Single string over power protection and light source driver circuit used in display device

摘要

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.

主权项

1. A single-string over power protection device for a display, comprising:
a voltage detection unit, with an input terminal being connected to a voltage acquisition component in the circuit of a single-string light bar at both ends, for obtaining the voltage across the voltage acquisition component; 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 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 an output standby signal according to the effective over voltage signal, wherein the latch unit comprises a first transistor and a second transistor, a base of the first transistor is connected to both the output terminal of the comparison unit and the collector of the second transistor, the collector of the first transistor is connected to a base of the second transistor, and an emitter of the second transistor is connected to a power Vcc terminal via a pull-up resistor.