Datasheet

Application information L6563 - L6563A
24/39
to set the output voltage at the desired values use the following design procedure:
1. Determine the input RMS voltage Vin
clamp
that produces Vo = Vox:
Equation 6
and choose a value Vin
x
such that Vin
2
= Vin
x
< Vin
clamp
. This will result in a limitation of the
output voltage range below Vox (it will equal Vox if one chooses Vin
x
= Vin
clamp
)
2. Determine the divider ratio of the MULT pin (pin 3) bias:
Equation 7
and check that at minimum mains voltage Vin
1
the peak voltage on pin 3 is greater than
0.65V.
3. Determine R1, the upper resistor of the output divider:
Equation 8
4. Calculate the lower resistor R
2
of the output divider and the adjustment resistor R
T
:
Equation 9
Vin
clamp
Vox Vo
1
–
Vo
2
Vo
1
–
---------------------------
Vin
2
Vox Vo
2
–
Vo
2
Vo
1
–
---------------------------
Vin
1
⋅–⋅=
k
3
2Vin
x
⋅
-----------------------=
R1
Vo∆
20
-----------
10
6
⋅=
R2 2.5 R1
Vin
2
Vin
1
–
Vo
1
2.5–()Vin
2
Vo
2
2.5–()Vin
1
⋅–⋅
--------------------------------------------------------------------------------------------------
⋅⋅=
R
T
2kR1
Vin
2
Vin
1
–
Vo
2
Vo
1
–
------------------------------
⋅⋅ ⋅=