L6599AF datasheet(14/32 Pages) STMICROELECTRONICS

Part #	L6599AF

Description	Very low temperature improved high voltage resonant controller

PDF	32 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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14 / 32 page

Application information

L6599AF

14/32

DocID028175 Rev 3

Figure 5. Oscillator internal block diagram

The following approximate relationships hold for the minimum and the maximum oscillator

frequency respectively:

Equation 1

After fixing CF in the hundred pF or in the nF (consistently with the maximum source

capability of the RFmin pin and trading this off against the total consumption of the device),

the value of RFmin and RFmax is selected so that the oscillator frequency is able to cover the

entire range needed for regulation, from the minimum value fmin (at minimum input voltage

and maximum load) to the maximum value fmax (at maximum input voltage and minimum

load):

Equation 2

A different selection criterion is given for RFmax in case burst mode operation at no load is

used (see Section 6.2: Operation at no load or very light load).



max

min

max

min

;









;

min

max

min

max

min









L6599AF Datasheet(PDF) 14 Page - STMicroelectronics