SSM2142
THE CABLE PAIR
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
The SSM2142 is capable of driving a 10 V rms signal into
600
Ω
and will remain stable despite cable capacitances of up to
0.16
µF
in either balanced or single-ended configurations. Low
impedance shielded audio cable such as the standard Belden
8451 or similar is recommended, especially in applications
traversing considerable distances. The user is cautioned that the
so-called “audiophile” cables may incur four times the capac-
itance per unit length of the standard industrial-grade product.
In situations of extreme load and/or distance, adding a second
parallel cable allows the user to trade off half of the total line
resistance against a doubling in capacitive load.
SINGLE-ENDED OPERATION
0.210
(5.33)
MAX
0.160 (4.06)
0.115 (2.92)
8-Lead Plastic DIP
8
5
0.280 (7.11)
0.240 (6.10)
1
4
0.070 (1.77)
0.045 (1.15)
0.430 (10.92)
0.348 (8.84)
0.325 (8.25)
0.300 (7.62)
The SSM2142 is designed to be compatible with existing
balanced-pair interface systems. Just as in transformer-based
circuits, identical but opposite currents are generated by the
output pair which can be ground-referenced if desired and
transmitted on a single wire. Single-ended operation requires
that the unused side of the output pair be grounded to a solid
return path in order to avoid voltage offset errors at the nearby
input common. The signal quality obtained in these systems is
directly dependent on the quality of the ground at each end of
the wire. Also note that in single-ended operation the gain
through the device is still 6 dB, and that the SSM2142 incurs
no significant degradation in signal distortion or output drive
capability, although the noise rejection inherent in balanced-
pair systems is lost.
POWER SUPPLY SEQUENCING
0.015
(0.381) TYP
0.130
(3.30)
MIN
SEATING
PLANE
0.015 (0.381)
0.008 (0.203)
0.022 (0.558)
0.014 (0.356)
0.100
(2.54)
BSC
0 - 15
8-Lead Cerdip
0.005 (0.13) MIN
0.055 (1.35) MAX
8
5
0.310 (7.87)
0.220 (5.59)
1
4
0.070 (1.78)
0.030 (0.76)
A problem occasionally encountered in the interface system en-
vironment involves irregular application of the supplies. The
user is cautioned that applying power erratically can inadvert-
ently bias parts of the circuit into a latch-up condition. The
small geometries of an integrated circuit are easily breached and
damaged by short-risetime spikes on a supply line, which usu-
ally demonstrate considerable overshoot. The questionable
practice of exchanging components or boards while under
power can create such an undesirable sequence as well. Possible
options which offer improved board-level device protection
include: additional bypass capacitors, high-current reverse-
biased steering diodes between both supplies and ground, vari-
ous transient surge suppression devices, and safety grounding
connectors.
Likewise, power should be applied to the device before the
output is connected to “live” systems which may carry voltages
of sufficient magnitude to turn on the output devices of the
SSM2142 and damage the device. In any case, of course, the
user must always observe the absolute maximum ratings shown
in the specifications.
0.405 (10.29) MAX
0.200
(5.08)
MAX
0.060 (1.52)
0.015 (0.38)
0.320 (8.13)
0.290 (7.37)
0.200 (5.08)
0.125 (3.18)
0.150
(3.81)
MIN
0.015 (0.38)
0.008 (0.20)
0.023 (0.58)
0.014 (0.36)
0.100 (2.54)
BSC
0 - 15
SEATING PLANE
16-Lead Small Outline (SOIC)
16
0.4193 (10.65)
0.3937 (10.00)
1
9
0 -8
0.2992 (7.60)
0.2914 (7.40)
8
0.0500 (1.27)
0.0157 (0.40)
0.0291 (0.74)
0.0098 (0.25) x 45
0.4133 (10.50)
0.3977 (10.10)
0.1043 (2.65)
0.0926 (2.35)
0.0118 (0.30)
0.0040 (0.10)
SEATING
PLANE
0.0500
(1.27)
BSC
0.0192 (0.49)
0.0138 (0.35)
0.0125 (0.32)
0.0091 (0.23)
SEE
DETAIL
ABOVE
–6–
REV. B
PRINTED IN U.S.A.
C1496–15–1/91
AD [ ANALOG DEVICES ]
