Output Pin Short Detection With Sustaining Driver Latch
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Solution Overview
Problem
Integrated circuit (IC) packages face challenges in detecting shorts at output pins, especially when receiving varying voltages, leading to complex and costly detection processes, and existing solutions can cause repetitive enabling and disabling cycles that may damage the circuit and fail to meet certification standards like UL60950.
Innovation Solution
A circuit design incorporating a first driver, a second driver, a comparator, and a sustaining driver, where the comparator compares voltages at two nodes to generate a control signal, and the sustaining driver provides a threshold current to maintain the nodes at a defined operating level when a short is detected, preventing repetitive cycles and ensuring compliance with certification standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective action is taken to overcome short at the IC pin, then the circuit is protected from damage, but the protective action prevents any further detection of short at the IC pin
Solution Approach 1:
The comparator continuously monitors the voltage difference between nodes before protective action is triggered. Once a short is detected, the comparator output is latched to maintain the detection state even after protective action disables the drivers, enabling sustained detection throughout the protection period
Solution Approach 2:
The sustaining driver provides feedback current to the comparator nodes to maintain the voltage difference that enables continued detection. This feedback mechanism ensures the comparator remains in its detection state, providing continuous monitoring of the short condition even after the initial protective action
2Object-affected harmful factors
If drivers are disabled to protect the circuit from short damage, then circuit safety is improved, but repetitive enabling and disabling cycles may damage the circuit
Solution Approach 1:
The latched comparator output provides feedback to the sustaining driver, creating a self-sustaining detection state that prevents oscillation between enabled and disabled states. This feedback mechanism ensures drivers remain disabled once protective action is taken, eliminating harmful repetitive cycles
Solution Approach 2:
The latching mechanism acts as a cushion against repetitive cycling by maintaining the protective state indefinitely once triggered. This prevents the circuit from inadvertently re-enabling drivers during the protection period, cushioning against potential damage from detection failures during protection
3Device complexity
If a simple detection scheme is used for static voltage, then detection simplicity is improved, but the scheme fails for varying voltage detection
Solution Approach 1:
The differential comparator configuration provides universal detection capability for both static and varying voltages. By comparing the voltage difference between two nodes rather than monitoring absolute voltage levels, the same circuit topology effectively detects shorts regardless of whether the output voltage is static or varying
Solution Approach 2:
The second node acts as an intermediary reference that mirrors the output voltage variations. This intermediary node allows the comparator to detect shorts by measuring the voltage difference between the output node and the reference node, enabling detection of varying voltages without requiring complex absolute voltage monitoring
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents repetitive enabling and disabling cycles, protecting the circuit from damage and ensuring compliance with certification standards by maintaining the control signal at logic high until the short is rectified, thus addressing the concerns of short detection and certification requirements.
Implementation Method 1
A comparator is coupled to the first node and the second node
Implementation Method 2
A sustaining driver is coupled to the comparator and provides a threshold current to each of the first node and the second node when a short is detected at the output pin
Data Source
AI summary
In described examples, a circuit includes a first driver. The first driver is coupled to a first node, and the first node is coupled to an output pin. A second driver is coupled to a second node, and the second node is coupled to a first voltage terminal. A comparator is coupled to the first node and the second node. A sustaining driver is coupled to the comparator and provides a threshold current to each of the first node and the second node when a short is detected at the output pin.