Stmicroelectronics S.r.l.

Stmicroelectronics International N.v.

Giuseppe Catalisano

Akshat Jain

Rosario Scollo

Ranajay Mallik

Luigi Abbatelli

A drive transistor is connected to a resonant load in a low-side drive configuration. The voltage across the conduction terminals of the drive transistor is sensed and compared to an over-voltage threshold. An over-voltage signal is asserted in response to the comparison. The drive transistor is controlled by a PWM control signal in normal mode. In response to the assertion of the over-voltage signal, the drive transistor is forced to turn on (irrespective of the PWM control signal) to relieve the over-voltage condition. Operation of the circuit may be disabled or forced into soft start mode in response to the assertion of the over-voltage signal. Additionally, the pulse width of the PWM control signal may be reduced in response to the assertion of the over-voltage signal.

Over-voltage protection circuit for a drive transistor

A driving device for a lamp, in particular an HID lamp, the device including a first circuit to convert a network input voltage into a output direct voltage, a second circuit that receives the direct voltage as an input and converts the direct voltage into an alternating signal for supplying the lamp. The first circuit includes a transformer provided with a secondary winding elements a center tap. The driving device further includes at least two capacitive elements connected to the center tap of the secondary winding of the transformer and coupled with the ends of the secondary winding and with the input of the second circuit.

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Carlentini, Italy

Giuseppe Catalisano