GENERAL DESCRIPTION
The SSM2402/SSM2412 are dual analog switches designed specifically
for high performance audio applications. Distortion and
noise are negligible over the full audio operating range of 20 Hz to
20 kHz at signal levels of up to 10 V rms. The SSM2402/
SSM2412 offer a monolithic integrated alternative to expensive
and noisy relays or complex discrete JFET circuits. Unlike conventional
general-purpose CMOS switches, the SSM2402/SSM2412
provide superb fidelity without audio clicks during switching.
Conventional TTL or CMOS logic can be used to control the
switch state. No external pull-up resistors are needed. A T
configuration provides superb OFF-isolation and true bilateral
operation. The analog inputs and outputs are protected against
overload and overvoltage.
An important feature is the guaranteed break-before-make
for all units, even IC-to-IC. In large systems with multiple
switching channels, all separate switching units must open before
any switch goes into the ON-state. With the SSM2402/
SSM2412, you can be certain that multiple circuits will all
break-before-make.
The SSM2402/SSM2412 represent a significant step forward in
audio switching technology. Distortion and switching noise are
significantly reduced in the new SSM2402/SSM2412 bipolar-
JFET switches relative to CMOS switching technology. Based
on a new circuit topology that optimizes audio performance,
the SSM2402/SSM2412 make use of a proprietary bipolar-
JFET process with thin-film resistor network capability. Nitride
capacitors, which are very area efficient, are used for the proprietary
ramp generator that controls the switch resistance transition.
Very wide bandwidth amplifiers control the gate-to-source
voltage over the full audio operating range for each switch. The
ON-resistance remains constant with changes in signal amplitude
and frequency, thus distortion is very low, less than 0.01% max.
The SSM2402 is the first analog switch truly optimized for
high-performance audio applications. For broadcasting and
other switching applications which require a faster switching
time, we recommend the SSM2412a dual analog switch with
one-third of the switching time of the SSM2402.
Brazil, RS Veranopolis
