The present disclosure provides a single-string light bar over power protection device and a light source driver circuit for a display. The over power protection device comprises: a voltage detection unit, with an input terminal being connected to a resistor in the circuit of a single-string light bar at both ends, for obtaining the voltage across the resistor; an integral unit, with an input terminal being connected to the output terminal of the voltage detection unit, for performing an integral transform on the voltage obtained; a comparison unit, which is connected to the output terminal of the integral unit, for comparing the voltage after the integral transform with a reference voltage determined by the system parameters, so as to output an effective over voltage signal when the voltage after the integral transform is higher than the reference voltage; and a latch unit connected to the comparison unit to lock the output standby signal according to the effective over voltage signal. The protection device according to the present disclosure can avoid overheat caused by over current of the single-string light bar, and further refrain from abnormality to the whole backlight module, and thus providing better protection for the LCD display.