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General-Purpose Probing System Description
The standard probing system provided with the logic analyzer consists of a
probe tip assembly, probe cable, and grabbers. Because of the passive design
of the probes, there are no active circuits at the outer end of the cable. The
rest of this chapter is dedicated to general-purpose probing.
The passive probing system is similar to the probing system used with
high-frequency oscilloscopes. It consists of a series RC network
(90 k
Ω
in parallel with 8 pF) at the probe tip, and a shielded, resistive
transmission line. The advantages of this system include the following:
•
250
Ω
in series with 8-pF input capacitance at the probe tip for minimal
loading.
•
Signal ground at the probe tip for high-speed timing signals.
•
Inexpensive, removable probe tip assemblies.
Probe Tip Assemblies
Probe tip assemblies allow you to connect the logic analyzer directly to the
target system. This general-purpose probing is useful for discrete digital
circuits. Each probe tip assembly contains 16 probe leads (data channels),
1 clock lead, a pod ground lead, and a ground tap for each of the 16 probe
leads.
Probe Tip Assembly
Probing
General-Purpose Probing System Description
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