The Design Of LED Control Chip With I~2C Interface

With the development of semiconductor technology,light-emitting diodes have only been spent a few decades to popularize around the world.With the characteristics of high durability,good stability,fast response,and low energy consumption and environmental protection,LED gradually replaced the traditional lighting sources and play an important role in the lighting industry.Compared with incandescent lamps and fluorescent lamps in the past,LED has a remarkable improvement in work efficiency,and is to adapt to more lighting environments by using a driving circuit.Under the background of LED's huge market potential,based on the GSMC0.18?m digital-analog CMOS technique,this paper designed a LED driver with I~2C connector.The chip is controlled by I~2C-bus and can drive 16 LEDs'output at the same time.Each LED output has its own 8-bit resolution fixed frequency individual PWM controller.An additional 8-bit resolution(256 steps)group PWM controller is used to either dim or blink all LEDs with the same value.According to the functional requirements of the chip,the design task is divided into five modules:I~2C control module,oscillation frequency division module,group pulse width modulation module,independent pulse width modulation module,and output module.The I~2C control module includes a condition judgment circuit,an address selection circuit,a data storage circuit,and a protection circuit,which is responsible for receiving,decoding and transmitting the I~2C signal.The frequency dividing module is designed with the principle of the synchronous frequency dividing circuit,and provides eight clocks for the internal circuit.The output module is mainly composed of state selection circuits and outputs driving signals.The independent pulse width modulation module and the group pulse width modulation module are mainly composed of pulse width modulation circuits.The duty of the driving signal is controlled by combinational logic gate circuits and triggers.In comparison,the group pulse width modulation module also has a frequency modulation module that can regulate the frequency of the driving signal.Each module uses Verilog to finish the RTL-level design and switch-level design,and then perform the digital simulation.After the verification,each module is integrated by the top modul.Input the I~2C excitation signal to perform overall digital simulation.Observe the status of the drive signal from the LED output,and calculate the duty cycle of the signal.Make sure that duty cycle can be adjusted from 0%to 99.6%.The simulation result is correct.Finally,based on the Virtuoso tool,the switching level design of the circuit is performed.Add protection circuits for I~2C interfaces to reduce noise interference.The simulation platform was set up to simulate the digital-analog simulation with the supply voltage of 5V and the temperature range of-40°C to 85°C.Observe the state of the drive signal from LED outputs that the drive signal can be the shutdown signal,the fully on signal,and the PWM signal in which the duty cycle can be adjusted from 0%to 99.6%.The simulation result is correct and the circuit satisfies the design requirements.