Voltage level shifting circuits for signal levels and/or power supply voltage levels using constant voltage circuit elements, lighting apparatuses and methods of operating the same

A level shifting circuit comprising:

• a level shifting circuit input node coupled to an input signal, the input signal configured to switch between discrete voltage levels in an input voltage domain;
• a first level shifting circuit output node configured to provide first shifted voltage levels that are shifted relative to the input signal responsive to switching of the input signal;
• a first constant voltage element having a first terminal coupled to the level shifting circuit input node and having a second terminal coupled to the first level shifting circuit output node, the first constant voltage element being configured to provide a first constant voltage level shift to the input signal to provide the first shifted voltage levels responsive to switching of the input signal between the discrete voltage levels in the input voltage domain, wherein the first constant voltage element comprises a capacitor;
• a resistive element coupled to the first level shifting circuit output node, wherein a resistive value of the resistive element and a value of the capacitor provide an RC time constant that is greater than a switching frequency of the input signal;
• and
• a second constant voltage element having a first terminal coupled to the level shifting circuit input node and having a second terminal coupled to a second level shifting circuit output node, the second constant voltage element being configured to provide a second constant voltage level shift, which is opposite to a polarity of the first constant voltage level shift of the first constant voltage element, to the input signal to provide second shifted voltage levels responsive to switching of the input signal between the discrete voltage levels in the input voltage domain
• wherein the value of the capacitor is at least 5 times greater than a parasitic capacitance of a load coupled to the first level shifting circuit output node, and
• wherein the level shifting circuit is coupled to a solid state based light fixture.

A lighting apparatus comprising:

• a controller circuit configured to provide a first voltage domain switched mode power supply control signal;
• a level shifting circuit coupled to the first voltage domain switched mode power supply control signal and configured to provide a constant voltage level shift to the first voltage domain switched mode power supply control signal to provide a second voltage domain switched mode power supply control signal, wherein the level shifting circuit includes a capacitor;
• a switched mode power supply circuit configured to couple to an AC voltage source, the switched mode power supply circuit configured to provide a DC output voltage responsive to the second voltage domain switched mode power supply control signal using the AC voltage source;
• and
• at least one light emitting device (LED) coupled to the DC output voltage, the LED comprising a solid state light emitting down light, the lighting apparatus further comprising:
• a resistor coupled to the level shifting circuit, wherein a resistive value of the resistor and a value of the capacitor provide an RC time constant that is greater than a switching frequency of the first voltage domain switched mode power supply control signal;
• and
• wherein the value of the capacitor is at least 5 times greater than a parasitic capacitance of a load coupled to an output of the level shifting circuit.