LCD Drive Control Circuit for Correct AVDD AVEE VDDI Sequencing
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Solution Overview
Problem
Liquid crystal display drive modules are prone to damage due to abnormal power sequencing where the AVDD and AVEE signals being powered on or off before the VDDI signal, disrupting the normal operation of the drive chip.
Innovation Solution
A control circuit is implemented to manage the on/off time sequence of multiple power source signals, ensuring the VDDI signal is powered on before and off after the AVDD and AVEE signals, using capacitors and transistors to regulate the input and output of these signals to the drive chip.
Engineering Contradictions & Design Principles
Engineering 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
Solution Approach 1:
The control circuit performs preliminary actions by detecting the power state of VDDI signal in advance and proactively controlling the power sequence of AVDD and AVEE signals. The detection unit monitors VDDI status before power transitions occur, and the control unit pre-establishes the correct power sequence, preventing abnormal power sequencing that could damage the drive chip.
Solution Approach 2:
The control circuit acts as an intermediary between the power supply system and the drive chip. It includes a detection unit that monitors VDDI signal state and a control unit that regulates the power sequencing of AVDD and AVEE signals based on VDDI status, thereby mediating the power supply process to ensure proper sequencing and protect the drive chip from damage.
2Ease of operation
If multiple power source signals are input simultaneously to the drive chip, then the power supply process is simplified, but the normal time sequence between power signals cannot be ensured
Solution Approach 1:
The control circuit implements feedback by continuously detecting the power state of the VDDI signal and adjusting the power sequencing of AVDD and AVEE signals accordingly. The detection unit provides real-time feedback on VDDI status to the control unit, which then regulates the power supply sequence to maintain proper timing relationships despite simultaneous power signal inputs.
3Reliability
If the VDDI signal is not powered on earlier than AVDD and AVEE signals, then the power supply sequence is abnormal, but this disrupts normal drive chip operation
Solution Approach 1:
The control circuit performs preliminary detection of VDDI power state before initiating power transitions for AVDD and AVEE signals. By detecting VDDI status in advance and proactively controlling the power sequence, the circuit ensures VDDI is powered on earlier than AVDD and AVEE, maintaining proper operational stability of the drive chip.
Solution Approach 2:
The control circuit serves as an intermediary that regulates the power sequencing between VDDI, AVDD, and AVEE signals. The detection unit monitors VDDI state and the control unit adjusts the power supply sequence accordingly, ensuring VDDI is powered on earlier than AVDD and AVEE to maintain drive chip operational stability.
Data Source
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.