Allegro Microsystems, LLC

Shashank Wekhande

Vijay Mangtani

Gregory Szczeszynski

Mir Mahin

John Humenick

Sihua Wen

An electronic circuit includes circuit portions for identifying a largest voltage drop through one of a plurality of series connected diode strings and for controlling a boost switching regulator according to the largest voltage drop. The electronic circuit can sense an open circuit series connected diode string, which would otherwise have the largest voltage drop, and can disconnect that open circuit series connected diode string from control of the boost switching regulator. Another electronic circuit includes a current limiting circuit coupled to or within a boost switching regulator and configured to operate with a diode load. Another electronic circuit includes a pulse width modulation circuit configured to dim a series connected string of light emitting diodes.

Electronic circuit for driving a diode load

A DC-DC converter includes independent first and second outputs to drive respective first and second loads from a common boost module. In one embodiment, a first linear regulator controls a first controlling device for the first output and a second linear regulator controls a second controlling device for the second output. The load requiring the higher voltage controls the boost module.

Methods and apparatus for DC-DC converter having independent outputs

A capacitor charging circuit is provided with a primary side output voltage sensing circuit for generating a control signal indicative of whether the output voltage has reached a desired level. The control signal is unaffected by voltage spikes occurring when the main switch is turned off. In one embodiment, the circuit filters the primary side voltage for comparison to a reference voltage in order to provide the control signal. In another embodiment, an AND gate provides the control signal indicating that the output voltage has reached the desired level only in response to the primary side voltage being greater than a reference voltage and the secondary current being discontinuous. In a further embodiment, an AND gate provides the control signal indicating that the output voltage has reached the desired levels only in response to a predetermined delay occurring after the primary side voltage becomes greater than a reference voltage and the secondary current being discontinuous. According to a further aspect of the invention, an auxiliary switch is provided to reduce the reverse recovery time of the output diode in order to speed up the capacitor charging time.

Capacitor charging methods and apparatus

Apparatus for detecting failure of an isolation device includes a current sensor to sense current through the isolation device and a circuit responsive to the current sensor output signal and to an enable signal that controls the isolation device for providing an Early Failure Warning (EFW) signal indicative of whether the isolation device has failed. The enable signal is at a first logic level when the isolation device is on and is brought to a second logic level to disable and test the isolation device. Also described is a method of detecting a failure of an isolation device including disabling the isolation device, sensing a current through the isolation device, and providing an EFW signal indicating that the isolation device has failed if the current through the isolation device is greater than a predetermined level when the isolation device is disabled.

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Nashua, NH, United States of America

Shashank Wekhande