Voltage Level Translator Circuit That Keeps the Pass Switch Off
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Solution Overview
Problem
Existing level translation circuits fail to maintain the pass switch in an off state when power supply is zero or very low, leading to potential malfunction due to higher port voltages causing the pass switch to turn on.
Innovation Solution
A circuit that evaluates the difference between port voltages and the pass switch voltage, ensuring the pass switch remains off by selecting the higher voltage to control the pass switch, keeping the gate voltage lower or equal to the port voltages, thus maintaining the off condition regardless of port voltages or power supply levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power supply to the pass switch is zero or very low, then power dissipation is reduced, but higher potentials at the ports may cause the pass switch to turn on causing malfunction
Solution Approach 1:
The patent introduces a control circuit as an intermediary between the power supply and the pass switch gate. This control circuit monitors both the power supply voltage and port voltages, and only enables the pass switch when appropriate voltage conditions are met. The intermediary control logic prevents direct connection issues by mediating the switch state based on voltage relationships, thus maintaining reliability while allowing power supply to reach zero or very low levels.
2Device complexity
If the pass switch is controlled by simple power supply voltage, then device complexity is reduced, but the pass switch may turn on improperly when port voltages exceed power supply voltage
Solution Approach 1:
The patent implements dynamic control of the pass switch by making the gate voltage dependent on both the power supply voltage and the port voltages. The control circuit dynamically adjusts the switch state based on real-time voltage conditions, transitioning from a static control approach to a dynamic one. This allows the system to adapt to varying voltage conditions and prevent improper switch activation while maintaining reasonable circuit complexity through efficient logic design.
Data Source
AI summary
A circuit is described that when the power supply to circuits that control a pass transistor is at zero volts, the pass transistor configured as a voltage level translator remains off regardless of the voltages and changes in voltages at the ports connected to the pass transistor. Cross coupled transistors provide a mechanism where the higher of the port voltages is available to power circuitry that maintains the control input of the pass transistor in the off condition. The voltages at the ports may rise and fall relative to each other, but the control input of the pass transistor will keep the pass transistor off.