L6566B STMicroelectronics, L6566B Datasheet - Page 23

• 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
Figure 10. Operation of ZCD, triggering and oscillator blocks (QR option active)
Arm/Trigger
PWM latch
PWM latch
ON-enable
Oscillator
Reset
blanking
(pin 11)
ramp
Set
(pin 4)
ZCD
time
ZCD
100 mV
GD
50 mV
armed
start-up, at the end of the soft-start phase the output voltage of the converter must meet the
condition:
Equation 4
where Ns is the turn number of the secondary winding, Naux the turn number of the
auxiliary winding and I
The operation described so far under different operating conditions for the converter is
illustrated in the timing diagrams of
If the FF option is selected the operation will be exactly equal to that of a standard current-
mode PWM controller. It will work at a frequency fsw = fosc; both DCM and CCM
transformer's operation are possible, depending on the operating conditions (input voltage
and output load) and on the design of the power stage. The MOSFET is turned on at the
beginning of each oscillator cycle and is turned off as the voltage on the current sense pin
reaches an internal reference set by the line feedforward block. The maximum duty cycle is
limited at 70 % minimum. The signal on the ZCD pin in this case is used only for detecting
feedback loop failures (see
trigger
a) full load
ZCD
Arm/Trigger
ON-enable
PWM latch
PWM latch
Oscillator
Reset
blanking
(pin 11)
Set
ramp
(pin 4)
ZCD
ZCD
time
the maximum pull-up current (130 μ A).
100 mV
GD
50 mV
Section 5.11: OVP block on page 35
Vout >
Figure 10
b) light load
Naux
Ns
.
R
Z
1
I
ZCD
Arm/Trigger
ON-enable
PWM latch
PWM latch
Oscillator
Reset
blanking
(pin 11)
ramp
Set
(pin 4)
ZCD
ZCD
time
100 mV
GD
50 mV
).
Application information
c) start-up
23/51