Tektronix TLA7AA Series, Service Manual

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TLA7AXX/TLA7NAX Logic Analyzer Module Service Manual
3- 1
Theory of Operation
This chapter describes the general operation of the logic analyzer module. This
information is intended to help you isolate faults to the circuit board or probe
level. It supplements diagnostic and troubleshooting information presented in the
Troubleshooting section beginning on page 6--27.
The following Block Level Description describes circuit operation to the
functional block level. Block diagrams are located in the Diagrams chapter
beginning on page 9--1.
Block Level Description
The block level description provides an overview of each functional circuit
within the logic analyzer module. Except for the number of channels, the basic
operation is the same for each individual module and for merged modules.
The basic logic analyzer module consists of two main circuit boards: the Local
Processing Unit (LPU) board and the Acquisition board. Each circuit board has
two connectors on the rear of the boards that provide connections to the
mainframe.
Up to four active probes per module acquire data from the target system and send
it to the logic analyzer module for processing. The logic analyzer module can use
different types of probes (such as general purpose, high-density, or differential)
depending on the user’s application.
A single 102-channel or a 136-channel logic analyzer module can be merged
with up to five modules to create a two-, three-, four-, or five-module-wide logic
analyzer. The 34-channel and 68-channel modules do not support merging.
Local Processor Unit (LPU) Board
The LPU board controls instrument hardware, signal acquisition, power
conditioning, and communications functions. A 160-pin connector provides
interconnections with the acquisition board for power supplies, data and control
signals.
The processor system contains a microprocessor that controls the entire
instrument. Commands and data sent to the instrument through the mainframe
pass through the communications interface, which resides on the bus. The bus
also routes data between the main processor system and the acquisition board.
Processor System