Analog Devices SSM2166 Automobile User Manual


 
SSM2166
REV. A
–11–
Figure 23c. Evaluation Board Backside Metallization
(Not to Scale)
Signal sources are connected to the SSM2166 through a 1/8"
phone jack where a 0.1 µF capacitor couples the input signal to
the SSM2166’s +IN pin (Pin 7). As shown in Figure 22 and in
microphone applications, the phone jack shield can be optionally
connected to the board’s ground plane (Jumper J1 inserted into
board socket pins labeled “1” and “2”) or to the SSM2166’s
VCA
R
input at Pin 4 (Jumper J1 inserted into board socket pins
labeled “1” and “3”). If the signal source is a waveform or
function generator, the phone jack shield is to be connected
to ground.
For ease in making adjustments for all of the SSM2166’s con-
figuration parameters, single-turn potentiometers are used
throughout. Optional Jumper J2 connects the COMP RATIO
pin to ground and sets the SSM2166 for no compression (that
is, compression ratio = 1:1). Optional Jumper J3 connects the
SSM2166’s POWER DOWN input to ground for normal opera-
tion. Jumper J3 can be replaced by an open-drain logic buffer
for a digitally-controlled shutdown function. An output signal
MUTE function can be implemented on the SSM2166 by con-
necting the GAIN ADJUST pin (Pin 2) through a 330 resis-
tance to ground. This is provided on the evaluation board via
R11 and S1. A capacitor C5, connected between Pin 2 and
ground and provided on the evaluation board, can be used to
avoid audible “clicks” when using the MUTE function.
To configure the SSM2166’s input buffer for gain, provisions for
R1, R2, and C2 have been included. To configure the input
buffer for unity-gain operation, R1 and R2 are removed, and a
direct connection is made between the –IN pin (Pin 6) and the
BUF
OUT
pin (Pin 5) of the SSM2166.
The output stage of the SSM2166 is capable of driving > 1 V
rms (3 V p-p) into > 5 k loads, and is externally available
through an RCA phono jack provided on the board. If the out-
put of the SSM2166 is required to drive a lower load resistance
Figure 23a. Evaluation Board Topside Silkscreen
(Not to Scale)
Figure 23b. Evaluation Board Topside Metallization
(Not to Scale)