Dynamic step dimming interface

A system, comprising:

• a ballast configured to be connected to a source of an oscillating current and to energize a lamp, wherein the ballast comprises a lamp control circuit responsive to a mode command indicating whether the lamp will be energized in one of a dim mode and a normal mode;
• a voltage monitor comprising an input configured to receive the oscillating current and an output configured to indicate a voltage level of the oscillating current signal;
• a central processing circuit comprising a first input connected to the output of the voltage monitor, a second input, a third input, a first output connected to the lamp control circuit to provide a mode command indicating that the lamp will be energized in one of a dim mode and a normal mode, and a second output to provide a reference voltage indicative of the voltage level of the oscillating current;
• a rectifier circuit comprising an input configured to receive the oscillating current, an output configured to provide a rectified voltage indicative of the oscillating current, a resistive voltage divider circuit to limit a peak voltage of the oscillating current, and a capacitive circuit to remove high-frequency noise;
• an auto-programmable comparator circuit comprising a first input connected to the rectifier circuit, a second input connected to the second output of the central processing circuit, and an output configured to provide one or more pulses indicative of a power level applied to the lamp;
• a pulse counter comprising an input to receive the one or more pulses from the auto-programmable comparator circuit and an output connected to the second input of the central processing circuit to provide a second voltage indicative of the state of the lamp controlled by the lamp control circuit;
• and
• a clock circuit comprising an output connected to the third input of the central processing circuit to provide a time reference for the one or more pulses;
• wherein the central processing circuit is responsive to the one or more pulses and to the voltage level output by the voltage monitor to provide the mode command.

A method of energizing a lamp in one of a dim mode and a normal mode, comprising:

• monitoring a voltage level of an oscillating current;
• determining a reference voltage corresponding to the voltage level of the oscillating current;
• calculating whether a voltage level of a rectified voltage corresponding to the oscillating current is greater than a determined reference voltage, and in response:
• when the voltage level of the rectified voltage is greater than the determined reference voltage:
• verifying that the voltage level of the rectified voltage continues to be greater than the determined reference voltage for a period of time;
• and
• in response, generating a dim operating mode command for a lamp control circuit to place the lamp in a dim operating mode;
• otherwise if the voltage level of the rectified voltage is not greater than the determined reference voltage for any portion of the period of time, continuing to monitor the voltage level of the oscillating current;
• when the voltage level of the rectified voltage is not greater than the determined reference voltage:
• verifying that the voltage level of the rectified voltage continues to be not greater than the determined reference voltage for the period of time;
• in response, determining whether an indication exists for operating the lamp in the dim operating mode;
• wherein if the indication to operate in the dim operating mode exists, generating a dim operating mode command for a lamp control circuit to place the lamp in a dim operating mode;
• wherein if the indication to operate in the dim operating mode does not exist, generating a normal operating mode command for the lamp control circuit to place the lamp in a normal operating mode;
• otherwise, if the voltage level of the rectified voltage is greater than the determined reference voltage for any portion of the period of time, continuing to monitor the voltage level of the oscillating current.