Source Driver Data Switching to Reduce Complementary Peak Current
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Solution Overview
Problem
Conventional source drivers experience instantaneous peak currents when new pixel data complements old data, leading to voltage drops and electromagnetic interference, which disrupt normal operation and cause system instability.
Innovation Solution
A source driver incorporating a latch circuit, level shifter, and digital-to-analog converter (DAC) circuit that compares current and previous bit-data, selecting and outputting either the current or previous bit-data to the level shifter based on complementarity, thereby reducing peak current by maintaining stable voltage levels during data transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the latch circuit updates new pixel data in parallel according to the rising time point of the latch signal, then the data update speed is improved, but an instantaneous peak current is generated when the new pixel data is the complement of the old pixel data
Solution Approach 1:
The patent applies preliminary action by comparing the current pixel data with the previous pixel data before the data is latched and processed. The comparison result is used to control the selection of current data or previous data, preventing the instantaneous peak current from occurring in the first place. This pre-comparison mechanism allows the system to prepare the appropriate data state before the actual data update, thereby maintaining fast update speed while avoiding harmful peak currents.
2Ease of operation
If the instantaneous peak current occurs when new pixel data is the complement of old pixel data, then the data processing function is maintained, but the voltage level of the power supply voltage drops and electromagnetic interference is generated
Solution Approach 1:
The patent introduces an intermediary mechanism - the comparison circuit and control logic that mediates between the data processing function and the power supply stability. By comparing current and previous data and using the comparison result to control data selection, the system acts as an intermediary that prevents the direct transition to complementary states that cause peak currents. This intermediary control maintains the data processing function while filtering out the harmful voltage drops and electromagnetic interference.
3Productivity
If the current bit-data is always selected and output to the level shifter, then the data processing speed is maintained, but the instantaneous peak current cannot be reduced when complement data is input
Solution Approach 1:
The patent applies preliminary action by performing a comparison between current and previous bit-data before the data is output to the level shifter. This pre-comparison allows the system to determine in advance whether outputting the current data would cause a peak current condition. Based on this preliminary assessment, the control logic selectively outputs either the current data or the previous data, thereby maintaining high data processing speed while preventing instantaneous peak currents from occurring.
Data Source
AI summary
A source driver and a method to reduce peak current of the source driver are provided. The source driver includes a latch circuit, a level shifter and a digital-to-analog converter (DAC) circuit. The latch circuit latches current bit-data. The latch circuit is coupled to an input terminal of the level shifter. The DAC circuit is coupled to an output terminal of the level shifter. When the current bit-data is not a complement of previous bit-data, the latch circuit selects and outputs the current bit-data to the input terminal of the level shifter, and the DAC circuit outputs a voltage corresponding to the output data of the level shifter. When the current bit-data is the complement of the previous bit-data, the latch circuit selects and outputs the previous bit-data to the input terminal of the level shifter, and the DAC circuit outputs a voltage corresponding to the current bit-data.