Abstract: A power supply circuit for supplying power to a central processing unit (CPU) of a computer includes a pulse width modulation (PWM) controller, a control circuit, a switch circuit, a first current protection circuit, a second current protection circuit, a first power circuit, and a second power circuit. When the computer is turned on, a first current protection threshold is set by the PWM controller through the first current protection circuit. When the computer is in a standby mode, a second current protection threshold is set by the PWM controller through the second current protection circuit.

Abstract: A power supply circuit applied to a central processing unit (CPU) of a computer includes a pulse width modulation (PWM) controller, a control circuit, a first switch circuit, a second switch circuit, a first compensation circuit, a second compensation circuit, a first power circuit, and a second power circuit. When the computer is turned on, the PWM controller regulates duty cycles of pulse signals and outputs the regulated pulse signals to the first and second power circuits according to a first compensation signal, to provide a stable voltage to the CPU. When the computer is in a standby mode, the PWM controller regulates duty cycles of pulse signals and outputs the regulated pulse signals to the first power circuit according to a second compensation signal, to provide a stable voltage to the CPU.

Abstract: A sequence circuit includes first through third signal terminals, first through ninth resistors, and first through fifth electronic switches. The sequence circuit receives a first signal through the first signal terminal. The sequence circuit receives a second signal through the second signal terminal. The sequence circuit outputs a third signal through the third signal terminal. The sequence circuit is used to ensure the sequence of the first through third signals.

Abstract: A circuit protecting the components of a power circuit against passing an over-current is connected to an enable terminal of a pulse width modulation (PWM) controller of a power supply circuit on a motherboard, protecting the field effect transistors (FETs) of a first power circuit of the power supply circuit. The protecting circuit includes a first protection circuit. When a current of the first power circuit is increased, the temperatures of the FETs of the first power circuit also increase. The first protection circuit then outputs a low-level signal to the enable terminal of the PWM controller and the PWM controller stops operation thereby protecting the FETs of the first power circuit.

Abstract: A power supply circuit for a central processing unit (CPU) includes a comparing circuit, first to third switch circuits, first and second compensation circuits, a pulse width modulation (PWM) controller, a first power circuit connected to a first output pin of the PWM controller, and a second power circuit connected to a second output pin of the PWM controller. When a motherboard operates normally, the comparing circuit outputs a first control signal to control the first and third switch circuits to be turned on. The second switch circuit is turned off. The first compensation circuit provides a compensation signal to the PWM controller. When the motherboard is powered off, the comparing circuit outputs a second control signal to control the first and third switch circuits to be turned off. The second switch circuit is turned on. The second compensation circuit provides a compensation signal to the PWM controller.

Abstract: A protection circuit used to protect a first metal-oxide-semiconductor field effect transistor (MOSFET) includes a control circuit and a conversion circuit. The control circuit includes a negative temperature coefficient thermistor. When a temperature of the first MOSFET is not higher than a preset value, the control circuit controls the conversion circuit to operate normally. When the temperature of the first MOSFET is higher than the preset value, the control circuit stops the operating of the first MOSFET.

Abstract: A time sequencing circuit for a power supply unit to ensure the correct sequencing of system voltages for a computer from a power supply unit includes first to ninth resistors, first to fifth electronic switches, and a capacitor. Each of the first to fifth electronic switches includes first to third terminals. When the power supply unit outputs all required voltages, the power supply unit outputs a high-voltage level indicating power good and the computer can start up. If any one of the required voltages is not being outputted, the power supply unit outputs a low-voltage level good signal until any non-output of voltage is cured.

Abstract: A test circuit includes a first test circuit. The first test circuit includes a first light-emitting diode (LED) and a first resistor. An anode of the first LED is connected to a power supply. A cathode of the first LED is connected to a collector of a bipolar junction transistor (BJT) through the first resistor. An emitter of the BJT is grounded. A base of the BJT is connected to the power supply. A type of the BJT can be determined according to status of the first LED.

Abstract: A management device includes a control module, a display module, and an input module. The control module includes a control chip and a detecting unit. The detecting unit is used to receive first signals corresponding to a working status of hard disks and a backplane. The display module is coupled to the control chip to display parameters presenting the working status of the hard disks. The input module is used to input signals to control the display module to display more detailed parameters of the hard disks.

Abstract: An expansion board that can be inserted into a first memory slot is provided. The expansion board includes a circuit board, a number of second memory slots, a frequency divider, and an edge connector. The second memory slots and the frequency divider are arranged on the circuit board. The edge connector is set on a side of the circuit board to engage in the first memory slot. The second memory slots and the frequency divider are coupled to the edge connector, to communicate with the first memory slot via the edge connector.

Abstract: Power supply circuit comprises an under voltage protection unit and a voltage conversion unit electrically connected to the under voltage protection unit. The under voltage protection unit comprises a control chip, an npn-type bipolar junction transistor (BJT), a pnp-type BJT, and first fourth resistors. The under voltage protection unit and the voltage conversion unit are electrically connected to a power supply. When a voltage of the power supply is in a normal range, the under voltage protection unit outputs a first control signal to the voltage conversion unit. The voltage conversion unit converts the voltage of the power supply into an operation voltage, and outputs the operation voltage. When the voltage of the power supply is less than a threshold voltage, the under voltage protection unit outputs a second control signal to the voltage conversion unit, and the voltage conversion unit does not operate.

Abstract: A charge circuit for charging a battery includes a converter and a timer. The converter converts alternating current (AC) of an AC power supply into direct current (DC) and outputs a DC voltage to the battery through a first resistor. The timer is used to set a period of time and stop charging the battery after the set period of time.

Abstract: A power supply circuit comprises an under voltage protection unit and a voltage conversion unit electrically connected to the under voltage protection unit. The under voltage protection unit and the voltage conversion unit are electrically connected to a power supply. When a voltage of the power supply is in a normal range, the under voltage protection unit outputs a first control signal to the voltage conversion unit. The voltage conversion unit converts the voltage of the power supply into an operation voltage, and outputs the operation voltage. When the voltage of the power supply is less than a threshold voltage, the under voltage protection unit outputs a second control signal to the voltage conversion unit, and the voltage conversion unit does not operate.

Abstract: A detection device includes a detection circuit and a temperature measuring device. The detection circuit is used to detect an electronic component causing a short circuit in a circuit module and includes a power source, a light emitting diode (LED), a first connecting terminal connected to a cathode of the LED, and a second connecting terminal An anode of the LED is connected to an anode terminal of the power source. The first connecting terminal and the second connecting terminal are connected the first node and the second node, respectively. The temperature measuring device includes a number of test terminals for contacting the electronic components to measure and show temperatures of the electronic components. If a short circuit occurs, the LED is turned on. The short circuited electronic component is identified by reading the temperatures of the test terminals.

Abstract: A voltage protection circuit includes a first power source, a power circuit, a comparator, and a electronic switch. The power circuit provides an output voltage to the comparator. The comparator compares the output voltage with a reference voltage. The electronic switch controls the power circuit according to the comparison. When the output voltage is larger than the reference voltage, the electronic switch controls the power circuit to stop providing the output voltage.

Abstract: Voltage protection circuit connected between a current protection circuit and a load. The voltage protection circuit includes a comparator, an inverter, and an electronic switch. The current protection circuit is connected between the load and a power supply circuit for protecting the load from over-current. When an output voltage of the power supply circuit is less than a rated voltage of the load, the load receives the output voltage of the power supply circuit as normal. The power supply circuit stops outputting the output voltage to the load for protection, when the output voltage of the power supply circuit is greater than the rated voltage of the load.

Abstract: Energy saving circuit of a computer is connected between a power supply and a motherboard. The energy saving circuit includes six electronic switches and a switch. When the computer is in the stand-by state, and the switch is pressed, the motherboard of the computer receives a standby voltage and the motherboard maintains the stand-by state. The energy-saving circuit can shut off the standby voltage by pressing the switch when the computer is powered off to save energy.

Abstract: An overvoltage protection circuit includes a first connector connected to an alternating current (AC) power source, a second connector connected to an electronic device, an alternating current to direct current (AC/DC) rectifying circuit, a voltage regulating diode, a relay, a first electronic switch, and a second electronic switch. The first connector is connected to the AC/DC rectifying circuit. The AC/DC rectifying circuit is connected to the first electronic switch through the voltage regulating diode. The first electronic switch is connected to the second electronic switch. The second electronic switch is connected to the relay. The first connector is connected to the second connector through the relay.

Abstract: Power supply circuit comprises an under voltage protection module and a voltage conversion module electrically connected to the under voltage protection module. The under voltage protection module is electrically connected to a first power supply and a second power supply. The voltage conversion module is connected to the first power supply. When a voltage of the first power supply is in a normal range, the under voltage protection module offers the second power supply to power the voltage conversion module. The voltage conversion module converts the voltage of the first power supply into an operational voltage, and outputs the operational voltage. When the voltage of the first power supply is less than a threshold voltage, the under voltage protection module does not offer the second power supply to the voltage conversion module, and the voltage conversion module does not operate.

Abstract: A sequence circuit includes a power output terminal, first to third power input terminals, first to sixth resistors, first to tenth filed effect transistors (FETs), first to third inductors, a first capacitor, a second capacitor, and first to third drivers. The sequence circuit ensures that different voltages work in a correct sequence.