Design of a High-Power LED Constant Current Drive Chip

A 4 W LED constant-current driving integrated circuit is designed. The driver has a simple structure and can provide a stable constant current of 350 mA for LED devices. When the power supply voltage fluctuates within ±10%, the output driving current changes less than 5%. When the temperature varies between 0°C and 120°C, the change in output driving current is less than 5%. The control circuit consists of a bandgap voltage reference, an error amplifier, a sampling circuit, a negative feedback circuit, and a mirror current source. The bandgap voltage reference provides two reference voltages that are independent of temperature and power supply voltage in the system. The sampling circuit and operational amplifier form a negative feedback circuit, allowing the sampling NMOS and power driven NMOS to operate at the same temperature and current density, so that the sampling current can more accurately reflect the changes in the output driving current of the power driven NMOS, and improve the control accuracy of the output driving current.