摘要:
In one embodiment, a sensing circuit includes a sense transistor and a compensation circuit to improve the accuracy of a sensing signal formed by the sensing circuit.
摘要:
In one embodiment, a sensing circuit includes a sense transistor and a compensation circuit to improve the accuracy of a sensing signal formed by the sensing circuit.
摘要:
An apparatus for measuring the dc current in a power supply circuit includes a transformer having a primary winding, a core and a secondary winding, a current generator, a pulse generator, and a measurement circuit. The secondary winding of the transformer is coupled to the power supply circuit, wherein the power supply circuit supplies dc current to the secondary winding generating a second field of magnetic flux. The current generator, coupled to the primary winding of the transformer, supplies an ac current to the primary winding generating a first field of magnetic flux. The pulse generator, coupled to the primary winding, generates a pulse when the first field of magnetic flux is substantially equal to the second field of magnetic flux. The measuring circuit, coupled to the current generator and responsive to the pulse generator, measures the ac current from the current generator in response to a pulse received from the pulse generator, wherein the ac current is proportional to the dc current.
摘要:
A motor speed control circuit includes a temperature sensor providing a first voltage output which is proportional to the temperature and a control voltage generator having an internal voltage reference receiving the first output as an input. The control voltage generator develops a control voltage representative of a desired motor speed profile which varies substantially linearly between a first predetermined temperature and a second predetermined temperature and supplies the control voltage to a motor drive circuit with a motor drive voltage at its output. The control voltage is fed back to the temperature sensor to achieve a controlled, fast rising slope. A second feedback circuit results in a reduced slope of the voltage between the second predetermined temperature and a third predetermined temperature at which an alarm signal is generated. The circuit also is able to detect a stopped motor and provide an alarm.
摘要:
A primary voltage generation circuitry and an auxiliary voltage generation circuitry is provided to a DC-DC converter. The primary voltage generation circuitry generates a primary voltage output, and the auxiliary voltage generation circuitry, in cooperation with the primary voltage generation circuitry, generates an auxiliary voltage output. The primary voltage generation circuitry includes a switching circuit element and an inductor element, whereas the auxiliary voltage generation circuitry includes an inductor element complementary to the inductor element of the primary voltage generation circuitry. The inductor element of the auxiliary voltage generation circuitry references the primary voltage output, and relies on a minimum load at the primary voltage output. Preferably, the auxiliary voltage generation circuitry further includes reference circuitry elements for regulating the auxiliary voltage output to a precise assurance range. As a result, multiple high precision voltage outputs are generated efficiently by the DC-DC converter in a cost effective manner.
摘要:
In one embodiment, a leadframe for a semiconductor package includes a source connection area for one transistor and a drain connection point for a second transistor, and a common connection for using a connection clip to couple a drain of the first transistor to a source of the second transistor and to the common connection.
摘要:
A circuit and method for driving a field effect transistor is disclosed. A switching circuit includes a driver device having a signal input, a supply voltage input, and an output. The driver output is coupled to a JFET. A converter couples to the JFET and provides an output of the switching circuit. When enabled, a switching device couples this switching circuit output to the gate of the JFET, thus causing the JFET to be driven into conduction.
摘要:
A power supply including a DC—DC converter with multiphase current sharing and ripple regulation. In one embodiment, the disclosed power supply includes a plurality of power drivers coupled to supply power to the supply output. The power drivers are cyclically enabled to provide multiphase current sharing. Ripple regulation is provided with a hysteretic comparator that is coupled to receive feedback from the power supply output. The hysteretic comparator is used to clock or advance a select circuit, which is used to cyclically enable each one of the plurality of power drivers. A reset circuit is included to reset the hysteretic comparator in the event that the hysteretic comparator has not switched for an excessive amount of time. A supply current sensor is used to monitor the current drawn by the plurality of power drivers. As the amount of current drawn by any of the plurality of power drivers rises, the on cycle time of the power driver that is delivering power to the power supply output at that particular time is shortened, enabling the next power driver to deliver power.
摘要:
A battery charging circuit, particularly useful in a laptop computer system, includes a voltage input terminal coupled to a dc voltage. A first switch couples the voltage input terminal to an output coupled to the battery through a current sense resistor. A first current sink which is on when the charger circuit is on draws current from the input side of the current sense resistor through a first resistor to develop a first voltage. This voltage and a voltage coupled through a second resistor from the battery side of the sense resistor are inputs to a comparator, the output of which controls the first switch. A second current sink, when on, draws current through the second resistor causing the first switch to be held off, turning the charging circuit off. An ON/OFF terminal, to which a variable duty cycle square wave is supplied, controls the turning on and off of the first and second current sinks, with the length of the duty cycle controlling the average current supplied to the battery.
摘要:
A circuit used in combination with a redundant power supply system to electrically disconnect its failed power supplies. The circuit comprises a power FET, a rectifier and filter circuit, a start-up circuit and a shut-down circuit. The rectifier and filter circuit rectifies an input AC waveform and subsequently filters a resultant DC voltage which is subsequently used to supply an output voltage at an output terminal connected to the power FET. In parallel with the rectifier and filter circuit, the start-up circuit is coupled to a gate of the power FET to ramp the voltage supplied to that gate slowly turning on the power FET. Coupled in parallel with the start-up circuit, the shut-down circuit conducts voltage from the gate thereby turning-off the power FET to preclude current from other power supplies of the redundant power supply system to pass current to its failed power supply.