Constant current drive for LED light source

A constant current driver for an LED light source, comprising a main power supply loop and at least one backup power supply loop, wherein the main power supply loop at least comprises a power conversion circuit, the power conversion circuit outputs a constant current to the LED light source;

• the backup power supply loop at least comprises a backup power conversion circuit, the backup power conversion circuit outputs a constant current to the LED light source;
• when the power conversion circuit and the backup power conversion circuit are operated normally, each one of the power conversion circuit and the backup power conversion circuit is operated in a rated state or a derated state, and an output terminal of the power conversion circuit and an output terminal of the backup power conversion circuit are connected in parallel to supply power to the LED light source simultaneously;
• and
• when any one of the power conversion circuit and the backup power conversion circuit becomes invalid, the invalid circuit does not affect the normal operation of the remaining circuit;
• wherein when the setting operating current of at least one of the power conversion circuit and the backup power conversion circuit is lower than its own rated operating current, the constant current driver further comprises a current regulation circuit adapted to output a signal to the remaining circuit and increase output current of the remaining circuit, when it is determined that one of the power conversion circuit and the backup power conversion circuit is invalid.