L6566B STMicroelectronics, L6566B Datasheet - Page 36

• 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
Note:
36/51
Figure 23. OVP function: timing diagram
The value of R
capability of the internal clamp:
Equation 14
where Vin
winding. See
page 21
To reduce sensitivity to noise and prevent the latch from being erroneously activated, first
the OVP comparator is active only for a small time window (typically, 0.5 µs) starting 2 µs
after MOSFET’s turn-off, to reject the voltage spike associated to the positive-going edges
of the voltage across the auxiliary winding Vaux; second, to stop the L6566B the OVP
comparator must be triggered for four consecutive switching cycles. A counter, which is
reset every time the OVP comparator is not triggered in one switching cycle, is provided to
this purpose.
Figure 22 on page 35
Figure 23
To use the OVP function effectively, i.e. to ensure that the OVP comparator will be always
interrogated during MOSFET’s OFF-time, the duty cycle D under open-loop conditions must
fulfill the following inequality:
COUNTER
COUNTER
STATUS
RESET
STROBE
(pin 11)
(pin 4)
FAULT
COUT
ZCD
GD
Vaux
5V
OVP
0
for additional details.
0
max
illustrate the operation.
NORMAL OPERATION
Section 5.2: Zero current detection and triggering block; oscillator block on
is the maximum dc input voltage and Ns the turn number of the primary
2 µs
Z1
0
will be such that the current sourced by the ZCD pin be within the rated
shows the internal block diagram, while the timing diagrams in
0.5 µs
0
0 → 1
TEMPORARY DISTURBANCE
R
Z
1
≥
1 → 2
3
⋅
10
1
−
2 → 0
3
Naux
Np
0
Vin
max
0 → 1
FEEDBACK LOOP FAILURE
1 → 2
2 → 3
3 → 4
L6566B
t
t
t
t
t
t
t
t
t