Low noise controller for pulse width modulated converters
AssigneePhilips Electronics North America Corporation
InventorsNaveed Majid, Stephen L. Wong
Life of this patent
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Abstract
A controller for supplying a switching drive voltage signal to a semiconductor power switch includes a wave-shaper circuit that generates a piece wise linear (PWL) waveform that slows the rate of change of the drive voltage supplied to the control electrode of the semiconductor power switch. As a result, the radiated electromagnetic interference generated by the apparatus can be appreciably reduced.
Claims13
A controller for supplying a switching signal to a semiconductor power switch, wherein said controller comprises:
- means for deriving a pulse width modulated square wave signal,
- means coupled to an output of said pulse width modulated square wave signal deriving means for generating a piece wise linear (PWL) switching signal, and
- means for coupling said PWL switching signal to a control electrode of said semiconductor power switch so as to control the switching thereof.
A switching power supply with reduced generated electromagnetic interference (EMI) comprising:
- a semiconductor power switch coupled to a source of supply voltage and to an output circuit adapted to supply a DC output voltage to a load circuit,
- means responsive to said DC output voltage for deriving a pulse width modulated square wave signal,
- means coupled to an output of said pulse width modulated square wave signal deriving means for generating a piece wise linear (PWL) switching signal having a slower dv/dt than that of a rectangular shaped drive waveform and of a value to reduce EMI generated, and
- means for coupling said PWL switching signal to a control electrode of said semiconductor power switch so as to control the switching thereof.
Dependencies are inferred from the claim text.