Two-stage brightness control circuit of vehicle-mounted sound equipment product

The invention discloses a two-stage brightness control circuit of a vehicle-mounted sound equipment product, which comprises a display screen backlight LED 15, a first interface of the display screen backlight LED 15 is connected with a resistor R19, and the other end of the resistor R19 is connected with a power supply POW-ON9V; a second interface of a display screen backlight LED 15 is connected with a resistor R23, a triode Q3 is connected in parallel on a connecting line of the resistor R23 and the display screen backlight LED 15, a base electrode of the triode Q3 is connected with a resistor R2, and the other end of the resistor R2 is connected with a B2 pin of the single-chip microcomputer GP. And a resistor R is connected in parallel with a connecting line of the resistor R2 and the triode Q3. According to the circuit, the characteristic that the conduction internal resistance of the triode Q3 is very small is utilized, the collector of the triode Q3 is connected to the two ends of the resistor R23 in