data:

●

Vin

1

 = minimum specified input RMS voltage;

●

Vin

2

 = maximum specified input RMS voltage;

●

Vo

1

 = regulated output voltage @ Vin = Vin

1

;

●

Vo

2

 = regulated output voltage @ Vin = Vin

2

;

●

Vox = absolute maximum limit for the regulated output voltage;

to set the output voltage at the desired values use the following design procedure:

1.

Determine the input RMS voltage Vinclamp that produces Vo = Vox: 

and choose a value Vin

x

 such that Vin

2

 

≤ 

Vinx < Vinclamp. This results in a limitation of 

the output voltage range below Vox (it is equal Vox if one chooses Vin

x

 = Vin

clamp

)

2. 

Determine the divider ratio of the MULT pin (#3) bias:

and check that at minimum mains voltage Vin1 the peak voltage on pin 3 is greater than 
0.65 V. 

3. 

Determine R1, the upper resistor of the output divider, for instance 3 M

Ω.

4. 

Calculate the lower resistor R2 of the output divider and the adjustment resistor RT:

5. 

Check that the maximum current sourced by the TBO pin (#6) does not exceed the 
maximum specified (0.2 mA): 

 shows the internal block diagram of the tracking boost function.

1

1

2

2

2

1

2

1

clamp

Vin

Vo

Vo

Vo

Vox

Vin

Vo

Vo

Vo

Vox

Vin

⋅

−

−

−

⋅

−

−

=

x

Vin

2

3

k

⋅

=

(

)

(

)

⎪

⎪

⎩

⎪⎪

⎨

⎧

−

−

⋅

⋅

⋅

=

⋅

−

−

⋅

−

−

⋅

⋅

=

1

2

1

2

T

1

2

2

1

1

2

Vo

Vo

Vin

Vin

1

R

k

2

R

Vin

5

.

2

Vo

Vin

5

.

2

Vo

Vin

Vin

1

R

5

.

2

2

R

3

T

max

TBO

10

2

.

0

R

3

I

−

⋅

≤

=