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PDF LR5920 Data sheet ( Hoja de datos )
| Número de pieza | LR5920 | |
| Descripción | High Performance Current Mode PWM Switching Power Supply Controller | |
| Fabricantes | Leshan Radio Company | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LR5920 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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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.)
Free Datasheet http://www.datasheet4u.com/
1 page  
consumption of 5920), if IS detects the specified current o f FB, it goes
into clo se period; in the close period, OB pulls down, the po wer tube may
not be turned off immediately, but OE clamps on 2.0V (after the power
tube turns off, the base will be reverse bias and the voltage withstanding
capacity is increased); in the open or close perio d, if it detects the current
exceeding upper limit of the power tube, then the upper limit flip-flop will
be put at the preferential pos ition, forcing FB to decrease and the duty
ratio will turn smaller, so that the power tube and transformer will be
protected; at the beginning of next close period edge or if FB is belo w
1.8V, the upper limit flip-flop will reset. Bes ides, the built-in heat
Normal Stage Switching Cycle Oscillogram
LR5920
protection of 59 20 will widen the oscillato r period when the internal
temperature is above 125 to ensure the temperature of 5920 will not
exceed 135 ; the built-in slope compensation will stab ilize the
o pen/close period when 5920 is at high duty ratio or in continuo us current
mode.
W hen VCC lo wers to abo ut 4.6V, the oscillator will be closed, OSC1
and O SC2 will be at low level, and the power source will be maintained at
close period; when VCC goes on lowering to about 4.2V, 5920 will enter
the enabling stage again.
Global Oscillogram
Free Datasheet http://www.datasheet4u.com/
5 Page 
VOB and VIS
V in = 8 5 V,Vo u t = 12 V,Io ut = 1 A
LR5920
V in = 1 1 0 V,Vo u t =1 2 V,Io u t =1 A
CH2:VOB; CH4:VIS
V in = 2 2 0 V,Vo u t =1 2 V,Io u t =1 A
CH2:VOB; CH4:VIS
V in = 2 6 5 V,Vo u t =1 2 V,Io u t =1 A
CH2:VOB; CH4:VIS
Te m pe ratu re :
CH2:VOB; CH4:VIS
95
90
85
80
75
70
65
60
55
50
45
40
35
30
0.00 0.20 0.40 0.60 0.80 1.00 1.20
85V
110V
220V
265V
Free Datasheet http://www.datasheet4u.com/
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LR5920.PDF ] | |
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