Low Power Transistor EOS Protection Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In high-voltage applications, existing voltage regulators consume high power and are not suitable for low power applications, and they require EOS protection to prevent transistor exposure to higher power supplies, leading to increased costs and reliability challenges due to the need for multiple types of transistors with different gate-oxide thicknesses.
Innovation Solution
A low-power circuit comprising a voltage detector and a supply switching circuit that generates a local supply to control the gate terminal of a pass-gate, allowing 1.8V transistors to support both 1.8V and 3.3V applications, reducing the need for special high-voltage tolerant transistors and minimizing idle power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage regulators are used to generate intermediate-level voltage for EOS protection, then transistor protection from electrical overstress is improved, but power consumption increases and idle power is consumed
Solution Approach 1:
The protection circuit uses the existing power supply voltages (V1 and V2) to automatically generate the appropriate gate voltages for pass-gates without requiring external voltage regulators. The circuit self-regulates by detecting which power supply is active and generating corresponding protection voltages, eliminating continuous power consumption associated with voltage regulators.
Solution Approach 2:
The circuit activates protection mechanisms only when needed - specifically when power supplies are ramping up or down. The control circuit detects power supply states and enables protection pass-gates during critical transitions, then disables them during stable operation, converting continuous protection into periodic, event-driven protection that consumes minimal power.
2Adaptability or versatility
If multiple types of transistors with different gate-oxide thicknesses are used to support different voltage levels, then voltage support capability is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The protection circuit enables universal use of a single transistor type (with gate-oxide thickness optimized for lower voltage) across multiple voltage levels. By adding protection pass-gates that block excessive voltage, the same transistor can safely operate in both low-voltage (1.8V) and high-voltage (3.3V) circuits, eliminating the need for separate high-voltage transistor types.
Solution Approach 2:
The protection pass-gates act as intermediaries between the transistor and high-voltage power supplies. These pass-gates control the voltage exposure to transistors, allowing transistors to be connected to high-voltage supplies only when protected, thus enabling voltage adaptability without requiring physically different transistor structures.
3Reliability
If intermediate-level voltage is generated to protect transistors during power supply ramping, then transistor junction breakdown is prevented, but additional circuit complexity and EOS protection requirements are introduced
Solution Approach 1:
The protection functionality is merged with the existing power supply ramping control logic. The same control circuit that manages power supply sequencing also generates protection voltages for pass-gates, combining two functions into one circuit block and avoiding additional dedicated protection circuits.
Solution Approach 2:
The protection pass-gates are enabled in advance before transistors are exposed to potentially damaging voltages during power supply ramping. The control circuit detects the ramping state and activates protection mechanisms proactively, preventing junction breakdown before it can occur rather than responding after damage happens.
Data Source
AI summary
Described is an apparatus which comprises a pass-gate; and a control unit to control gate terminal of the pass-gate according to first availability of first or second power supplies, the control unit including: a voltage detector to detect the second power supply; and a supply switching circuit to generate a local supply for controlling the gate terminal of the pass-gate according to an output of the voltage detector.