Logic Analyzer Probes & Connectors Tutorial
- in view of the number of connections that need to be made between the circuit or system under test and the logic analyser, probes and connectors are a key issue.
With logic analysers being able to monitor a vast number of points, one of the key issues is connecting to the various points needed.
Both probes and special connectors are used for logic analyser systems to enable good reliable connections to be made in the easiest fashion.
Logic analyzer probes
With the large number of signals required to be monitored, often from a small area on a board and possibly even from one integrated circuit, the design of the probes can be a critical issue.
The logic analyzer probes contain an internal comparator where the voltage of the waveform on the board is compared against the threshold voltage. This can be set using the main instrument to a variety of levels so that signals from a variety of logic families can be monitored.
Logic analyzer probes can take a variety of physical forms, but generally fall into one of three categories:
- Multichannel probes that use a dedicated connector on the circuit board. These probes enable a large number of points to be accessed using a high density connector. This facility has to be designed on to the board and may only be retained for the development phase where access for a logic analyzer is required.
- High density compression probes. These probes use a compression contact that does not have a dedicated connector. Contacts on the board are required for this type of connection.
- Flying lead probes. As the name implies, these probes are on a flying lead that is connected to a small electronic unit that contains the electronics for detecting the high and low levels. However these flying lead probes are used to monitor points that may not be included on any of the other access points.
By Ian Poole
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