Gate Driver Current Limit Circuit Reduces EMI
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Solution Overview
Problem
Conventional gate drivers for liquid-crystal display (LCD) panels generate instantaneous peak currents due to sudden resistance changes, leading to electromagnetic interference by emitting electromagnetic waves that affect communication bands.
Innovation Solution
A gate driver with output channel units comprising first and second driving units, and current limit circuits that control output current according to output voltage, limiting the output current slew rate and peak current slew rate to reduce electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MOSFET switch is turned on to drive GOA circuits and multiplexers, then driving ability is easily adjusted, but instantaneous peak current is generated due to sudden resistance change
Solution Approach 1:
The patent applies preliminary action by introducing a current limit circuit that pre-regulates the output current before it reaches the MOSFET switch. The current limit circuit includes a sensing resistor and control transistors that detect and limit the output current in advance, preventing the sudden peak current from occurring when the MOSFET switches on, while still allowing the MOSFET to provide adjustable driving capability.
2Productivity
If instantaneous peak current is generated to charge or discharge resistor-capacitor loops, then switches on the panel can be turned on/off, but electromagnetic waves are generated and emitted around the panel
Solution Approach 1:
The patent converts the harmful instantaneous peak current into a controlled, limited current through the current limit circuit. By using the sensing resistor to detect current levels and the control transistors to regulate them, the circuit transforms what would be harmful electromagnetic-generating peaks into controlled current transitions that still achieve switch toggling but without excessive electromagnetic radiation.
3Object-generated harmful factors
If current limit circuit is added to control output current, then output current slew rate is limited and electromagnetic interference is reduced, but device complexity increases
Solution Approach 1:
The patent merges the current limit circuit with the existing MOSFET driver structure. The current limit circuit shares the output node and control signals with the MOSFET driver, and the sensing resistor is integrated into the existing current path. This merging approach allows current limiting functionality to be added without requiring completely separate control circuits, thereby reducing the overall complexity increase.
Data Source
AI summary
A gate driver for a panel, wherein the gate driver comprises at least an output channel unit, each of the output channel unit includes a first driving unit; a second driving unit; a first current limit circuit, coupled to the first driving unit, configured to control an output current according to an output voltage of the gate driver to limit an output current slew rate of the gate driver; and a second current limit circuit, coupled to the second driving unit, configured to control the output current according to the output voltage of the gate driver to limit the output current slew rate of the gate driver.