LR5920 Datasheet, PDF (1/12 Pages) Leshan Radio Company – High Performance Current Mode PWM Switching Power Supply Controller

LR5920
High Performance Current Mode PWM Switching Power Supply Controller
DESCRIPTION
The LR5920 is a current mode PWM switching power supply
controller that specifically designed for AC/DC converter with high
perfo rmance versus cost ratio. It provides continuo us output power up to
12W in the bro ad voltage range o f 8 5V – 265V.Its o ptimized and highly
reaso nable circuit design has made it po ssible to minimize the total cost
of the pro duct. This power supply co ntroller could be used in typical
flyback circuit topology to constitute simp le AC/DC converter. The
internal initiating circuit of 5920 has been designed with a uniq ue means
of current sink to complete the startup using the amplifying function of the
power switching tube. This will significantly reduce the power
consumption of the start-up res istor; and when the output power
becomes smaller, 5920 will auto matically lower its operating frequency to
enable very lo w standby power consumption.
W hen the po wer tube stops, the internal circuit will turn the power
tube reverse bias to greatly raise the voltage resistant capacity of OC pin.
This will ensure the safety o f the po wer tube. The internal design of the
5920 is also provided with o ver-load and saturation preventive function
capable of preventing diso rders such as overload, transformer saturation
and output short-circuit, so as to increase the reliab ility of the power
supply. A voltage reference of 2.5V is also integrated in the 5920 to
provide accurate power supply to the clock circuit, and the clock
frequency may be set by external timing capacitance. P resently, standard
DIP8 package and environmental friendly lead-free package in
compliance with Euro pean standard can be supplied.
FE AT URE S
¦ Built-in 750V high voltage power switching tube with minimal
external parts count
¦ Latched P WM and pulse-by-pulse current limiting inspection
¦ Reduced frequency at low output with standby po wer consumption
below 0.25W
¦ Built-in slope and feedback compensation function
¦ Separate upper limit current inspection controller to handle timely
the o ver-current and overload of the controller
¦ Turn off periodic bias output of the emitter to improve the voltage
resistance of the power tube
¦ Built-in thermal protective circuit
¦ Complete start-up using amplification of the switching power tube to
reduce the power consumption of the start-up resistor more than ten
times
¦ Automatic VCC over-voltage limit
¦ Broad voltage output power up to 12W and narrow voltage output
power up to 18W
Applications
¦ P ower Adaptors(traveling chargers ,stand-alone power set)
¦ Internal power supply for Energy-Saving Appliances (such as
electro magnetic oven, microwave oven and etc.)