Nxp B.v.

Henricus T P J Van Elk

Wilhelmus Hinderikus Maria Langeslag

Peter Hubertus Franciscus Deurenberg

Jeroen Kleinpenning

Frank Van Rens

The present invention relates to a detection circuit () capable to detect a rectified phase-cut or sinusoidal wave-form using its duty cycle or average value and in response, to select the respective dim mode amongst the linear phase-cut and step-dimming. The circuit () receives the rectified waveform with its duty cycle, which is derived through a comparator () and converted into a DC signal. The latter which is controlled by the duty cycle is then compared to a reference level () through another comparator () that, in response, supplies a signal controlling a switching device (). The switching device () will be thus automatically connected either to one set signal level when the DC signal is greater than the reference level (), namely when the circuit () detects a rectified sinusoidal waveform, or to the same level as the DC signal when the DC signal is less than the reference level (), namely when the circuit () detects a rectified phase-cut waveform.

Waveform detection and combined step and linear dim control

The present invention relates to a dimmer control circuit () capable to detect whether a phase-cut dimmer is connected using an average signal (VDCI) derived from the mains voltage. The average signal (VDCI) or a signal (VDCI_ls) derived from (VDCI), ranging from a minimum value to a maximum value, is compared to a dimming threshold (Vdim_th) through a phase-cut detecting unit (). The comparison result is used to control the state diagram of a dimmer control logic () by selecting the step dimming mode (STD) or the phase-cut dimming mode (PCD). The output (OUT) of a switching unit () is determined by the state diagram of the dimmer control logic () in such a manner that the phase-cut dimming mode (PCD) is prioritized above the step-dimming mode (STD) and the maximum level of the STD states is depending on the mains voltage and application adjustable.

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Ravensteinn, Netherlands

Henricus T P J Van Elk