LD7750AGR Просмотр технического описания (PDF) - Unspecified

Номер в каталоге

Компоненты Описание

производитель

LD7750AGR

High Voltage Green-Mode PWM Controller with Over Temperature Protection

Unspecified 

Fig. 15

Fig. 16

LD7750A

Internal Slope Compensation

Stability is crucial for current mode control when it

operates at more than 50% of duty-cycle. To stabilize the

control loop, the slope compensation is required in the

traditional UC384X design by injecting the ramp signal

from the RT/CT pin through a coupling capacitor. In the

LD7750A, the internal slope compensation circuit has

been implemented to simplify the external circuit design.

On/Off Control

The LD7750A can be turned off by pulling COMP pin to

lower than 2.0V. The gate output pin of LD7750A will be

disabled immediately under such condition. The off-mode

can be released when the pull-low signal is removed.

Green-Mode Operation

By using the green-mode control, the switching frequency

can be reduced under the light load condition. This feature

helps to improve the efficiency in light load conditions.

The green-mode control is Leadtrend Technology’s own

IP.

Over Load Protection (OLP) - Auto

Recovery

To protect the circuit from damage caused by overload

condition or output short condition, a smart OLP function

is implemented in the LD7750A for it. The OLP function in

LD7750A is an auto-recovery type protection. Fig. 17

shows the waveforms of the OLP operation. Under such

fault condition, the feedback system will force the voltage

loop toward saturation and thus pull the voltage on COMP

pin (VCOMP) to high. Whenever the VCOMP trips the

OLP threshold of 5.0V and stays for over 64mS, the

protection will be activated to turn off the gate output and

to shutdown the switching of power circuit. The 64mS

delay time is to prevent the false-trigger during the

power-on and turn-off transient.

Leadtrend Technology Corporation

LD7750A-DS-00 June 2010

11

www.leadtrend.com.tw

Share Link: