Negative Voltage Tolerant IO Circuitry Protection
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Solution Overview
Problem
Integrated circuit IO pads face damage from negative voltages applied during power factor correction, which can damage transistors and render the IO pad inoperable, affecting the functionality of electronic devices.
Innovation Solution
The implementation of a receiver protection circuit and a transmitter protection circuit that decouples the IO node from the receiver circuit and applies negative voltages to a device terminal within the transmitter driver circuit, using n-channel and p-channel transistors, including DMOS devices, to prevent damage, along with a control voltage generation circuit to manage these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power factor correction circuitry is used to control power consumption, then power factor is improved, but negative voltages are applied to the IO pad causing damage to transistors
Solution Approach 1:
The patent introduces protection circuitry as an intermediary between the power factor correction circuitry and the IO pad. This intermediary includes detection circuits that sense negative voltages and activation circuits that respond by protecting the transistors, thereby allowing power factor correction to function while preventing damage to the IO pad components
Solution Approach 2:
The protection mechanism applies preliminary anti-action by detecting the presence of negative voltages before they can cause damage to the transistors. The detection circuit identifies negative voltage conditions and triggers protective measures in advance, preventing the harmful effect from manifesting while allowing the power factor correction to continue operating
2Reliability
If protection circuits are added to protect against negative voltages, then reliability is improved, but device complexity increases
Solution Approach 1:
The protection circuitry is merged with the existing IO pad structure rather than being completely separate. The detection and protection functions are integrated into the same circuit block, sharing common elements with the transmitter and receiver circuits, thereby providing protection while minimizing the increase in overall device complexity
Solution Approach 2:
The protection circuit is designed to be self-activating through automatic detection of negative voltage conditions. The detection circuit automatically senses when negative voltages appear and triggers the protection mechanism without requiring external control signals, thereby simplifying the overall control structure while maintaining reliability
Data Source
AI summary
Disclosed herein is an electronic device including an IO node, with a receiver coupled to receive input from the IO node. A transmitter driver has a first n-channel DMOS with a source coupled to the IO node. A pass gate circuit decouples the IO node from the receiver based upon presence of a negative voltage at the IO node and couples the IO node to the receiver based upon lack of presence of the negative voltage at the IO node. A transmit protection circuit applies the negative voltage from the IO node to the gate and bulk of the first n-channel DMOS based upon the presence of the negative voltage at the IO node.