Upcoming Trade Shows CHINA HI-TECH FAIR 2008 Location: Shenzhen Convention and Exhibition Center Date: 12-17 October 2008 Booth Number: 2C52 Contact : Mr. Gordon Chen
Switching Power Supply: Junction-Path Shorts(1 of 4)
Problem
Small signal semiconductors and integrated circuits fail due to paths between power sources or power sources and ground that have insufficient resistance or inductance, or rely on back-biased semiconductor junctions to limit current.
Relevance
This problem occurs most frequently in environments of high ionizing radiation, high electromagnetic fields (circuit in beam of radar transmitter, etc.), and unusual transient environments such as lightning, energizing circuits through relays with contact bounce, or turning a system on and off in a time span less than the normal settling time of the circuit. Large capacitors should be treated the same as power sources.
Ionizing Radiation. During high levels of ionizing radiation, all semiconductor junctions are effectively shorted. If there are only semiconductor junctions between voltage sources, with no resistance or inductance to limit the current, sufficient current can flow to damage circuit components.
Some circuit environments produce the same results.
Transmitters. High fields of radiation (transmitters, radar beams, etc.) can induce energy into a circuit that is rectified by nonlinear circuit elements and then forward-bias normally-off junctions.
Energizing Circuits. Turning a circuit on and off rapidly can forward bias a normally back biased junction and allow current to flow.
Relay Bounce. Can have the same effect of rapidly turning a circuit on and off.
Lightning. Lighting and Electromagnetic Pulses transients can also cause the problem.
Do not use this information for design without independent verification of the information.
