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

Abstract

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.

Keywords

Reference Voltage / External Resistor / Bias Circuit / Lead Load / White Light Lead

References

[1] PiaoY., WangR.-g., DingT.-fu.. Journal of Optoelectronics · Laser, 2008, 19: 125

[2] ZhaoH., XuW.-h., LuY.-j.. Journal of Optoelectronics · Laser, 2007, 18: 1314

[3] WangH., WangS.-l., LaiX.-q.. Journal of Xi’an University, 2008, 35: 272

[4] WangH., WangS., LaiX.. Microeletronics, 2003, 35: 415

[5] C. Enz, and G. Temes, Proceedings of the IEEE, 1996.

[6] Danchiv, BodeaM., DanC.. International Semiconductor Conference, 2006, 2: 409

[7] Razavi B. Design of analog CMOS integrated Circuit. Translated by Chen Guican, Cheg Jun, and Zhang Ruizhi, Xi’an Jiaotong University Press, 2003.