LIGHT-EMITTING DIODE DRIVING APPARATUS

摘要

Provided is a light-emitting diode driving apparatus, including: a switching transistor which becomes an on-state or an off-state in response to a pulse width modulation signal; a light-emitting diode electrically connected with a second terminal of the switching transistor; a first comparison circuit which outputs a first voltage depending on a comparison result between a first input voltage corresponding to a voltage applied to the light-emitting diode and a first threshold voltage; a second comparison circuit which outputs a second voltage depending on a comparison result between a second input voltage corresponding to a voltage applied to the light-emitting diode and a second threshold voltage; and a signal processing circuit which detects a failure in the light-emitting diode on the basis of an output state of the pulse width modulation signal, the first voltage, the second voltage and a third voltage on the second terminal side of the switching transistor.

主权项

1. A light-emitting diode driving apparatus, comprising:
a switching transistor which has a first terminal electrically connected with a power source and becomes an on-state or an off-state in response to a pulse width modulation signal applied to a control terminal; a light-emitting diode which is electrically connected with a second terminal of the switching transistor and emits light when an electric current flows; a first comparison circuit which is electrically connected between the switching transistor and the light-emitting diode and outputs a first voltage depending on a result of comparison between a first input voltage corresponding to a voltage applied to the light-emitting diode and a first threshold voltage; a second comparison circuit which is electrically connected between the switching transistor and the light-emitting diode and outputs a second voltage depending on a result of comparison between a second input voltage corresponding to a voltage applied to the light-emitting diode and a second threshold voltage different from the first threshold voltage; and a signal processing circuit which detects a failure having occurred in the light-emitting diode on the basis of an output state of the pulse width modulation signal, the first voltage, the second voltage and a third voltage on the second terminal side of the switching transistor.