Secondary side post regulation for LED backlighting

A powering arrangement comprising:

• a plurality of DC/DC converters receiving power from a common power source, each of said plurality of DC/DC converters comprising a first electronically controlled switch;
• a plurality of second electronically controlled switches, each of said second plurality of electronically controlled switches associated with, and arranged in series with, the output of a particular one of said plurality of DC/DC converters and arranged to pulseably enable the flow of current sourced from said particular DC/DC converter through a respective load;
• a plurality of synchronized samplers, each of said plurality of synchronized samplers associated with a particular one of said plurality of second electronically controlled switches and arranged to sample said pulseably enabled current flow and output a sampled representation;
• a plurality of feedback circuits each associated with a particular one of said plurality of synchronized samplers, each of said plurality of feedback circuits arranged to control a respective one of said first electronically controlled switches responsive to said respective sampled representation;
• and
• a plurality of reference voltages, each of said plurality of feedback circuits being further associated with, and responsive to, a particular one of said plurality of reference voltages,
• wherein each of said plurality of feedback circuits comprises a comparing circuit arranged to:
• receive said associated reference voltage and said sampled representation;
• and
• output a compared signal responsive to the difference between said received reference voltage and said received sampled representation,
• said control of said respective one of said first electronically controlled switch being responsive to said compared signal.

A powering arrangement for a plurality of light emitting diode (LED) strings, said powering arrangement comprising:

• a primary side pulse width modulation control circuit;
• a primary side electronically controlled switch responsive to an output of said primary side pulse width modulation control circuit;
• a primary side feedback circuit;
• a transformer exhibiting a primary winding and a plurality of secondary windings coupled to said primary winding, the primary winding connected in series with said primary side electronically controlled switch so as to be switchably coupled across a source of electrical power, wherein electrical power from the source of electrical power is alternately passed through said primary winding and prevented from passing through said primary winding responsive to the respective state of said primary side electronically controlled switch;
• a first plurality of secondary side electronically controlled switches, each of said first plurality of secondary side electronically controlled switches associated with a particular one of said plurality of secondary windings;
• a plurality of LED strings, each of said plurality of LED strings associated with, and arranged to receive power from, a particular one of said plurality of secondary windings responsive to the respective first secondary side electronically controlled switch;
• a second plurality of secondary side electronically controlled switches, each of said second plurality of secondary side electronically controlled switches arranged in series with a particular one of said plurality of LED strings and arranged to pulseably enable the flow of current through said particular LED string;
• a plurality of synchronized samplers, each of said plurality of synchronized samplers in communication with a particular one of said plurality of LED strings and arranged to sample said pulseably enabled current flow and output a sampled representation;
• and
• a plurality of secondary side feedback circuits each associated with a particular one of said plurality of synchronized samplers, each of said plurality of secondary side feedback circuits arranged to control a respective one of said first secondary side electronically controlled switches responsive to said respective sampled representation,
• wherein said primary side feedback circuit is arranged to feedback an output from one of said plurality of secondary windings to a control input of said primary side pulse width modulation control circuit.

A method of powering for a plurality of light emitting diode (LED) strings, said method comprising:

• providing a transformer comprising a primary winding and a plurality of secondary windings;
• providing a primary side controller, said provided primary side controller arranged to switchably control electrical power through the primary winding of the provided transformer;
• providing a plurality of secondary side controllers, the plurality of secondary side controllers less in number than the plurality of secondary windings;
• providing a first plurality of secondary side electronically controlled switches, each associated with a particular secondary winding of the transformer and responsive to the output of a particular one of the provided plurality of secondary side controllers;
• providing the plurality of LED strings, each of the provided plurality of LED strings associated with each of said provided secondary side controllers;
• providing a second plurality of secondary side electronically controlled switches each arranged in series with a particular one of the provided LED strings;
• pulseably enabling current flow through each of said associated provided LED strings by controlling the respective one of the provided second plurality of secondary side electronically controlled switches;
• sampling said pulseably enabled current flow through each of said provided LED strings during said pulseably enabled current flow;
• feeding back a function of each of said sampled pulseably enabled current flows to said associated provided secondary side controller;
• and
• controlling said provided primary side controller responsive to a particular secondary winding of the transformer for which no secondary side controller is provided.