| 摘要 |
An LED driver includes a current sink positioned to control the flow of current between a battery and an LED. The LED driver also includes a charge pump. A control circuit monitors the forward voltage of the LED. A second voltage (V<SUB>TRIP</SUB>) is derived to predict the voltage required to operate the current sink. Battery mode operation is used whenever the battery voltage is sufficient to supply the combination of the V<SUB>TRIP </SUB>voltage, the LED forward voltage and a small safety margin. Charge pump mode operation is used in all other cases. The selection between battery mode and charge pump mode is dynamic, reflecting the battery's current output level as well as the brightness level of the LED.
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