ad394td/883b Analog Devices, Inc., ad394td/883b Datasheet - Page 11

• Manufacturer Part Number: ad394td/883b
• Description: Dac 4-ch 12-bit 28-pin Cdip
• Manufacturer: Analog Devices, Inc.

OR’ed with LED indicators as shown. The test limits for each
comparator are programmed by the AD394 V
outputs. When the output of the device under testing is within
the limits, both comparators are off and D1 lights. If the output
is above or below the limits, either D4 or D5 lights.
AD394 as a Multiplier and Attenuator
So far, it has been assumed that the reference voltage V
fixed. In fact, V
−11 V < V
whatever the user prefers. This leads to the name “multiplying
D/A converters” because the output voltage, V
tional to the product of the digital input word and the voltage at
the V
D is the fractional binary value of the digital word applied to the
converter. The AD394 multiplies the digital input value by the
analog input voltage at V
22 V p-p. This in itself is a powerful tool. Applications requiring
precision multiplication with minimal zero offset and very low
distortion should consider the AD394 as a candidate. One pop-
ular use for the AD394 is as an audio frequency attenuator. The
audio signal is applied to the V
V
REFIN
OUT
terminal.
REFIN
=
−
< +11 V. It can be negative, positive, sinusoidal, or
1
REFIN
(
V
REFIN
can be any voltage within the range of
)
REFIN
(
4096
D
for any value of V
REFIN
)
input and the attenuation
(
0
<
D
<
OUT2
4095
OUT
REFIN
, is propor-
and V
)
up to
REFIN
OUT3
is
Rev. A | Page 11 of 12
code is applied to the DAC; the output voltage is the product of
the two—an attenuated version of the input. The maximum
attenuation range obtainable utilizing 12 bits is 4096:1 or 72 dB.
Figure 16. AD394 as a Multiplier or Attenuator
AD394