L6668 STMicroelectronics, L6668 Datasheet - Page 18

• Manufacturer Part Number: L6668
• Description: IC CTRLR PWM PROG CM HV 16SOIC
• Manufacturer: STMicroelectronics

Specifications of L6668

• Output Isolation: Isolated
• Frequency Range: 93 ~ 107kHz
• Voltage - Input: 9.4 ~ 22 V
• Power (watts): 750mW
• Operating Temperature: -25°C ~ 150°C
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Number Of Outputs: 1
• Duty Cycle (max): 75 %
• Output Current: 800 mA
• Mounting Style: SMD/SMT
• Switching Frequency: 105 KHz
• Maximum Operating Temperature: + 150 C
• Fall Time: 30 ns
• Minimum Operating Temperature: - 25 C
• Rise Time: 55 ns
• Synchronous Pin: No
• Topology: Flyback
• Load-dependent Current-mode Control: FIXED-FREQUENCY (HEAVY LOAD), FREQUENCY FOLDBACK (LIGHT LOAD), BURST-MODE (NO-LOAD)
• For Use With: 497-6389 - BOARD EVAL USING L6668 & STSR30497-5499 - EVAL BOARD FOR L6668
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

L6668
Figure 43 shows a timing diagram where the PFC_STOP function operation is illustrated under different
operating conditions.
Figure 42. How the L6668 can switch off a PFC controller at light load
Figure 43. Operation of PFC_STOP function
Figure 44. Operation after DIS pin activation: timing diagram
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Vcc
Vcc
PFC_STOP
Vcc
Vcc
ON
ON
Vcc
Vcc
V
V
Vcc
Vcc
OUT
OUT
HVstart
HVstart
Vcc
Vcc
DIS
DIS
-0.5
-0.5
Vin
Vin
2.2V
2.2V
OFF
OFF
COMP
rest
rest
ON
ON
Vcc
Drive
Gate
OUT
PFC
Vcc
Vcc
OFF
L6668
L6668
ON
Vcc
Vcc
16
16
Start-up
14
14
PFC_STOP
PFC_STOP
HV generator is turned on
HV generator is turned on
Full-load
10 k Ω
10 k Ω
2.2 k Ω
2.2 k Ω
BC557
BC557
2.2V
Input source is removed here
Input source is removed here
8.2 V
8.2 V
Light-load
HV generator is disabled here
HV generator is disabled here
2.7V
Disable latch is reset here
Disable latch is reset here
controller
controller
Vcc
Vcc
PFC
PFC
Full-load
t
t
t
t
t
t
t
t
t
t
t
t
t