l6599atn STMicroelectronics, l6599atn Datasheet - Page 22

• Manufacturer Part Number: l6599atn
• Description: Improved High-voltage Resonant Controller
• Manufacturer: STMicroelectronics

Application information
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Figure 12. Soft-start and delayed shutdown upon overcurrent timing diagram
This function is achieved with pin 2 (DELAY), by means of a capacitor C
resistor R
OCP comparator, in addition to discharging C
sources 150 µA from the DELAY pin and charges C
the OCP comparator and the internal current source are repeatedly activated and C
charged with an average current that depends essentially on the time constant of the current
sense filtering circuit, on C
due to R
much longer.
This operation continues until the voltage on C
There is not a simple relationship that links T
determine C
order of 100 ms.
Once C
continuously regardless of the OCP comparator’s output, and the 150 µA current source is
continuously on, until the voltage on C
Equation 9
with T
frequency close to f
resonant circuit. As the voltage on C
PFC_STOP pin is pulled low. Also, the internal generator is turned off, so that C
slowly discharged by R
which takes:
Equation 10
MP
Delay
Delay
expressed in ms and C
Delay
Delay
is charged at 2 V the internal switch that discharges C
can be neglected, considering that the associated time constant is typically
connected to ground. As the voltage on the ISEN pin exceeds 0.8 V the first
experimentally. As a rough indication, with C
start
Delay
(see
T
STOP
SS
. The IC restarts when the voltage on C
Section 6.3: Soft-start
and the characteristics of the resonant circuit. The discharge
=
Doc ID 15534 Rev 1
R
Delay
Delay
Delay
in µF. During this time, the L6599AT runs at a
T
Delay
C
MP
Delay
is 3.5 V, the L6599AT stops switching and the
=
reaches 3.5 V. This phase lasts:
10
SH
ln
SS
Delay
⋅
3
0
, turns on an internal current generator that
C
to C
5 .
3 .
Delay
≈
) to minimize the energy inside the
reaches 2 V, which defines the T
Delay
2
Delay
5 .
R
. During an overload/short-circuit
, thus it is more practical to
Delay
C
Delay
Delay
SS
Delay
= 1 µF, T
is forced low
Delay
is less than 0.3 V,
SH
and a parallel
is in the
Delay
L6599AT
SH
Delay
is now
time.
is