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: An inductance measurement circuit includes a control circuit, a constant current supply circuit, a voltage detecting circuit, and a display circuit. The control circuit controls the constant current supply circuit to supply a first current for a first inductor. The control circuit controls the voltage detecting circuit to detect a voltage on the first inductor. The control circuit obtains an internal resistance of the first inductor by dividing the first voltage by the first constant current. The display circuit displays the internal resistance of the first inductor.

Abstract: A measurement system includes a control circuit, a measurement circuit, and a display circuit. The measurement circuit includes a first capacitor. The control circuit outputs control signals to control first or second inductors and the first capacitor to compose an LC circuit. Inductance can be gained according to the formula: L = 1 4 ? ? · f 2 · C , where L stands for the inductance, f stands for a frequency of the LC circuit, ? stands for ratio of a circle's circumference to its diameter, and C stands for capacitance of the first capacitor. The control circuit also controls the first and second inductors to be connected in parallel and then connected in parallel to the first capacitor to compose an LC circuit, to determine a coupling inductance. A leak inductance is equal to a half of the coupling inductance. The display circuit displays the inductances of the first and second inductors and the leak inductance.

Abstract: A measurement circuit includes an instruction input unit, a charging circuit to charge a capacitor, a charging and discharging circuit to control the capacitor to leakage discharge, a control circuit, a first amplifying circuit, and a display unit. The control circuit receives a measurement instruction through the instruction input unit to control the charging circuit to charge the capacitor, and receives a stop charging signal from the charging circuit when a voltage of the capacitor reaches a saturation voltage for controlling the charging circuit to stop charging the capacitor. The first amplifying circuit measures a leakage voltage of the capacitor, amplifies the measured leakage voltage, and outputs the amplified leakage voltage to the control circuit. The display unit displays the leakage voltage of the capacitor.

Abstract: An impedance measuring device for an electronic component includes a constant voltage source, a load supplying circuit, a voltage detection circuit, and a controller. The constant voltage source outputs an input voltage. The load supplying circuit supplies a load resistor that is electronically connected in series with the electronic component between the constant voltage source and ground. The voltage detection circuit detects a voltage across the load resistor. The controller receives the voltage across the load resistor from the voltage detection circuit, and calculates an equivalent impedance of the electronic component according to the input voltage, the voltage across the load resistor, and the resistance of the load resistor.

Abstract: An input power measuring device includes a board with an edge connector, a first dual inline memory modules (DIMM) socket, a resistor, a differential amplifier circuit, a voltage dividing circuit, a display screen, and a controller. When the edge connector is inserted into a second DIMM socket of a motherboard and the motherboard is powered on, the resistor samples first current, and converts the first current into a first voltage. The differential amplifier circuit amplifiers the first current to a second current. The voltage dividing circuit divides the first voltage, and outputs a second voltage. The controller converts the second current into a third current, converts the second voltage into a third voltage, and calculates a power according to the third current and the third voltage.

Abstract: A test device includes a transformer, a loop analyzer, and a protection circuit. The protection circuit includes a control unit, a signal acquisition and amplification unit, and an electronic switch. When the loop analyzer outputs a signal, the signal acquisition and amplification unit acquires the signal output from the loop analyzer, amplifies the acquired signal, and outputs the amplified signal to the control unit. The control unit transforms the received signal from analog form to digital form, and compares the digital signal with a reference value. If the digital signal is greater than the reference value, the control unit outputs a control signal to the electronic switch, to turn off the electronic switch. The signal output from the loop analyzer cannot be transmitted to a buck circuit.

Abstract: A power sequence circuit includes a control circuit and a plurality of output circuits. The control circuit provides a plurality of power-on signals and a plurality of power-off signals according to a power-on sequence and a power-off sequence. Each of the output circuits provides an output voltage when receiving a corresponding one of the power-on signals, and stops providing the output voltage when receiving a corresponding one of the power-off signals. The power sequence circuit controls the output voltages by the power-on sequence and the power-off sequence.

Abstract: A power supply test device includes a function generator, a loading circuit, a current detection circuit, and a controller. The function generator outputs a square-wave signal to the loading circuit. The loading circuit is electronically connected to a power supply, the loading circuit regulates an output current of the power supply according to the square-wave signal. The current detection circuit cooperates with the controller in detecting a slope of the output current. The controller compares the detected slope with a preset value, and regulates the square-wave signal according to the comparison to regulate the slope of the output current.

Abstract: A ground test circuit for a power supply unit includes a sampling circuit, a converting circuit, a processing circuit, and a switch circuit. The sampling circuit detects a voltage difference between a first ground terminal and a second ground terminal. The converting circuit converts the voltage difference to a digital value. The processing circuit compares the digital value to a predetermined value. As long as the digital value is smaller than the predetermined value, the switch circuit allows an external power source to be connected to the power supply unit. Thereby, the ground test circuit controls the connection between the external power source and the power supply unit according to the result of comparison of values done by the processing circuit.

Abstract: A measurement card includes a circuit board, an edge connector on a bottom edge of the circuit board, a port arranged on the circuit board, and a single-pole double-throw switch for connecting the port to either a first or a second pin of the edge connector to tests the VDDQ and VTT outputs of a memory slot.

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.

Abstract: A keyboard includes a fingerprint input unit, a storage unit, a switch unit, and a control unit. The fingerprint input unit receives fingerprint information of a user. The storage unit stores a fingerprint model. The control unit is connected to the fingerprint input unit, the storage unit, and the switch unit. The control unit receives the fingerprint information of the user from the fingerprint input unit and compares the received fingerprint information with the fingerprint model stored in the storage unit. If the received fingerprint information is consistent with the fingerprint model, the control unit controls the switch unit to be turned on, to output a control signal to power on a computer connected to the keyboard.

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 apparatus tests currents from a plurality of power ports of a power supply unit (PSU), to test minimum value of the currents. The apparatus includes a connector, a controller, a time sequence detection circuit, and a plurality of load circuits. The time sequence detection circuit detects a start time-sequence of the ports of the PSU. Each load circuit is electronically connected to a power port of the PSU. The controller activates and applies each load circuit to a power port of the PSU according the start time-sequence of the ports of the PSU, controls a current-draw of each load circuit until the PSU works in a normal state, and displays the established minimum output current when the PSU works in the normal state.

Abstract: A power supply circuit includes a pulse width modulation (PWM) chip, a number of phase circuits, a voltage output end, and a spike suppression circuit. The spike suppression circuit is connected to each of the phase circuits and the voltage output end. The PWM chip controls all of the phase circuits to alternately output power supply voltages according to a predetermined sequence. The spike suppression circuit receives the power supply voltages, and filters out voltage spikes in the power supply voltages, thereby outputting steady voltages to the voltage output end.

Abstract: A temperature detecting apparatus for adjusting direction of airflow from a fan according to thermal status in an electronic device, includes a detection module, a control module, and a driver module. The detection module detects temperatures of a plurality of position coordinates in the electronic device and converts the detected temperatures and the plurality of position coordinates corresponding to the detected temperatures to first voltage signals. The control module receives the first voltage signals and compares the temperatures of corresponding position coordinates to output a position coordinate of the greatest temperature according to the first voltage signals. The driver module receives the position coordinate of the greatest temperature and directs airflow towards a position having the greatest temperature.

Abstract: A minimum output current adapting circuit draws currents from a plurality of power ports of a power supply unit (PSU). The current adapting circuit includes a plurality of current adapting units and a control unit. Each current adapting unit is electronically connected to one of the power ports. Each current adapting unit is configured to increase an output current of the power port, to facilitate the output current of the power port to be greater than a request minimum output current of the power port. The control unit is electronically connected to the PSU and a processor powered by the PSU, the control unit is configured to activate each current adapting unit when the PSU starts to work, and inactivate each current adapting unit after the processor is powered on and works in a normal state.

Abstract: A driving circuit includes a switching circuit, an acquiring circuit, an amplifying circuit, and an adjusting circuit. The switching circuit includes a driving chip and a switching unit. The switching unit is connected between a power source and a load, the driving chip is configured for controlling the connection and disconnection of the switching unit. The acquiring circuit is connected between the switching unit and the load, and is configured for providing a feedback to the amplifying circuit. The amplifying circuit includes two amplifying input terminals connected to two terminals of the acquiring circuit and an amplifying output terminal outputting an amplified voltage. The adjusting circuit is connected to the amplifying output terminal and is configured for outputting different control voltages to the driving chip according to the amplified voltage. The driving chip outputs different driving voltages to the switching unit according to the control voltages.

Abstract: A device that tests an output impedance of a voltage regulator module (VRM) includes a controller, a current regulating circuit, a voltage sampling circuit, and a current sampling circuit. The voltage sampling circuit samples an instantaneous alternating output voltage of the VRM, and outputs the instantaneous alternating output voltage to the controller. The current sampling circuit cooperates with the controller in sampling the instantaneous output current of the VRM. The controller controls the current regulating circuit to regulate the instantaneous output current of the VRM until the instantaneous alternating output voltage is about equal to a predetermined reference voltage, and calculates an output impedance of the VRM according to the instantaneous alternating output voltage and instantaneous output current when the instantaneous alternating output voltage is about equal to the predetermined reference voltage.