| 摘要 |
A first sensor for the detection of dielectric failure (by burning) within a multilayer printed circuit assembly comprises an isolated conductive layer. This first sensor is connected by a first diode to a single wire which also connects a second, temperature, sensor via a second diode (system ground is a return). A multiplicity, nominally 16, of such single wire connected sensor pairs are selectable in accordance with an externally (microprocessor) furnished address. During a first time period, an externally (microprocessor) selected interrogation of temperature causes a first, positive, voltage bias to be applied to the selected sensor pair resulting in a current linear with temperature (over the range of 0 DEG C. to 100 DEG C.) in the second sensor. This current is transformed to voltage, offset by 273 DEG Kelvin, amplified, and converted to a digital value for issuance to an external (microprocessor) requestor. During a second time period, an externally (microprocessor) selected interrogation of dielectric failure causes a second, negative, voltage bias to be applied to the selected sensor pair. Any current sensed-which represents failure shorts between the isolated conductive layer and any other voltage, ground, or signal within the multilayer printed circuit assembly-is transformed to voltage, amplified, digitalized and issued externally. If neither temperature nor dielectric leakage currents can be properly sensed, and especially for plural addressable sensor pairs upon the same printed circuit assembly, then the assembly is deemed to be unconnected or improperly pluggably connected. Temperature (over temperature), dielectric failure, and failed connection are cyclically continuously monitored for a multiplicity of sensor pairs upon a plurality of printed circuit assemblies with an individual sensor test, or interrogation, time of 50 milliseconds.
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