L6566B STMicroelectronics, L6566B Datasheet - Page 33

• Manufacturer Part Number: L6566B
• Description: IC CTRLR OVP OTP UVLO HV 16SOIC
• Manufacturer: STMicroelectronics

Specifications of L6566B

• Output Isolation: Isolated
• Frequency Range: 10 ~ 300kHz
• Voltage - Input: 8 ~ 23 V
• Power (watts): 750mW
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Output Current: 800 mA
• Output Power: 750 mW
• Input Voltage: 8 V to 23 V
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: SMD/SMT
• Duty Cycle (max): 75 %
• Selectable Multi-mode Operation: fixed frequency or quasi-resonant
• For Use With: 497-6452 - BOARD EVAL FOR L6566B497-6451 - BOARD EVAL FOR L6566B497-6450 - BOARD EVAL FOR L6566B497-6449 - BOARD EVAL FOR L6566A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

L6566B
5.10
This function is useful to implement a latched overtemperature protection very easily by
biasing the pin with a divider from VREF, where the upper resistor is an NTC physically
located close to a heating element like the MOSFET, or the transformer. The DIS pin is a
high impedance input, thus it is prone to pick up noise, which might give origin to undesired
latch-off of the device. It is possible to bypass the pin to ground with a small film capacitor
(e.g. 1-10 nF) to prevent any malfunctioning of this kind.
Figure 20. Operation after latched disable activation: timing diagram
Soft-start and delayed latched shutdown upon overcurrent
At device start-up, a capacitor (C
charged by an internal current generator, I
clamped. During this ramp, the overcurrent setpoint progressively rises from zero to the
value imposed by the voltage on the VFF pin (15, see
latch and voltage feedforward blocks on page 27
gradually, hence controlling the start-up inrush current. The time needed for the overcurrent
setpoint to reach its steady state value, referred to as soft-start time, is approximately:
Equation 12
During the ramp (i.e. until V
are disabled.
Vcc
(pin 16)
AC_OK
Vcc
(pin 8)
(pin 5)
(pin 4)
ON
Vcc
V
Vcc
Vcc
DIS
GD
HVstart
-0.5
restart
4.5V
Vin
Vth
OFF
ON
HV generator is turned on
T
SS
SS
= 2 V) all the functions that monitor the voltage on pin COMP
=
Css
I
SS
SS
) connected between the SS pin (14) and ground is
1
V
csx
Input source is removed here
V (
SS1
VFF
, from zero up to about 2 V where it is
)
); MOSFET’s conduction time increases
=
Css
I
SS
HV generator turn-on is disabled here
1
Section 5.6: PWM comparator, PWM
⎛
⎜ ⎜
⎝
1
−
V
VFF
3
⎞
⎟ ⎟
⎠
Disable latch is reset here
Application information
Restart is quicker
33/51
t
t
t
t
t