| 摘要 |
PURPOSE: A constant current supply circuit is provided to prevent current deviation between LEDs while using a regulator and also to prevent excessive battery use while using a charge pump. CONSTITUTION: An enable switch(210) switches a path to a ground according to an enable signal. A control signal generation unit(220) generates a control signal according to a differential component of the first voltage level and the second voltage level. A control switch(230) is connected to the enable switch serially, and switches a path to the enable switch according to the control signal. A power supply(240) supplies a supply voltage. A current adjustment switch group(250) includes a plurality of transistor switches, and provides a plurality of currents according to the control of the control switch. An LED group(260) includes a plurality of LEDs, and radiates through a current supplied from the current adjustment switch group, and applies a voltage of the first voltage level to the control signal generation unit.
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