Circuitry and methodology for driving multiple light emitting devices

Circuitry comprising:

• input nodes for receiving signals from bias circuits connected in series with multiple light emitting devices, respectively, the light emitting devices connected in parallel to a power supply node;
• a detection circuit, responsive to the signals on the input nodes, for detecting which one of the light emitting devices being biased has the highest forward voltage drop;
• and
• control circuitry configured, responsive to the detection of the detection circuit, for selectively increasing and decreasing an output voltage to be applied to the power supply node so as to maintain the output voltage to be a lowest output voltage effective to drive that one of the light emitting devices.

A method for controlling circuitry having an input voltage range to drive multiple light emitting devices connected in parallel to an output node and each connected in series to respective bias circuits for biasing the light emitting devices, the method comprising the steps of:

• regulating an output voltage to be applied to the output node;
• receiving signals from the respective bias circuits,
• detecting which one of the light emitting devices being biased has the highest forward voltage drop based on the signals;
• and
• generating a control signal to control the regulating step such that the output voltage is caused to attain the lowest voltage to drive that one of the light emitting devices having the highest forward voltage drop throughout substantially the input voltage range.

Circuitry having an input voltage range for driving multiple parallel-coupled light emitting devices connected to an output node, comprising:

• a voltage regulator for controlling an output node;
• bias circuitry for setting a level of current through each light emitting device;
• the light emitting devices to be connected in circuit with the output node and bias circuitry;
• and
• regulator control circuitry for controlling the voltage regulator to maintain an operating voltage across the bias circuitry to produce substantially a lowest output voltage effective to drive one of the light emitting devices having the highest forward voltage drop throughout substantially the input voltage range.

Circuitry for driving multiple parallel-coupled light emitting devices connected to an output node, comprising:

• bias circuitry for setting a level of current through each light emitting device;
• the light emitting devices to be connected in circuit with the output node and bias circuitry;
• and
• control circuitry configured for controlling an operating voltage across the bias circuitry to be substantially a lowest output voltage effective to drive one of the light emitting devices having the highest forward voltage drop;
• and
• a voltage regulator configured, responsive to the control circuitry, for selectively increasing and decreasing an output voltage to be applied to the output node so as to maintain the operating voltage to be substantially the lowest output voltage.

A method for driving multiple light emitting devices connected in parallel to an output node and each connected in series to respective bias circuits for biasing the light emitting devices, the method comprising the steps of:

• receiving signals from the respective bias circuits,
• detecting which one of the light emitting devices being biased has the highest forward voltage drop based on the signals;
• generating a control signal to cause an output voltage to be applied to the output node to attain the lowest voltage so as to drive that one of the light emitting devices having the highest forward voltage drop;
• and
• responsive to the control signal, selectively increasing and decreasing the output voltage to regulate the output voltage.