摘要:
An exemplary power supply circuit (200) includes a transformer (240), a first transistor (260), a start-up resistor (261), and a pulse generating circuit (250). The transformer includes a primary winding (241), a secondary winding (243), and an auxiliary winding (242). The first bipolar junction transistor includes a collector connected to a first terminal of the primary winding and an emitter grounded. The start-up resistor is connected between a second terminal of the primary winding and a base of the bipolar junction transistor. The pulse generating circuit is configured for generating a control signal according to an induction voltage of the auxiliary winding. The control signal is provided to the base of the first bipolar junction transistor for switching the first bipolar junction transistor.
摘要:
An exemplary DC to DC converter (2) includes a transistor (29), a first rectifying and filtering circuit (21), a pulse generating circuit (27) and a transformer (25). The first rectifying and filtering circuit transforms an external AC voltage to a first DC voltage. The transformer includes a primary winding (251), an assistant winding (252) connected with the primary winding in a flyback mode, and a secondary winding (253). The first DC voltage is connected to ground via the primary winding, the transistor in series. The pulse generating circuit includes a controlling terminal, a diode, a resistor, and a capacitor. One terminal of the assistant winding is connected to ground, and the other terminal of the assistant winding is connected to an anode of the diode. A cathode of the diode is connected to ground via the resistor and the capacitor in series. The controlling terminal is connected to gate electrode of the transistor.
摘要:
An exemplary power supply control circuit (200) includes a first port (201), a second port (202), a third port (203), a controllable switch (280), and a control circuit (270). The first and second ports are configured to receive a power supply voltage signal. The second and third ports are configured to output the power supply voltage signal to a load circuit. The controllable switch includes a control member (281) and a switch member (282). The control circuit is configured to control a working state of the control member. When the load circuit stops working, the control circuit controls the control member to control the switch member to be disconnected, so as to cut off the power supply voltage signal from outputting to the load circuit. A liquid crystal display (400) using the power supply control circuit is also provided.
摘要:
An exemplary DC to DC converter (2) includes a transistor (29), a first rectifying and filtering circuit (21), a pulse generating circuit (27) and a transformer (25). The first rectifying and filtering circuit transforms an external AC voltage to a first DC voltage. The transformer includes a primary winding (251), an assistant winding (252) connected with the primary winding in a flyback mode, and a secondary winding (253). The first DC voltage is connected to ground via the primary winding, the transistor in series. The pulse generating circuit includes a controlling terminal, a diode, a resistor, and a capacitor. One terminal of the assistant winding is connected to ground, and the other terminal of the assistant winding is connected to an anode of the diode. A cathode of the diode is connected to ground via the resistor and the capacitor in series. The controlling terminal is connected to gate electrode of the transistor.
摘要:
An exemplary power supply control circuit (200) includes a first port (201), a second port (202), a third port (203), a controllable switch (280), and a control circuit (270). The first and second ports are configured to receive a power supply voltage signal. The second and third ports are configured to output the power supply voltage signal to a load circuit. The controllable switch includes a control member (281) and a switch member (282 ). The control circuit is configured to control a working state of the control member. When the load circuit stops working, the control circuit controls the control member to control the switch member to be disconnected, so as to cut off the power supply voltage signal from outputting to the load circuit. A liquid crystal display (400) using the power supply control circuit is also provided.
摘要:
An exemplary backlight control circuit (200) includes a DC power supply (VDD), a load circuit (210), an input circuit (230), and a PWM IC (250). The load circuit includes two light sources (2113, 2114) and a rectifier and filter circuit (213). The input circuit includes a diode (231) and a capacitor (237). The PWM IC includes a current sampling pin (251) and an overvoltage protection pin (253). A low voltage terminal of a first one of the two light sources is connected to the current sampling pin via the rectifier and filter circuit, and a low voltage terminal of a second one of the two light sources is connected to a cathode of the diode. An anode of the diode is connected to the DC power supply and grounded via the capacitor. The overvoltage protection pin is connected to the DC power supply.
摘要:
An exemplary backlight driving circuit (20) a first power supply (260); a second power supply (270); a signal output terminal (280); an AND gate (210); a follower (220); a capacitor (290); a reverser (230); a first transistor (240), which is a N-Channel mode metal-oxide-semiconductor field-effect transistor (N-MOSFET), having a gate electrode connected to an output end of the AND gate through the follower, a source electrode connected to the signal output terminal, a drain electrode connected to the first power supply; and a second transistor (250), which is a N-Channel mode metal-oxide-semiconductor field-effect transistor (N-MOSFET), having a gate electrode connected to the output end of the AND gate through the reverser, a source electrode connected to the ground, a drain electrode connected to the signal output terminal.
摘要:
An exemplary backlight driving circuit (20) a first power supply (260); a second power supply (270); a signal output terminal (280); an AND gate (210); a follower (220); a capacitor (290); a reverser (230); a first transistor (240), which is a N-Channel mode metal-oxide-semiconductor field-effect transistor (N-MOSFET), having a gate electrode connected to an output end of the AND gate through the follower, a source electrode connected to the signal output terminal, a drain electrode connected to the first power supply; and a second transistor (250), which is a N-Channel mode metal-oxide-semiconductor field-effect transistor (N-MOSFET), having a gate electrode connected to the output end of the AND gate through the reverser, a source electrode connected to the ground, a drain electrode connected to the signal output terminal.
摘要:
An exemplary power supply circuit (20) includes a scaler (21), a field-effect transistor (23), a pulse width modulation circuit (25), and a capacitor (29). The scaler includes an output port (213). The pulse width modulation circuit includes an input port (251). The input port of the pulse width modulation circuit is grounded via the capacitor. The field-effect transistor includes a gate electrode (231), a source electrode (232), and a drain electrode (233). The gate electrode is connected to the output port of the scaler. The source electrode is grounded. The drain electrode is connected to the input port of the pulse width modulation circuit.
摘要:
An exemplary backlight modulation circuit (200) includes a pulse generator circuit (210) configured for generating a first square pulse; a voltage division circuit (230) configured for receiving the first square pulse and generating a second square pulse according to the first square pulse; an oscillator circuit (240) configured for generating a reference voltage; and an amplifier (200) comprising a negative input configured for receiving the second square pulse from the voltage division circuit, and a positive input configured for receiving the reference voltage from the oscillator circuit as a reference pulse signal, the amplifier being configured for generating a backlight adjusting signal according to the reference pulse signal and the second square pulse.