ld7576jps Leadtrend Technology, ld7576jps Datasheet - Page 13

• Manufacturer Part Number: ld7576jps
• Description: Green-mode Pwm Controller With High-voltage Start-up Circuit And Adjustable Olp Delay Time
• Manufacturer: Leadtrend Technology

Leadtrend Technology Corporation
LD7576-DS-03 December 2007
UVLO(on)
UVLO(off)
UVLO(off)
PDR (8V)
UVLO(on)
AC input Voltage
5.0V
5.0V
COMP
VCC
OUT
VCC
COMP
OUT
Switching
Switching
OLP Delay Time
OLP
OLP trip Level
OLP Delay Time
Non-Switching
OLP Counter Reset
Fig. 18
Fig. 17
AC Off
Non- Switching
2nd UVLO(off)
OLP trip Level
Latch Released
AC On ( Recycle)
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Switching
Switching
t
t
t
t
t
t
t
13
OVP (Over Voltage Protection) on Vcc - Auto
Recovery
The maximum V
mostly for 30V. To prevent the V
LD7576X series are implemented with OVP function on Vcc.
Whenever the Vcc voltage is higher than the OVP threshold,
the output gate drive circuit will be shutdown simultaneously
and the switching of the power MOSFET is disabled until the
next UVLO(on).
The Vcc OVP functions of LD7576/76J are auto-recoverable.
If the OVP condition, usually caused by open-loop of
feedback, is not released, the Vcc will tripped the OVP level
again and re-shutdown the output.
hiccup mode. Figure 19 shows its operation.
Otherwise, when the OVP condition is removed, the Vcc
level will be resumed and the output will automatically return
to the normal operation.
OVP (Over Voltage Protection) on Vcc - Latch
mode
As similar behavior like OLP latch-mode, whenever the
voltage on the Vcc pin is higher than the OVP threshold, the
output gate drive circuit will be shutdown simultaneous to
latch off the switching of the power MOSFET. As soon as
the voltage on Vcc pin drops below OVP threshold and
starts AC-recycling again, it will recover to normal operation.
Figure 20 shows its operation.
LD7576/76H/76J/76K
GS
ratings of the power MOSFETs are
Fig. 19
GS
enter fault condition,
The Vcc works in