L6566B STMicroelectronics, L6566B Datasheet - Page 38

• 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

Application information
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Figure 25. Brownout protection: internal block diagram and timing diagram
The brownout comparator is provided with current hysteresis in addition to voltage
hysteresis: an internal 15 µA current sink is ON as long as the voltage applied on the
AC_OK pin is such that the AC_FAIL signal is high. This approach provides an additional
degree of freedom: it is possible to set the ON threshold and the OFF threshold separately
by properly choosing the resistors of the external divider (see below). With just voltage
hysteresis, instead, fixing one threshold automatically fixes the other one depending on the
built-in hysteresis of the comparator.
With reference to
(Vsen
Equation 16
which, solved for R
Equation 17
Sensed
R
R
voltage
H
L
AC_OK
ON
) and OFF (Vsen
16
L6566B
Vsen
R
15 µA
H
ON
Figure 25
=
R
H
0.485V
0.45V
Vsen
H
−
and R
. 0
485
OFF
ON
Vcc
+
-
L
, the following relationships can be established for the ON
, yield:
−
15
) thresholds of the sensed voltage:
=
5
. 1
15
⋅
078
10
⋅
AC_FAIL
10
−
6
⋅
Vsen
−
6
+
. 0
OFF
R
485
Sensed voltage
L
;
Vsen
VAC_OK
Vsen
(pin 16)
AC_FAIL
(pin 5)
(pin 4)
15 µA
Vcc
GD
Vout
OFF
I
HYS
ON
R
L
0.485V
=
Vsen
R
H
Vsen
OFF
R
H
−
OFF
. 0
. 0
45
45
−
. 0
=
45
. 0
R
45
L
L6566B
0.45V
t
t
t
t
t
t
t