Tektronix Keithley AOM4 Programmable Excitation Module Rev. C User manual
AOM4
Programmable Excitation Module
The AOM4 Programmable Excitation Module provides four channels of high-speed
anaIog voltage output. Each channel has an independent D/A converter.
The D/A converters offer true X&bit resolution with a maximum nonlinearity of *.0X!%.
A single 0-10.2375V output range has a resolution of 2.5mV and a maximum output current of 4OmA.
Each output stage can be supplied either by the internal +l5V supply, or by an external
supply of +l5 (+2, -0) VDC.
A system strobe feature, supported by two levels of data latching in the D/A converters,
allows any number of D/A channels to be updated simultaneously.
Signals are connected directly to the module via screw terminals mounted on the righthand side of the module board.
The AOM4 module may be placed in any available slot in the system. To install the
module, first turn off power and remove the top cover of the mainframe. Insert the
module in the desired slot with the component side facing the power supply. Generally, analog modules should be placed in the low-numbered slots to isolate them from
power supply thermal and noise effects.
CAUTION: Always turn off the system power before installing or removing modules.
To avoid possible EM1 radiation never operate the system with the top cover removed.
User-Configured Components
All output connections are made to screw terminals located on the module. Two terminals are provided for each channel: signal output and common ground.
Table 1. User-Configured Components on the AOM4
Name
Screw Terminals Jl7’l Output Connection Channels O-3
Jumper 101
Designation Function
Part of Jl.7l External Power Connections
WlOl Select Internal/External Supply
Document Number: 500-932-01 Rev. C
AOM4-1
AOM42
Figure 1. AOM4 Module
Connections
Terminal connections are shown in Figure 2, which illustrates a typical connecting
scheme. The use of shielded cable is recommended to minimize the possibility of EM1
radiation. Connect one end of the shield to AOM4 ground and leave the other end
disconnected.
IL!8
J---J-+
I“,” I
EXTERNAL SUPPLY,
(SEE TEXT FOR MAXIMUM
VALUE)
Figure 2. Typical AOM4 Output Connections (Channel 0 shown)
Voltage Supply Connections
The channel outputs may be operated from either the internal +l5V supply or an exter-
nal supply of +l5 (+2,
be in the INT position. To operate the module on an external supply, place WlOl in the
EXT position and connect the supply to the external supply terminals. Be sure to
observe proper polarity.
-0) VDC. When using the internal supply, jumper WlOl must
Output Loading Considerations
Each channel on the AOM4 card can supply a maximum of lO.2375V at 40mA. Thus
there is a minimum resistance value that can be conconnected across the outputs
without loading them down. With the above voltage and current values, the minimum
recommended load resistance is 25612. Note that the outputs are short circuit protected,
so that lower resistance values will not damage the module, but they will affect output
accuracy. However, the maximum recommended load capacitance is O.&S. Exceeding
this value may cause the output channel to oscillate.
Commands
AOM4 module commands are listed in Table 2. Table 3 summarizes the locations for
slot-dependent commands.
AOM4-3
Table 2. Commands Used with the AOM4 Module
Command
D/A CONTROL
D/A DAL4
STROBE
Table 3. Locations of Slot-dependent Commands
Slot CMDA CMDB
Slot 1
Slot 2
Slot 3
Slot 4
Slot 5
Slot 6
Slot 7
Slot 8
Slot 9
Slot lo
D/A CONTROL
CFFSO
CFF82
cFF84
CFF86
CEE88
cFF8A
CFF8C
CFF8E
CFF90
CFF92
Location
Slot-dependent CMDA
Slot-dependent CMDB
CFF9D
Location: Slot-dependent CMDA
D/A CONTROL always precedes D/A DATA, indicating to the AOM4 module which
channe1 of analog output to update, and which byte of data to load. Table 4 lists values
written to the D/A CONTROL locations.
The high and low bytes of data may be updated independently and in any order; there
is no hardware reason that both bytes must be updated at the same time. Similarly,
channels can be updated independently and in any order.
The location assigned to D/A CONTROL varies depending on which baseboard slot
holds the D/A converter being addressed (See Table 3).
Table 4. Values Written to D/A CONTROL
Function Binary Hex
Channel 0 low byte 0000
Channel 0 high byte 0001
Channel 1 low byte 0010
Channel 1 high byte 0011
Channel 2 low byte 0100
Channel 2 high byte 0101
ChanneI 3 low byte 0110
Channel 3 high byte 0111
HO 0
Hl 1
H2 2
H3 3
H4 4
H5 5
iz; 7 6
Decimal
AOM4-4