LCD Drive Control Circuit for Safe AVDD AVEE Power Sequencing

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Solution Overview

Problem

Existing liquid crystal display technologies face a high probability of damaging the drive chip due to abnormal power sequencing, where the AVDD and AVEE signals are powered on or off before the VDDI signal, leading to potential damage.

Innovation Solution

A control circuit is designed to manage the time sequence of power source signals, ensuring the normal sequence by controlling the input and output of VDDI, AVDD, and AVEE signals to the drive chip using capacitors and transistors, thereby reducing the risk of damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the AVDD and AVEE signals are powered on or off before the VDDI signal, then the power supply sequence is abnormal, but this causes damage to the drive chip

Engineering Contradiction:

Improvedrive chip protectionVSAvoidpower control circuit

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control circuit performs preliminary actions by detecting the power state of VDDI signal in advance and generating control signals (GS1, GS2) before the power-on or power-off sequence occurs. This allows the circuit to preemptively prevent abnormal power sequencing that could damage the drive chip, rather than reacting after damage occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit acts as an intermediary between the power supply signals (VDDI, AVDD, AVEE) and the drive chip. It monitors the VDDI signal state and uses control signals (GS1, GS2) to mediate and regulate the power-on/power-off sequences of AVDD and AVEE, ensuring proper sequencing without directly connecting the power signals to the chip.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If simple power control is used without sequence management, then the circuit is simple, but the drive chip is highly susceptible to damage from abnormal power sequencing

Engineering Contradiction:

Improvepower sequencing controlVSAvoidcontrol circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control circuit performs self-service by autonomously detecting the VDDI signal state and automatically generating the appropriate control signals (GS1, GS2) without external intervention. The circuit monitors itself and regulates the power sequencing independently, ensuring reliable operation while maintaining a relatively simple structure.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The control circuit implements feedback by continuously monitoring the state of the VDDI signal and using this information to dynamically adjust the control signals (GS1, GS2) that regulate the power-on and power-off sequences. This closed-loop feedback mechanism ensures proper power sequencing while keeping the circuit design compact and efficient.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3882903B1Control circuit, liquid crystal display driving module, and liquid crystal display device

Publication Date: 2025.12.03 VIVO MOBILE COMM CO LTD

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AI summary

A control circuit, a liquid crystal display drive module, and a liquid crystal display apparatus are disclosed. The control circuit includes: a first input end (101) and a second input end (102) that separately receive different external power source signals, and the control circuit sequentially controls the first input end (101) and the second input end (102) to input a power source signal to the drive chip, and sequentially controls the second input end (102) and the first input end (101) to power off.