Display Driver Output Circuit Low-Voltage Switching
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Solution Overview
Problem
Display driving devices face challenges in achieving low power consumption and stable electrical characteristics due to the high voltage requirements of output circuits, which lead to inefficiencies and increased power consumption, and the inability to maintain a consistent electrical environment between output buffer units and switching units.
Innovation Solution
The implementation of an output circuit and switching circuit that utilize low-voltage transistors driven by a middle voltage between the pull-up and pull-down voltages of the output buffer unit, allowing for direct and cross-path signal transmission and charge-sharing, thereby eliminating the need for high-voltage switching elements and ensuring a stable electrical environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the output circuit is driven by a high voltage, then the output circuit can provide sufficient driving capability to the display panel, but the power consumption increases significantly
Solution Approach 1:
The output circuit is divided into two distinct parts: an output buffer unit that operates at high voltage to provide driving capability, and a switching unit that operates at low voltage to reduce power consumption. This segmentation allows each part to operate at its optimal voltage level, resolving the contradiction between driving capability and power consumption.
Solution Approach 2:
Different voltage levels are applied to different parts of the circuit based on their specific functional requirements. The output buffer unit uses high voltage for sufficient driving capability, while the switching unit uses low voltage for reduced power consumption. This local differentiation of voltage quality optimizes overall system performance.
2Productivity
If the output buffer unit and switching unit have different driving voltage ranges, then each unit can be optimized for its function, but the electrical characteristic becomes unstable
Solution Approach 1:
A voltage conversion circuit is introduced as an intermediary between the low-voltage switching unit and the high-voltage output buffer unit. This intermediary converts the low-voltage control signals from the switching unit into high-voltage signals that can drive the output buffer, enabling functional optimization while maintaining electrical characteristic stability through proper voltage level translation.
3Reliability
If high-voltage switching elements are used in the switching unit, then the circuit can handle high voltage signals, but the power consumption increases and process cost increases
Solution Approach 1:
The circuit is segmented into voltage domains, with the switching unit operating exclusively in the low-voltage domain for power-efficient signal routing decisions, while only the output buffer unit operates in the high-voltage domain for actual panel driving. This eliminates the need for high-voltage switching elements in the switching unit.
Solution Approach 2:
The voltage parameter is changed from high voltage to low voltage for the switching unit operations. By performing switching operations at low voltage levels and only transitioning to high voltage at the output buffer stage, the circuit achieves reliable signal routing without the power consumption and cost penalties of high-voltage switching elements.
Data Source
AI summary
An output circuit of a display driving device may include: an output buffer unit configured to buffer a pair of input signals having different polarities and output a pair of output signals; and a switching unit configured to transmit the pair of output signals to a pair of output terminals through a direct path or a cross path during an output period, and charge-share the pair of output terminals using a middle voltage of a pull-up voltage and a pull-down voltage of the output buffer unit during a charge-sharing period.