[mu] LED current mode pixel driving circuit system

Abstract

The invention provides a [mu] LED current mode pixel driving circuit system. The system comprises a reference current generating circuit, a pixel current driving unit, an 8-bit SRAM unit, a counter and a comparator. The pixel current driving unit comprises a cascade current mirror circuit and a switch control tube; and the current of the cascade current mirror circuit is kept the same as the current of the reference current generating circuit. The comparator compares data stored in the 8-bit SRAM unit with data of the counter, and converts an 8-bit pixel grayscale signal into a PWM signal; andthe switch control tube is controlled through the PWM signal, so that the brightness of a [mu] LED is controlled by a PWM current. The constant current of the reference current generating circuit canbe accurately copied to the cascade current mirror circuit, and the on-off time of the switch control tube is controlled by the PWM signal generated by the comparator, so that the pulse modulation ofthe current is realized, the problems that the control difficulty of the display brightness of a display is increased and the display is not uniform due to a traditional voltage control circuit are improved, and better display effect and contrast can be obtained.

Description

technical field [0001] The invention relates to the technical field of driving circuits, in particular to a μLED current mode pixel driving circuit system. Background technique [0002] The LED drive power supply is a power converter that converts the power supply into a specific voltage and current to drive the LED to emit light. Most of the output of the LED drive power supply is a constant current source that can change the voltage with the change of the LED forward voltage drop value. There are two common driving methods, one is a constant voltage source for multiple constant current sources, and each constant current source supplies power to each LED separately. This combination is flexible, when one LED fails, it will not affect the work of other LEDs. [0003] The driving methods include constant current type, voltage regulator type, pulse drive and so on. The output current of the constant current drive circuit is constant, but the output DC voltage varies within ...

AI Technical Summary

Problems solved by technology

[0005] However, in the traditional LED constant current control method, the constant current used is usually directly connected to the LED, resulting in unavoidable fluctuations or even large fluctuations in the current of the LED during operation, which will lead to difficult control of the brightness of the display and uneven problems.

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