eFuse Protection Circuit Preventing False Programming
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Solution Overview
Problem
Conventional electronically programmable fuses (eFuses) are at risk of accidental programming during power-up and electrostatic discharge (ESD) events due to undefined states in control circuitry, leading to unwanted programming.
Innovation Solution
A protection circuit that disables the programming supply during ESD events and power-up, using an ESD trigger signal and a control VDD ON/OFF detection circuit to prevent false programming by ensuring the programming supply is not active during these conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If eFuse programming is enabled during power-up or ESD events, then programming operations can be performed, but false programming occurs due to undefined control circuit states
Solution Approach 1:
The protection circuit proactively disables the programming supply before ESD events or power-up transients can cause undefined control circuit states. By detecting the power-up condition or ESD event in advance and preemptively blocking the programming path, the circuit prevents false programming before it can occur, ensuring reliability while maintaining programming capability when conditions are normal.
2Reliability
If control circuitry is kept powered during ESD events to maintain defined states, then false programming is prevented, but power consumption increases and ESD damage risk increases
Solution Approach 1:
The invention extracts and isolates the control circuitry from the high-voltage programming supply during ESD events and power-up conditions. By using separate power domains and isolation circuits, the control logic can be powered down or protected during these events, preventing false programming while avoiding unnecessary power consumption and ESD damage to the control circuits.
3Productivity
If programming supply voltage is increased to ensure reliable programming, then programming effectiveness improves, but susceptibility to ESD events and false programming increases
Solution Approach 1:
The invention introduces intermediate protection circuits including voltage clamping devices, isolation transistors, and detection logic that act as mediators between the high-voltage programming supply and the eFuse array. These intermediary elements enable reliable high-voltage programming when needed while blocking or clamping harmful voltage transients during ESD events, thus decoupling programming effectiveness from ESD susceptibility.
Data Source
AI summary
An eFuse (electronic fuse) circuit has a first detector for determining whether an ESD (electrostatic discharge) event occurs at a circuit pad of an integrated circuit and provides an ESD trigger signal in response thereto. A second detector detects a presence of a first power supply voltage and provides a power on signal indicating the presence of the first power supply voltage. A fuse is permitted to be programmable when no detection of the ESD event occurs and at the same time a presence of the power on signal is detected. The fuse is not permitted to be programmed when an ESD event is detected or when there is an absence of the power on signal. An array of fuses is thereby protected from inadvertent programming from an ESD event or powering up an integrated circuit.