SSM2018T Datasheet, PDF (16/16 Pages) Analog Devices – Trimless Voltage Controlled Amplifiers

SSM2018T/SSM2118T
Voltage Controlled Panner
An interesting circuit that is built with the OVCE building block
is a voltage controlled panner. Figure 48 shows the feedback
connection for the circuit. Notice that the average of both out-
puts is fed back to the input. Thus, the average must be equal
to the input voltage. When the control voltage is set for gain at
V_G, this causes V_1-G to attenuate (to keep the average the same).
On the other hand, when V_G is attenuated, V_1-G is amplified.
The result is that the control voltage causes the input to “pan”
from one output to the other. The following expressions show
how this circuit works mathematically:
V_G = 2 K ×V _IN and V _{I –G} = 2 (1 – K ) ×V _IN
where K varies between 0 and 1 as the control voltage is
changed from full attenuation to full gain respectively. When
V_C = 0, then K = 0.5 and V_G = V_1-G = V_IN. Again, trimming is
required for best performance. Pin 9 should be grounded. This
is possible because the feedback is constant and the adaptive
network is not needed. The VCP is the only application shown
in this data sheet where Pin 9 is grounded.
V_C
V_G
V_IN
18kΩ
18kΩ
V_1–G
Figure 48. Basic VCP Connection
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
16-Pin Plastic DIP (N-16) Package
16
PIN 1
1
9
0.280 (7.11)
0.240 (6.10)
8
0.210
(5.33)
MAX
0.160 (4.06)
0.115 (2.93)
0.840 (21.33)
0.745 (18.93)
0.060 (1.52)
0.015 (0.38)
0.130
(3.30)
MIN
0.022 (0.558) 0.100 (2.54)
0.014 (0.356)
BSC
0.070 (1.77)
0.045 (1.15)
SEATING
PLANE
0.325 (8.25)
0.300 (7.62)
0.195 (4.95)
0.115 (2.93)
0.015 (0.381)
0.008 (0.204)
16-Pin SOIC (R-16) Package
16
PIN 1
1
9
0.2992 (7.60)
0.2914 (7.40)
0.4193 (10.65)
0.3937 (10.00)
8
0.4133 (10.50)
0.3977 (10.00)
0.1043 (2.65)
0.0926 (2.35)
0.0291 (0.74)
0.0098 (0.25)
x 45°
0.0118 (0.30) _{0.0500 (1.27) 0.0192 (0.49)}
0.0040 (0.10)
BSC
0.0138 (0.35)
8°
0.0125 (0.32) ^0°
0.0091 (0.23)
0.0500 (1.27)
0.0157 (0.40)
–16–
REV. A