A single inductor multiple LED string driver comprises a switch control circuit and a current-sensing control circuit. The predetermined number of sequences are grouped by partitioning the predetermined number of sequences, in which sequences generated from the same base sequence and having different cyclic shifts are arranged in an increasing order of the cyclic shifts. A column address that identifies data sensed is latched using the plurality of sense amplifiers. If the ventricular intervals corresponding to the tachycardia are increased in response to delivering stimulation pulses to the cardiac neural tissue, the tachycardia is detected as a supraventricular tachycardia.