Samsung Electronics
5-31
5-3-2-2. OUTPUT CONDITIONS
5-3-3. POWER CIRCUIT
5-3-3-1 INPUT
This product is equipped with a three-wire grounding-type power inlet. Insulation is class 1. When a power
device part breaks down or some trouble in this circuit causes a short, excess current runs through a fuse and
blows it to protect power devices and the system from excess current and prevent a fire.
Input filter of power input terminal removes line noise flown in from outside and reduces noise which is
made in power circuit and logic part and conducted or radiated through power cords.
AC input voltage is rectified by bridge diode of full wave rectifier, is converted to DC voltage by smoothing
circuit, and switches the power device of this voltage.
As switching is in RCC(Ringing Choke Converter) mode, switching frequency changes from about 50KHz to
100KHz.
PWM(Pulse Width Modulation) Control Circuit adjusts the duty of the switching device by sensing the
change of output voltage, and protects this product from excess current by receiving signals from excess cur-
rent detecting circuit.
5-3-3-2 DRIVING CIRCUIT (START-UP CIRCUIT)
If you insert a power plug into AC outlet, full-wave rectified DC output voltage is generated at input elec-
trolysis condenser and supplied to the gate of a switching device through driving resistance. This voltage dri-
ves the switching device. Once it is driven, it continues to switch via PWM control circuit with power sup-
plied by auxiliary coil Nb.
5-3-3-3 SWITCHING CIRCUIT (VOLTAGE STABILIZATION)
11.75V of 2nd voltage is detected by voltage detector and feeds back through photo coupler to 1st PWM
Control Circuit signals compared by error amplifier.
PWM Control Circuit controls the gate of power transistor according to the feedback voltage so as to supply
load with stable output voltage.
NO
ITEM
CH1
CH2
CH3
1
RATED OUTPUT VOLTAGE
+5.0V
+11.75V
+30V
2
RATED OUTPUT CURRENT
0.5A
0.8A
0.5A
3
MAXIMUM LOAD CURRENT
0.8A
1.3A
0.76A
4
LOAD CHANGE RANGE
0.1 ~ 0.8A
0.03 ~ 1.3A
0.05 ~ 0.76A
Содержание SF-4300C
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