SSM2412_15 Datasheet, PDF (11/12 Pages) Analog Devices – Dual Audio Analog Switches

SSM2402/SSM2412
OLETE _{Figure 8. Switcher Functional Block Diagram}
The routing switcher bus carries high level unbalanced audio,
S but is driven with low impedance sources. With the output im-
pedance of the SSM2015 at virtually 0 Ω and the SSM2402
switch ON, resistance is typically 60 Ω. Bus-to-bus crosstalk is
exceptionally low. For example, assuming 14 pF coupling be-
B ^{tween buses and 20 kHz signal, the crosstalk (isolation) exceeds}
80 dB. The 14 pF would be representative for the 16 × 1 stereo
design shown. Shielding of the buses with a printed circuit
board ground plane and physically isolating the input and out-
O ^{put circuits will reduce the crosstalk even further. The “T” con-}
Overall performance of the 16 × 1 stereo switcher is noteworthy.
Input-to-output frequency response is flat to within 1 dB over a
10 Hz to 50 kHz band. Total harmonic distortion plus noise is
less than 0.03%, from 20 Hz to 20 kHz. SMPTE intermodula-
tion distortion is less than 0.02%. The use of ± 18 V dc power
supplies produces a +30 dBm clip level, even when driving
600 Ω loads.
Table I. Circuit Performance Specifications
Max Input Level
+30 dBu
figuration of the SSM2402 switch virtually eliminates crosstalk Input Impedance, Unbalanced
100 kΩ
between the various input signal sources.
Input Impedance, Balanced
200 kΩ
The output amplifier incorporates a buffer amplifier that pro-
vides 4 dB of gain (nominally), with adjustable output level trim
control. The buffer also isolates the switching bus from the bal-
anced output amplifier circuit. The balanced output is designed
to drive 600 Ω loads and utilizes two SSM2134 IC amplifiers.
The differential design increases drive capability, yet increases
the heat dissipation surface area, and keeps IC package tem-
perature well within safe operating limits, even when driving
600 Ω loads. The SSM2134 is recommended due to its low
noise, wide frequency response, and output drive current
capabilities.
Common-Mode Rejection (20 Hz to 20 kHz)
Common-Mode Voltage Limit
Max Output Level
Output Impedance
Gain Control Range
Output Voltage Slew Rate
Frequency Response (± 0.05 dB)
Frequency Response (± 0.5 dB)
THD + Noise (20 Hz to 20 kHz, +8 dBu)
THD + Noise (20 Hz to 20 kHz, +24 dBu)
IMD (SMPTE 60 Hz & 4 kHz, 4:1, +24 dBu)
Crosstalk (20 Hz to 20 kHz)
>70 dB
± 98 V Peak
+30 dBu/dBm
67 Ω
± 2 dB
6 V/µs
20 Hz to 20 kHz
10 Hz to 50 kHz
0.005%
0.03%
0.02%
>80 dB
S/N Ratio @ 0 dB Gain
135 dB
REV. A
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