Tektronix TLA7AA Series, Service Manual

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Theory of Operation
3- 2
TLA7AXX/TLA7NAX Logic Analyzer Module Service Manual
The processor system includes the instrument firmware. To facilitate upgrades,
the firmware resides in Flash ROM. The processor system also includes the
nonvolatile RAM (NVRAM) used for the calibration constants, module serial
numbers, and PowerFlex configuration information.
The Communications Interface transfers commands and data between the
mainframe and the mainframe controller. Signals pass between the logic analyzer
module and the mainframe through the rear connectors.
The onboard power supplies r5 V, --5.2 V,
±
12 V, and
±
24 V from the
mainframe through the rear connectors. Voltage converters produce the +2.5 V
supply for use on the acquisition board through the 160-pin connector between
the LPU and acquisition board.
Acquisition Board
The acquisition board accepts input signals from the probes and converts them to
digital information. A 160-pin connector provides interconnections with the LPU
board.
The system clock is derived from the 10 MHz clock from the backplane through
a phase-locked loop. The acquisition run circuitry is integrated with the clock
circuitry to support time correlation.
The probe interface consists of ASICs that receive data from the probes, compare
the data against a threshold, and transfer the digital information to CMOS ASICs
via differential outputs. Each ASIC in the probe interface receives 16 data
channels and one clock channel. In addition to providing digital signals to the
CMOS ASICs, the probe interface ASICs contain outputs for the Analog output
signals.
The acquisition board for the TLA7Axx logic analyzer modules has four SMA
connectors that connect to the four BNC connectors on the front panel. The
software (via the user interface) determines which signals will be sent to the four
Analog output connectors. Regardless of the number of channels in the module,
there will always be four signals available to route to the Analog output
connectors.
Voltage converters produce the +3.3 V supply on the acquisition board and the
±
3 V supplies for the active probes.
Communications Interface
Power Supplies
Clock Circuitry
Probe Interface
Analog Output Interface
Power Supplies