LD7576GS Просмотр технического описания (PDF) - Unspecified

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производитель

LD7576GS

Green-Mode PWM Controller

Unspecified 

VCC

UVLO(on)

UVLO(off)

OLP

2nd UVLO(off)

OLP Counter Reset

t

COMP

OLP Delay Time

5.0V

OLP trip Level

t

OUT

Switching

Non-Switching

COMP

Fig. 17

OLP Delay Time

Switching

t

5.0V

OLP trip Level

t

VCC

UVLO(on)

UVLO( off)

PDR(8V)

AC input Voltage

Latch Released

t

AC Off

AC On( Recycle)

t

LD7576/76H/76J/76K

OVP (Over Voltage Protection) on Vcc - Auto

Recovery

The maximum VGS ratings of the power MOSFETs are

mostly for 30V. To prevent the VGS enter fault condition,

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. The Vcc works in

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.

OUT

Switching

Non- Switching

Fig. 18

Switching

t

Fig. 19

Leadtrend Technology Corporation

LD7576-DS-03 December 2007

13

www.leadtrend.com.tw

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