Pin-Limited IC Test Mode via Power Supply Pattern Recognition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pin-limited IC devices, such as three-pin temperature sensing devices, face challenges in entering a test mode without disrupting normal operation and without the need for additional pins, as conventional testing methods are time-consuming and expensive, and accessing internal nodes is difficult.
Innovation Solution
A test mode control circuit that detects a predetermined signal pattern on the power supply pins, allowing the device to switch from normal to test mode without affecting normal operation, using a pattern recognition circuit and a latch to ensure accurate entry into test mode and reset to normal mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional testing methods using temperature-controlled apparatus are used, then testing can be performed, but the process becomes time-consuming and expensive
Solution Approach 1:
The patent creates an electrical copy of temperature effects by applying voltage signals to internal nodes that mimic temperature-induced voltage changes. Instead of physically heating the device, the invention injects test voltages that replicate the sensor output at different temperatures, allowing rapid electrical testing without thermal chambers.
Solution Approach 2:
The patent replaces the mechanical/thermal testing system (temperature-controlled apparatus) with an electrical signaling system. By using voltage pulses injected through power supply pins to directly stimulate internal nodes, the invention eliminates the need for physical temperature cycling equipment.
2Ease of operation
If additional pins are added to access internal nodes for testing, then testing becomes easier, but the device becomes pin-limited and package complexity increases
Solution Approach 1:
The patent makes the power supply pins serve dual functions: normal power delivery during operation and test signal injection during testing. The same pins that supply VDD and GND also carry test voltage patterns, eliminating the need for dedicated test pins and reducing package complexity.
Solution Approach 2:
The device uses its own power supply infrastructure to facilitate testing. The existing power supply pins and internal power distribution network are repurposed to deliver test signals, allowing the device to test itself without external test equipment connected to additional pins.
3Ease of operation
If the device enters test mode during normal operation, then internal nodes can be accessed, but normal operation is disrupted
Solution Approach 1:
The patent implements a feedback mechanism where the test mode control circuit continuously monitors the power supply pins for specific test signal patterns. When the characteristic pattern is detected, the circuit transitions to test mode; otherwise, normal operation continues uninterrupted. This feedback loop ensures mode switching occurs only when intended.
Solution Approach 2:
The device prepares for potential test mode entry by continuously monitoring power supply pins for test patterns. The switch control circuit is pre-configured to detect specific voltage patterns and automatically transition modes, preventing accidental disruption while readying the system for intentional testing.
4Productivity
If a signal pattern is used to enter test mode through power supply pins, then testing becomes efficient, but accidental entry into test mode may occur
Solution Approach 1:
The patent uses periodic pulse patterns with specific frequencies and duty cycles as test signals. The test mode control circuit is designed to recognize these characteristic periodic patterns, distinguishing them from normal power supply variations. The repetitive nature of the pattern provides unambiguous identification of test intent.
Solution Approach 2:
The invention changes the 'electrical color' or characteristics of the power supply signal to indicate test mode. By using distinct voltage level patterns, pulse frequencies, or signal shapes that differ fundamentally from normal operating power signals, the system creates an easily distinguishable test mode trigger that cannot be confused with regular operation.
Data Source
AI summary
A pin-limited device includes a pattern-recognition circuit that detects a predetermined signal pattern transmitted on a supply pin of the device. The predetermined signal pattern is generated within the acceptable operating voltage range of the IC device (e.g., between the minimum and maximum acceptable system voltage levels utilized to control the internal circuitry of the device). Accordingly, the pin-limited IC device continues to operate within specifications while the predetermined signal pattern is transmitted on the selected power supply pin or pins. A test mode circuit generates a switch control signal in response to the predetermined signal pattern to connect an output pin of the device, for example, to an internal node of the device. The pattern recognition circuit sets a latch when the predetermined signal pattern is detected, and the latch is reset when the device is powered down then powered up.