Dimmer
AssigneeYazaki Corporation
InventorKimihiro Matsuura
Life of this patent
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Abstract
A dimmer comprises a PWM circuit for driving through pulse width modulation and a switching device formed on the same chip. The switching device has a driving circuit, an overheat cut-off protecting circuit, a main control FETQA to be a semiconductor switch, a first reference FETQB for generating a reference voltage and a resistor. Furthermore, overcurrent detecting means is implemented by a comparator for detecting a difference between the reference voltage and a drain—source voltage of the main control FETQA and an output thereof cuts off and controls the driving circuit so that the main control FETQA is ON/OFF controlled. The overcurrent detecting means and ON/OFF control means have a soft start function of suppressing a rush current flowing to loads of an illuminating system.
Claims6
A dimmer comprising:
- a semiconductor switch which controls power supply from a power source to a load of an illuminating system;
- a driver which outputs a driving control signal to the semiconductor switch;
- a reference voltage generator which generates a reference voltage having a voltage characteristic substantially equivalent to a voltage characteristic between terminals of the semiconductor switch;
- a overcurrent detector which detects an overcurrent of the semiconductor switch based on a difference between the voltage between the terminals of the semiconductor switch and the reference voltage;
- a switch controller which controls an ON/OFF state of the driver in response to the overcurrent detected by the overcurrent detector to control the semiconductor switch;
- and
- a modulation signal generator which generates a pulse width modulation signal to control the driving control signal,
- wherein at least the semiconductor switch, the reference voltage generator and the overcurrent detector are formed on a same chip.
Dependencies are inferred from the claim text.