Spectrum M2p.59 Series, Hardware Manual, Page: 181 / 190

Details on M2p cards I/O lines
(c) Spectrum Instrumentation GmbH 181
Additional I/O Lines (Option -DigSMB)
The additional Multi Purpose I/O con -
nectors of the M2p card’s -DigSMB op -
tion from Spectrum does provide sixteen
additional Multi-Purpose I/O lines
(X4
to X19)
, which are protected against
input over voltage conditions:
For this purpose clamping diodes of the
types BAS516 are used in conjunction
with a series resistor. All I/O lines are in -
ternally clamped to signal ground and to
3.3V clamping voltage. So when con -
necting sources with a higher level than
the clamping voltage plus the forward
voltage of typically 0.6..0.7 V will be
the resulting maximum high-level level.
The maximum forward current limit for the used BAS516 diodes is 100 mA, which is effectively limited by the used series resistor for logic
levels up to 5.0V. To avoid floating levels with unconnected inputs, a pull up resistor of 10 kOhm to 3.3V is used on each line.
Additional I/O Lines (Option -DigBNC)
The additional Multi Purpose I/O con -
nectors of the digitizerNETBOX’s or
generatorNETBOX’s -DigBNC option
from Spectrum does provide eight addi -
tional Multi-Purpose I/O lines
(X4 to
X11)
, which are protected against in -
put over voltage conditions:
For this purpose clamping diodes of the
types BAS516 are used in conjunction
with a series resistor. All I/O lines are in -
ternally clamped to signal ground and to
3.3V clamping voltage. So when con -
necting sources with a higher level than
the clamping voltage plus the forward
voltage of typically 0.6..0.7 V will be
the resulting maximum high-level level.
The maximum forward current limit for the used BAS516 diodes is 100 mA, which is effectively limited by the used series resistor for logic
levels up to 5.0V. To avoid floating levels with unconnected inputs, a pull up resistor of 10 kOhm to 3.3V is used on each line.
Interfacing M2p clock in/out with M4i/M4x
M2p output to M4i/M4x input
The clock output of the M2p card is a
3.3V LVTTL signal with a 50 Ohm series
output impedance, capable of driving
50 Ohm terminated loads.
This allows to directly connect the M2p
X0 output with the AC-coupled and
50 Ohm terminated LVPECL clock input
of an M4i or M4x card.
The resulting voltage divider of the se -
ries resistor and the back termination re -
duce the 3.3V Vpp LVTTL output voltage
to half and hence limit the maximum
input swing to meet the M4i/M4x clock
input specification.
M2p input to M4i/M4x output
The clock output of the M4i/M4x cards
is AC-coupled, single-ended LVPECL
type with an output swing of approxi -
mately 800 mVpp.
Image 88: electrical connection of additional I/O lines on connection DigSMB
Image 89: electrical connection of additional I/O lines on connection DigBNC (digitizerNETBOX)
Image 90: Electrical interfacing of clock connections between M2p and M4i cards