Abstract: An electronic device comprises a power supply, a load, a switching module, a voltage converting module, and a control module. The switching module establishes an electrical connection between the power supply and the voltage converting module when the electronic device is powered on. The voltage converting module is powered on through the switching module and outputs a working voltage. The control module is thus powered on. When the electronic device is powered off, the switching module is turned off, the voltage converting module stops outputting the working voltage, and the control module is disabled.

Abstract: An exemplary tuner circuit is provided. The circuit includes a power control system, a first switch module, and a second switch module. The first switch module is connected between the power control system and an electronic component. The second switch module is connected between the power control system and a tuner. The power control system is independent of the electronic component it supplies. When the tuner is turned on, the power control system outputs a high level voltage to the first switch module and outputs a low level voltage to the second switch module, the first switch module disconnects power to the electronic component, the second switch module re-establishes a connection between the power control system and the tuner according to the low level voltage output by the power control system.

Abstract: A headphone detection circuit includes a voltage output module and a trigger signal producing module. The voltage output module is used to produce a first voltage to trigger an audio amplifier to output amplified left and right channel signals to a loudspeaker when the headphone port is not connected to the headphone, and produce a second voltage to trigger the audio amplifier to output the amplified left and right channel signals to the headphone port when the headphone port is connected to the headphone. The trigger signal producing module is used to trigger the processing unit to output left channel signals and right channel signals with a relative higher gain when receiving the first voltage, and trigger the processing unit to output the left channel signals and right channel signals with a relative lower gain when receiving the second voltage.

Abstract: An electronic device receiving a voltage from a power supply comprises a load, a control module, a switching module, and a protection module. The control module generates a first control signal. The protection module transmits the first control signal to the switching module. The switching module establishes an electrical connection between the power supply and the load in response to the first control signal. The load is powered by the power supply when the electrical connection between the power supply and the load is established. The protection module connected between the control module and the switching module prevents a reverse current or a reverse voltage supplied by the power supply from being transmitted to the control module.

Abstract: A switch circuit and an electronic device using the same include a power switch transistor, a controlling circuit, a regulated capacitor, and a capacitor. The power switch transistor is connected between an input and an output of the switch circuit. An output of the controlling circuit is connected to a controlling electrode of the power switch transistor and outputs pulse width modulation (PWM) signals to turn the power switch transistor on and off. The regulated capacitor is connected between an output of the switch circuit and ground. The capacitor is connected between an output of the controlling circuit and ground for increasing an inclination of a rising edge and a falling edge of PWM signals to slow down the speed of switching the power switch transistor on and off, thereby making the regulated capacitor charge slowly and the output voltage of the switch circuit stable.

Abstract: A switch circuit and an electronic device using the same include a power switch transistor, a controlling circuit, a regulated capacitor, and a capacitor. The power switch transistor is connected between an input and an output of the switch circuit. An output of the controlling circuit is connected to a controlling electrode of the power switch transistor and outputs pulse width modulation (PWM) signals to turn the power switch transistor on and off. The regulated capacitor is connected between an output of the switch circuit and ground. The capacitor is connected between an output of the controlling circuit and ground for increasing an inclination of a rising edge and a falling edge of PWM signals to slow down the speed of switching the power switch transistor on and off, thereby making the regulated capacitor charge slowly and the output voltage of the switch circuit stable.

Abstract: A logical level translator includes a first reference voltage provider, a second reference voltage provider, and a switching circuit. The first reference voltage provider provides a first reference voltage signal with a first logic level to a first connection terminal. The second reference voltage provider provides a second reference voltage signal with a second logic level to a second connection terminal. The switching circuit switches on a connection between the first connection terminal and the second connection terminal when a digital signal input to the first connection terminal or the second connection terminal is a logic high level signal. Then switches off the connection between the first connection terminal and the second connection terminal when the digital signals is a logic low level signal.

Abstract: A reset circuit used for resetting a processing unit of an electronic device includes a switch control unit, a first switch unit, and a reset signal generation unit. The switch control unit controls the on and off state of the first switch unit according to users' operation. The reset signal generation unit outputs a reset signal after the first switch unit has been off for a predetermined time period. The reset signal generation unit stops outputting the reset signal as the first switch unit turns on. The processing unit is reset when receiving the reset signal.

Abstract: A reset circuit used for resetting a processing unit of an electronic device includes a switch control unit, a first switch unit, and a reset signal generation unit. The switch control unit controls the on and off state of the first switch unit according to users' operation. The reset signal generation unit outputs a reset signal after the first switch unit has been off for a predetermined time period. The reset signal generation unit stops outputting the reset signal as the first switch unit turns on. The processing unit is reset when receiving the reset signal.