Abstract: A power supply circuit for a CPU (central processing unit) includes a CPU, a power supply, a plurality of voltage adjustment modules, a pulse width modulator, a plurality of resistivity selection modules, and a module management unit. The resistivity selection module includes an electronic switch, a first resistor, a second resistor, a third resistor, and a fourth resistor. When the CPU operates abnormally, the power supply circuit utilizes the resistors in the resistivity selection module as voltage dividers, thereby restricting MOSFET or other components to operate in a normal voltage range.

Abstract: An overcurrent protection device includes a power input terminal, a power output terminal, a first signal terminal, a second signal terminal, a testing circuit, and a switch element. The power input terminal and the first signal terminal are connected to a power supply. The power output terminal and the second signal terminal are connected to a computer motherboard. If the first and second terminals are disconnected from each other when the computer motherboard works, the power supply stops working. The testing circuit includes a fixed resistor and a control chip parallel connected between the power input and output terminal. The control chip stores a predetermined voltage threshold, and detects voltage between the two terminals of the fixed resistor, and compares the measured voltage with the predetermined voltage threshold. The switch element disconnects the first and second signal terminals when the measured voltage is greater than the predetermined voltage threshold.

Abstract: A power control system includes a rectifier circuit, a buck circuit, a voltage divider circuit, a control circuit, and a switch circuit. A first terminal of the rectifier circuit is connected to an alternating current (AC) power supply. A second terminal of the rectifier circuit is connected to a first terminal of the buck circuit and a first terminal of the voltage divider circuit. A first terminal of the control circuit is connected to a second terminal of the buck circuit. A second terminal of the control circuit is connected to a second terminal of the voltage divider circuit. A third terminal of the control circuit is connected to the switch circuit. The switch circuit is connected to the AC power supply and an electronic device.

Abstract: An RC test circuit includes an RC circuit, a digital rheostat, a control chip, and an oscillograph. The RC circuit includes a plurality of positive terminals and a plurality of negative terminals. The digital rheostat includes a plurality of rheostats each including a sliding terminal and a fixed terminal. The sliding terminals are correspondingly connected to the positive terminals while the fixed terminals are correspondingly connected to the negative terminals. The control chip is connected to the digital rheostat, and configured for controlling the digital rheostat to change the resistance of each rheostat. The oscillograph is connected to the RC circuit for displaying a waveform of the RC circuit.

Abstract: A driver circuit drives a pulse width modulation (PWM) controller. The driver circuit includes an enabling circuit, a power supply input control circuit, a stabilizing circuit, and a discharge circuit. The stabilizing circuit is electrically connected to the PWM controller. The power supply input control circuit is electrically connected between the enabling circuit and the stabilizing circuit. The discharge circuit is electrically connected between the stabilizing circuit and the ground. In response to the driver circuit working in normal operation, the enabling circuit enables the power supply input control circuit to output a working voltage to the stabilizing circuit, and in response to the process of the driver circuit restarting, the enabling circuit enables the power supply input to stop outputting power supply to the stabilizing circuit. The discharge circuit leads a residual voltage of the stabilizing circuit to the ground, during the process of the driver circuit being restarted.

Abstract: A motherboard includes a motherboard power supply connector and a time delay circuit. The motherboard power supply connector connects a power supply unit. The motherboard power supply connector has a power supply on pin and a power good pin. The power good pin is configured for receiving a power good signal from the power supply unit. The time delay circuit has an input terminal and an output terminal. The input terminal is configured for receiving a power supply on signal. The output terminal is connected to the power supply on pin and is configured for sending the power supply on signal to the power supply on pin after a time delay determined by the time delay circuit.

Abstract: A resistance determining system for an over voltage protection (OVP) circuit, includes an external power source, a microcontroller, a digital rheostat and a display unit. The external power source supplies an external voltage to the OVP circuit. The microcontroller stores an over voltage value. The microcontroller is connected to the external power source and configured to detect the external voltage and compare the external voltage with the over voltage value. The digital rheostat is connected to the microcontroller and includes a first rheostat having two connection terminals respectively connected to two first connection ends of the OVP circuit. The microcontroller adjusts the first rheostat to be a first resistance value to activate the OVP circuit when the external voltage is substantially equal to the over voltage value. The display unit is connected to the microcontroller and configured to display the first resistance value.

Abstract: A measuring device for a hard disk drive includes a first input node, a hard disk drive having a first input terminal, the first input terminal being coupled to the first input node to provide power to the hard disk drive. A first input current sampling unit is coupled between the first input node and the first input terminal of the hard disk drive to obtain a first input current Iin1. A first input voltage sampling unit is coupled to the first input terminal of the hard disk drive to obtain a first input voltage Uin1. A control unit is coupled to the first input current sampling unit and the first input voltage sampling unit to receive the first input current and the first input voltage.

Abstract: A driving voltage adjusting circuit includes a digital rheostat, a control chip, a low dropout regulating circuit, and a driving circuit. The control chip is connected with the digital rheostat, and configured for adjusting the resistance of the digital rheostat. The low dropout regulating circuit is connected with the digital rheostat and outputs an output voltage according to the resistance of the digital rheostat. The driving circuit comprising a number of switch elements connected with each other and a driver configured for driving the switch elements, each of the switch elements comprising a first terminal, a second terminal, and a control terminal configured for controlling connection and disconnection of the first terminal and the second terminal; the first terminal and the second terminal connected with the control chip, the driver is connected with the low dropout regulating circuit and output an driving voltage to the control terminal.

Abstract: A buck converter includes a first MOSFET and a second MOSFET connected in series, a PWM module coupled to gates of the first MOSFET and the second MOSFET, and a control unit being coupled to the input current acquired unit, the input voltage acquired unit, the output current acquired unit, the output voltage acquired unit and the PWM module respectively, wherein the control unit controls a switch frequency of the PWM module and acquires the input current, the input voltage, the output current and the output voltage from the input current acquired unit, the input voltage acquired unit, the output current acquired unit and the output voltage acquired unit respectively.

Abstract: A computer motherboard includes a motherboard substrate defining a CPU loading area and a CPU voltage regulator power supply layout area. The power supply layout area is equally divided into a number of phase regions, and each of the phase regions has a number of spaced circuit layers. The circuit layers in the phase regions are symmetrical about a central axis of the CPU loading area, and a difference between each two simulating impedances between an impedance center of each of the phase regions and a loading center of the CPU loading area is within 1%.

Abstract: A solar power supply for an automobile air conditioner includes a switch unit, a solar energy unit, and a control unit. The switch unit outputs a switch signal. The solar energy unit includes a solar panel, a solar charging circuit, a DC (direct current) voltage transformation circuit, and a battery. The control unit receives the switch signal, enables the solar charging circuit and the DC voltage transformation circuit in response to the switch signal to charge the battery and transform the voltage received from the battery to a stable voltage, respectively, and provides the stable voltage to an automobile air conditioner.

Abstract: A measurement circuit includes a switch unit with a number of keys selectively pressed to output different resistance regulating signals. A resistance setting circuit receives the resistance regulating signals and connects different resistances to a control circuit. The control circuit obtains a voltage according to the chosen resistance by the resistance setting circuit and compares the voltage with a preset voltage. If the voltage is greater than the preset voltage, the control circuit outputs a high level signal to a control pin of a pulse width modulation (PWM) controller, to control a voltage unit to output a voltage. If the voltage is less than the preset voltage, the control circuit outputs a low level signal to the control pin of the PWM controller, to control the voltage unit to not output a voltage. A display unit displays the chosen resistance.

Abstract: A measurement circuit includes a switch unit with a number of keys selectively pressed to output different resistance regulating signals. A resistance setting circuit receives the resistance regulating signals and connects different resistances to a voltage circuit and a current circuit. The voltage circuit outputs different voltages. The current voltage receives a voltage from the voltage circuit and outputs a current to a capacitor. A detecting circuit measures a temperature of the capacitor and outputs the temperature to the resistance setting circuit. The resistance setting circuit compares the received temperature with a preset temperature. If the received temperature is equal to or greater than the preset temperature, the resistance setting circuit outputs short-circuit information of the capacitor. If the received temperature is less than the preset temperature, the resistance setting circuit outputs normal information of the capacitor. A display unit displays the information of the capacitor.

Abstract: A multimeter includes a main body, two probes extending from the main body, a battery unit arranged in the main body, and a charging system arranged in the main body and configured for charging the battery. The charging system includes a microcontroller with an external input voltage sampling circuit, a battery voltage sampling circuit and a voltage regulator circuit each electrically connected the microcontroller. The microcontroller compares sampled signals from the external input voltage sampling circuit and the battery voltage sampling circuit, and controls the voltage regulator circuit to regulate the external input voltage to be applicable to the battery based on the comparison.

Abstract: A buck converter includes an input unit, an inductor, and a filter capacitor. The input unit has an input node connected to a power source and an intermediate node connected to an output node through the inductor. The filter capacitor is coupled between the output node and ground. A first RC integral circuit is in parallel connection with the first inductor, a voltage acquired unit is in parallel connection with the capacitor of the RC integral circuit for obtaining a voltage U1 between the two terminals of the second capacitor. A control unit is coupled to the first voltage acquired unit for receiving the voltage U1 of the capacitor.

Abstract: A motherboard detection device for a motherboard having a plurality of power input terminals. The power detection device includes a current sampling module, a voltage sampling module, a processor, and a display unit. The current sampling module is connected to the power input terminals for obtaining the current of each power input terminal. The voltage sampling module is connected to the power input terminals for obtaining the voltage of each power input terminal. The processor is connected to the current sampling module and the voltage sampling module for acquiring the current and the voltage of each power input terminal and calculating the input power of each power input terminal based on the current and the voltage of each power input terminal to obtain input power data. The display unit is connected to the processor for receiving the input power data from the processor and displaying the input power data.

Abstract: An output voltage adjustment circuit for buck circuits includes a microcontroller, first to eighth keys, and a display unit. The first to eighth keys input voltage adjustment signals to the microcontroller. A first input pin of the microcontroller is connected to a voltage output terminal. A second resistor is connected between the first input pin of the microcontroller and ground. A first to a sixth input/output pin of the microcontroller are connected to the display unit. A first to an eighth output pin of the microcontroller are connected to a pulse width modulation (PWM) controller. The first to eighth keys are selectively activated to provide voltage adjustment signals to the microcontroller, sampling output voltages of the voltage output terminal, comparing with a predetermined voltage, controlling the PWM controller to fine tune the duty cycle to output a stable voltage from the voltage output terminal. The display unit displays the voltages on the voltage output terminal.

Abstract: A measurement circuit for overload protection is applied in a buck circuit. The buck circuit includes a pulse width modulation (PWM) controller and a voltage output terminal. The measurement circuit includes a resistance setting circuit to connect different resistances to the PWM controller of the buck circuit. A switch circuit turns the measurement circuit on or off. A current collection circuit receives a voltage from the voltage output terminal of the buck circuit and transforms the received voltage to a current, and amplifies the transformed current and outputs the amplified current to the resistance setting circuit. The resistance setting circuit chooses a resistance through comparison of the amplified current with a preset current. A display unit displays the chosen resistance.

Abstract: A buck converter includes a first electrical switch and a second electrical switch connected in series, a PWM module coupled to the gate of the first electrical switch through a first adjustable resistance module and coupled to the gate of the second electrical switch through a second adjustable resistance module, a filter circuit coupled between the connecting node of the two different electrical switches and an output node, and a control module for adjusting values of the first adjustable resistance module and the second adjustable resistance module and acquiring a voltage value from the connecting node.