Dynamic current limitation circuit for white LED driver

In this paper, we propose a dynamic current limitation circuit which can adjust the driverpsilas output current corresponding to the white LEDpsilas current-temperature curve. Its topology is based on PTAT and CTAT current generator, and it can detect the safe threshold temperature T_th0 which is decided by the maximum allowable forward-current of white LED. Moreover, when temperature rises above T_th0, the circuit also can adjust the driverpsilas output current corresponding with the exact slope of the current-temperature curve. By adopting this circuit, the white LED driver can acquire the maximum safe output current within wide temperature range. Such driver is implemented by BCD 0.5 mum process. And the simulation results show that when temperature varies in the range of -25degC~85degC, the circuit can precisely detect the threshold temperature and promptly regulate the output current according to the white LEDpsilas current-temperature curve.