Datasheet

AD8802/AD8804
REV. 0
–14–
USER
INPUTS
3
TO 2nd AD8802/4
ARRAY IF NEEDED
TO 2nd TEMP SENSOR
IF NEEDED
4
TO 3rd TEMP SENSOR
IF NEEDED
4
0.1µF
10µF
+5V
+5V
0.1µF
TMP14
0.01µF
3
V
CC
OUT
RS
DIS
THR
TRIG
GND
AD8802/4
TLC555
2.5 V
REF
SET 1
SET 2
SET 3
SET 4
HYS
TRIP 1
TRIP 2
TRIP 3
TRIP 4
V
+
GND
SLEEP
O1
O3
O4
O2
05–8
09–12
V
DD
GND
SHDN
CS
CLK
SDI
P2.0
P2.1
P2.2
P2.3
P2.4
80CL51 µC
P1.0/INT2
P0.0
P0.7
P3.2
P3.1
P3.0
P3.3
V
REFH
+5V
Figure 27. Temperature Sensor Array with Programmable Setpoints
The gain of the SSM2018T is controlled by the voltage at Pin 11.
For maximum attenuation of –100 dB a control signal of 3.0 V
typ is necessary. The control signal has a scale of –30 mV/dB
centered around 0 dB gain for 0 V of control voltage, therefore,
for a maximum gain of 40 dB a control voltage of –1.2 volts is
necessary. Now notice that the normal +5 V to GND voltage
range of the AD8802/AD8804 does not cover the 3.0 V to
–1.2 V operational gain control range of the SSM2018T. To
cover the operating gain range fully and not exceed the maxi-
mum specified power supply rating requires the O1 output of
AD8802/AD8804 to be level shifted down. In Figure 28, the
level shifting is accomplished by a Zener diode and 1/4 of an
OP420 quad op amp. For applications that require only
TMP14, and makes the necessary adjustments to the AD8802/
AD8804 before shutting down again. The 80CL51 consumes
only 50 µA when operating at 32 kHz, in which case there
would be no need for the TLC555, which consumes 1 mW typ.
12 Channel Programmable Voltage Controlled Amplifier
The SSM2018T is a trimless Voltage Controlled Amplifier
(VCA) for volume control in audio systems. The SSM2018T is
the first professional quality audio VCA in the marketplace that
does not require an external trimming potentiometer to mini-
mize distortion. The TrimDAC shown in Figure 28 is not being
used to trim distortion, but rather to control the gain of the am-
plifier. In this configuration up to twelve SSM2018T can be
digitally controlled. (Please refer to the SSM2018T data sheet
for more specifications and applications information.)
–15V
R
O
150kΩ
+V
50pF
18kΩ
18kΩ
1µF
18kΩ
1µF
+15V
8
1
2
3
4
7
6
5
14
13
12
11
16
15
10
9
SSM2018T
OP420A
1.2V
+15V
50kΩ
OPTIONAL FOR
0 TO 40dB GAIN
V
OUT
O1
V
REFH
O2–
O12
TO 8 MORE CHANNELS
O2
O3
O4–O12
CS
CLK
SDI
3
TO µC
1µF
V
REFL
(AD8804
ONLY)
OUT
IN
GND
REF195
V+
GND
+15V
AD8802/4
47pF
NC
Figure 28. 12-Channel Programmable Voltage Controlled Amplifier