A new low voltage detecting method for multi-string LED BLU circuit

This paper proposes a new lowest-voltage detecting circuit for multi-channel LED backlighting units (BLUs) for LCD TVs. The proposed circuit detects the lowest voltage drop among the multi-channel LED strings with reduced number of devices. After detecting such condition the circuit provides a feedback voltage to control the output voltage of the boost converter. Therefore, it can minimize the power losses in LED driving circuit. Experimental results are presented for a 15 W boost converter driving 40 mA, 8-channel LED strings.