Design and implement of LED drive circuit chip with the controllable constant output current

• 作 者: 李先锐 王松林 来新泉 李玉山
• 机 构: Institute of Circuit Design,Xi\'an University of Electronic Science and Technology,School of Elect
• 出 处: Optoelectronics Letters
• 发表日期: 2009年03期
• 关键词: controllable amplifier offset driver stored connected have belongs switch drivin

Owing to the fact that the LED drive circuit must have constant output current control,we propose a controlled current driver with a high precision for the white light LED.Three discrete constant current settings are available and may be selected at the supply voltage from 2.9 V to 4.4 V,which is up to 1 A.An autozero transconductance amplifier is proposed,which effectively improves the precision,reduces the offset voltage and the noise.The variation in the ratio of the external resistor current to the LED load current is less than 2.3%,when the LED load current changes from 200 mA to 800 mA.

Owing to the fact that the LED drive circuit must have constant output current control, we propose a controlled current driver with a high precision for the white light LED. Three discrete constant current settings are available and may be selected at the supply voltage from 2.9 V to 4.4 V, which is up to 1 A.An autozero transconductance amplifier is proposed, which effectively improves the precision, reduces the offset voltage and the noise. variation in the ratio of the external resistor current to the LED load current is less than than 2.3% when the LED load current changes from 200 mA to 800 mA.