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Appendix C


LW400-09A Digital Output Option

Introduction The LW400-09A Digital Output option provides 8-bit TTL and
ECL, digital outputs corresponding to the current value of the
channel 1 analog output. The latched digital data, which is held
for the duration of the sample clock, is available via two rear
panel mounted connectors. Digital data is available whenever
the channel 1 output is enabled.

LW400's, with the digital output option, include a special digital
editing mode for the creation of user specified data patterns.
Byte wide data patterns or selected bits within the 8-bit wide
digital word may be programmed. Digital data patterns created
using this editor are identified as "Digital" waveforms. Digital
waveforms can be edited using the same "cut and paste" tools
available for analog waveforms. The major difference between
the two waveform types is that digital waveforms are not
processed to remove discontinuities at transitions. This also
means that Time editing functions, such as sub-sample Move,
are not useable with digital waveforms and are limited to analog
waveforms only.

Specifications
Digital outputs: 8 bits corresponding to the channel 1 analog output plus CLOCK
and CLOCK* (TTL only).

Digital output modes: ECL, TTL all available on output connectors simultaneously.

Mating output connector: SMB for ECL output
20 pin P/N 3M-3421-7020 for TTL output.

Maximum data
output clock rate: ECL, 400 MBytes/sec; TTL 100 MBytes/sec.




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Appendix C


ECL outputs: Levels:
Parameter Min Typ Max
VOH -0.98 V -0.8 V -0.71V
VOL -1.95 V -1.8 V -1.58 V
Note: output load is 50 to -2 Volts.

Timing:
Parameter Min Typ Max
Clock to 7 ns 8 ns 9.8 ns
Analog Output
Setup Time * T-660 ps T-485 ps T-310 ps
Hold Time 310 ps 485 ps 660 ps
Data skew - 80 ps 250 ps
* T is clock period (i.e. 2.5 ns for 400 MHz clock)



TTL :
Levels:
Parameter Min Typ Max
VOH 2.00 V 2.60 V -
VOL - 0.35 V 0.80 V


Timing:
Parameter Min Typ Max
Clock to 10 ns -
Analog
Output
Setup Time * T -5.7 ns T -0.5 ns T+3.9 ns
Hold Time -3.9 ns 0.5 ns 5.7 ns
Data skew - - 1 ns
* T is clock period (i.e. 10 ns for 100 MHz clock)




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Appendix C

CONNECTOR PINOUTS

Note1: D7 signifies the bit which corresponds to analog signal most
significant bit (MSB), and D0 signifies the bit which corresponds
to the least significant bit (LSB).

Note2: TTL outputs back terminated in 75 ohms

TTL Port 1 - TCLK 2 Ground
3 - TCLK* 4 Ground
5 - D0 (LSB) 6 Ground
7 - D1 8 Ground
9 - D2 10 Ground
11 - D3 12 Ground
13 - D4 14 Ground
15 - D5 16 Ground
17 - D6 18 Ground
19 - D7 (MSB) 20 Ground


ECL Port J800 - D0 (LSB)
J700 - D1
J600 - D2
J500 D3

J400 - D4
J300 - D5
J200 - D6
J100 - D7 (MSB)

J900 - ECLOCK




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Appendix C


Interconnection Information:

TTL: The LW400-09A includes 75 back terminations on all the TTL
output lines. These resistors are used to match the transmission
line impedance taking into account the additional source
impedance of the TTL driver. The 75 resistors match the 80
impedance of the flat cable fairly well. In this fashion, no
termination resistor is required or desired. The most important
consideration in this scheme is that the load should be as close
to an open circuit as possible. One, or at most, two TTL loads
should be placed at the termination of the line. Capacitance at
the termination will have a detrimental effect on the rise time of
the received signal. Every effort should be made to limit parasitic
capacitance at the termination of the cable to under 10 pF. All
grounds should be tied together at the load side of the cable.

ECL: The LW400-09A provides 464 internal pulldown resistors at
the ECL output drivers. The ECL outputs need to be terminated
at the load side of the cable. The most optimum interconnection
would utilize ECL line receivers at the receiver end of the cable,
with termination resistors of 50 tied to -2 Volts.

Cable Selection: For TTL output: Spectra Strip 843-132 - 280-020.




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Appendix C




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Appendix C


Creating A Digital Waveform A new digital waveform, as in the case of a new analog
waveform, is created by pressing the Select Wave button on the
front panel and choosing the New menu item. Select New CH1
Wave from the New menu and then enter the waveform name
in the Waveform menu field. Press the Accept softkey to
create the new waveform.




Figure C3.1


Press the EDIT button on the front panel of the WaveStation to
display the Edit menu. The presence of the LW400-09A Digital
Output option is indicated by the Digital Edit softkey shown in
Figure C3.1 above. Select Digital Edit to display the Digital
Edit menu, shown in figure C3.2 below. Note that waveforms
created in this editor are tagged as "digital". Digital waveforms
are not subject to signal processing functions to remove
discontinuities. They are also allowed to use a wider range of
sample clock rates.




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Appendix C

Digital waveforms are created and edited by specifying the digital
value of the waveform, in hexadecimal, in the Value field. This
value is entered, starting at the location specified in the Left
Cursor field, with a length set in the Duration field whenever the
Set Value softkey is pressed. The Duration and Left Cursor
fields will read out in units of time or sample points as selected
by the user using the Format softkey switch. A user message,
"Use the m-M keys for entering A-F" appears on the display
while the Digital Edit or Bit Edit menus are displayed.

Note that the units multiplier buttons, m,