Over-current Protection Circuit for LCD Drive ICs
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Solution Overview
Problem
In LCD drive systems, the increased screen resolution and drive current specifications lead to potential damage from continuous large currents flowing through drive ICs during assembly, necessitating an over-current protection mechanism to prevent component damage.
Innovation Solution
An over-current protection circuit is implemented, comprising a comparison module to detect output stage currents of operational amplifiers and a delay module to determine if the current exceeds a protection threshold for a preset time, triggering an over-current protection signal to turn off the corresponding circuit block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the drive current specification is increased to meet higher screen resolution requirements, then the drive capability is improved, but the risk of component damage from continuous large current increases
Solution Approach 1:
The protection circuit performs preliminary detection of output stage current before damage occurs. The comparison module continuously monitors the current and compares it against a predetermined threshold, enabling early detection of over-current conditions before they cause component damage.
Solution Approach 2:
The protection circuit acts as an intermediary between the operational amplifier and potential damage. It inserts monitoring and control functionality into the circuit path, using sampling resistors to detect current and a delay module to coordinate the protection response, thereby protecting the operational amplifier from direct damage.
2Reliability
If over-current protection detection is implemented immediately, then component protection is improved, but false triggering due to transient current increases occurs
Solution Approach 1:
The protection circuit uses periodic sampling and time-based filtering to distinguish between transient and sustained over-current conditions. The delay module requires the over-current condition to persist for a predetermined time period before triggering protection, effectively filtering out transient spikes while maintaining protection against sustained over-current.
Solution Approach 2:
The delay module performs preliminary time-based verification before activating protection. By requiring the over-current condition to persist for a predetermined time period, it preliminarily filters out transient conditions that would cause false triggering while still detecting genuine over-current threats.
3Measurement precision
If continuous current monitoring is implemented, then over-current detection capability is improved, but circuit complexity increases
Solution Approach 1:
The protection circuit segments the current monitoring function into distinct modular components: sampling resistors for current detection, a comparison module for threshold evaluation, and a delay module for time-based filtering. This segmentation allows each component to perform its specific function efficiently while keeping the overall circuit design manageable and systematic.
Solution Approach 2:
The circuit uses intermediary elements such as sampling resistors that convert current measurements into voltage signals suitable for comparison, and a delay module that mediates between immediate detection and protection activation. These intermediaries simplify the overall detection logic while maintaining precise monitoring capability.
Data Source
AI summary
Disclosed is an over-current protection circuit, an over-current protection method and a display device. The over-current protection circuit provides an over-current protection for an operational amplifier and the over-current protection circuit comprises: a comparison module to compare a reference voltage and an output stage current sampling signal of the operational amplifier to determine whether an output stage current of the operational amplifier exceeds a protection threshold; a delay module to determine whether the output stage current of the operational amplifier exceeds the protection threshold for a time that reaches a preset time threshold, and output an over-current protection signal to turn off the operational amplifier when the output stage current of the operational amplifier exceeds the protection threshold for a time that reaches the preset time threshold. The present disclosure can effectively prevent the drive IC from being damaged by the continuous large current flowing through the drive IC.