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Publication No. 980938 Rev. K
Model T940 User Manual
Astronics Test Systems
DR1 Driver/Receiver Board B-5
Signal Descriptions
I/O CONTROL
Signals used to control isolation, termination, NV data and
load relays
MP SIG
Multi-Purpose signal from the data sequencer.
CBUS
An internal Control Bus connecting the digital board to the
Driver/Receiver board.
MF SIG
Multi-Function signal output to the PWR connector.
Firmware & NV Data
The Control Logic firmware is loaded via a serial PROM on power up or VXI
Reset. The firmware is field-upgradeable using our supplied loader utility.
Nonvolatile data (serial number, assembly revision is stored in an on-board
EEPROM.
Signal Descriptions
I/O CONTROL
Signals used to program firmware and NV DATA.
DR1 Characteristics
Table B-1: DR1 Characteristics
Description
Characteristics
Digital I/O Type
LVTTL (74LVC2G125)
Channels
32 single-ended (SE) per I/O board
Per channel relay isolation
Output Voltage
V
OL
: 0.55 V (max)
V
OH
: 2.4 V (min)
Output Drive Current (typical)
Source/Sink: 24 mA
Output Impedance
(Program selectable per pin)
Direct or 100
Ω Series (-001)
Direct or 50
Ω Series (-002)
Input Voltage
V
IL
: 0.8 V (max)
V
IH
: 2.0 V (min)
Input Impedance
(Program selectable per pin)
100 Ω pull-up to VCC (+3.3 V)
100 Ω pull-down to ground
(Ch1-32, Aux1-4 only)
Skew (Channel-to-Channel)
< 3 ns (drive and compare)
Auxiliary I/O Channels
(per I/O board)
LVTTL (Aux 1-4) Like the channels with
optional pull-up and pull-down
LVTTL (Aux 5-8)
ECL (Aux 9-12) Single-ended or Differential
AUX I/O is bi-directional
Per channel relay isolation
Data Rate (max)
50 MHz (input and output)