Adjustable constant flow source driving circuit for LED

The invention discloses an adjustable constant flow source driving circuit for an LED (light-emitting diode). The driving circuit comprises an operation amplifier, a transistor and a single chip system, wherein the positive phase input end of the operation amplifier is connected with a reference voltage circuit, the grid electrode of the transistor is coupled with the output end of the operation amplifier through a resistor R4, the LED is connected between the drain electrode of the transistor and the reference voltage circuit, the single chip system is connected with the positive phase input end of the operation amplifier, the source electrode of the transistor is connected with the negative phase input end of the operation amplifier to form a current-series negative feed-back system, a grounded voltage sampling resistor R6 is connected between the source electrode of the transistor and the negative phase input end of the operation amplifier, nodes A are formed between the source electrode of the transistor and a voltage sampling resistor R6, the single chip system is used for adjusting the control voltage of the positive phase input end of the operation amplifier according to the voltage signals acquired from the nodes A, and a grounded divider resistor R5 is connected between the resistor R4 and the grid electrode of the transistor. The driving circuit is controlled by the single chip system, thus current change can be steadily and continuously controlled when the voltage on the positive phase input end of the operation amplifier is adjusted.