L6567 STMicroelectronics, L6567 Datasheet - Page 9

• Manufacturer Part Number: L6567
• Description: HIGH VOLTAGE DRIVER FOR CFL
• Manufacturer: STMicroelectronics

Other easy formulas fit rather well:
T
T
As far as df/dt is concerned, there are no easy formulas that fit the relation between C
and discharged by three different currents that are derived from different mirroring ratios by the current flowing
on R
proportional to df/dt.
The values obtained in the testing conditions (C
during preheating and working conditions the typical frequency increase is ~ 20KHz/ms, the typical decrease is
~-10Khz/ms;
During ignition the frequency variation is ~ -200Hz/ms.
If slower variations are needed, CI has to be increased.
Due to these tight relationships, it is recommended to follow a precise procedure: first R
looking at startup current needs and dissipation problems. Then the feed forward frequency range has to be
determined, and so C
Given a certain C
The other external parameters (R
single circuit parameters.
DT
PRE
REF
46.75 · 10
224 · C
. The voltage variations on C
P
^-12
· R
F
, R
REF
· R
REF
F
REF
is set.
is set in order to fix F
SHUNT
I
are proportional to the current that charges C
and C
MIN
I
) can be chosen at the end because they are just related to a
I
= 100nF) are:
. Now C
P
can be chosed to set the desired T
F
, R
F
, that is to say they are
F
, and C
HV
has to be chosen
PRE
I
. C
I
and T
is charged
L6567
IGN
9/15
.