LED driver with precharge and track/hold

Details LED driver with precharge and track/hold LED driver with precharge and track/hold

2011-08-23

2011-08-23

Tran, Anh Q (Department: 2819)

Electric lamp and discharge devices: systems

Current and/or voltage regulation

C315S18500S, C315S18500S, C315S307000

Reexamination Certificate

active

08004207

ABSTRACT:
A power source provides an output voltage to drive a plurality of light emitting diode (LED) strings. A feedback controller monitors the tail voltages of the LED strings to identify the minimum tail voltage and adjusts the output voltage based on a relationship between the minimum tail voltage and a reference voltage. The feedback controller implements precharging of the output voltage, including one or both of short-term precharging or long-term precharging. Further, the feedback controller incorporates a track/hold circuit that tracks the minimum tail voltage while the LED strings are active and holds the minimum tail voltage at the last tracked minimum tail voltage while the LED strings are inactive and uses the held minimum tail voltage for controlling the output voltage while the LED strings are inactive so as to permit the power source to supply an appropriate output voltage when the LED strings are subsequently activated again.

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