Gamma voltage output circuit based on digital PMIC

Abstract

The invention relates to a gamma voltage output circuit based on a digital PMIC (Power Management Integrated Circuit). An analog voltage (AVDD) is input to a GLDO module and a comparator, and the GLDOmodule outputs a first gamma reference voltage (Vref1) to the comparator and an either-or selector. A second gamma reference voltage (Vref2) is input to the either-or selector, and the second gamma reference voltage (Vref2) is greater than or equal to a set value of gamma reference voltage (Vref). When the analog voltage (AVDD) is greater than the first gamma reference voltage (Vref1), the comparator makes the either-or selector output the first gamma reference voltage (Vref1) as the gamma reference voltage (Vref). When the analog voltage (AVDD) is smaller than the first gamma reference voltage (Vref1), the second gamma reference voltage (Vref2) is output. The gamma reference voltage (Vref) is output to a gamma correction module, and the gamma correction module outputs a gamma voltage. According to the circuit of the invention, when the analog voltage and the gamma reference voltage are set wrongly in a register, the gamma voltage will not be abnormal, and the display of the picture will not be abnormal.

Description

technical field [0001] The invention relates to the field of liquid crystal displays, in particular to a digital PMIC-based gamma voltage output circuit. Background technique [0002] Digital power management integrated circuit (Digital PMIC) is a circuit commonly used in liquid crystal display drivers. Such as figure 1 As shown, it is an internal block diagram of the gamma (Gamma) voltage and gamma reference voltage Vref in the existing digital PMIC, showing the part related to the gamma voltage output in the digital PMIC, mainly including registers, digital Analog-to-analog converter (DAC), GLDO (low dropout linear regulator) module, gamma correction module. The data input from the data line SDA and the clock signal line SCL of the I2C bus are stored in the register, and the digital signal output by the register is converted into an analog signal by a digital-to-analog converter, and then the analog signal is input into the GLDO module and the gamma correction module. Th...

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Problems solved by technology

[0004] Therefore, the object of the present invention is to provide a kind of gamma voltage output circuit based on digital PMIC, solve the problem that analog voltage AVDD and gamma reference voltage Vref are wrongly set in register and cause gamma voltage to output abnormally

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