L6563S datasheet(29/42 Pages) STMICROELECTRONICS

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L6563S

Application information

Doc ID 16116 Rev 3

29/42

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

and choose a value Vinx such that Vin2 ≤ Vinx < Vinclamp. This will result in a limitation

of the output voltage range below Vox (it will equal Vox if one chooses Vinx = Vinclamp)

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.

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

Ω.

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

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

maximum specified (0.2 mA):

Figure 40

shows the internal block diagram of the tracking boost function.

Figure 40.

Tracking boost block

clamp

Vin

Vox

Vin

Vox

Vin

⋅

−

⋅

−

Vin

⋅

()

(

)

⎪

⎩

⎪⎪

⎨

⎧

−

⋅

−

⋅

−

⋅

Vin

max

TBO

−

⋅

≤

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