2
LC MOS LOGDAC
Logarithmic D/A Converter
a
AD7111/AD7111A
FUNCTIO NAL BLO CK D IAGRAMS
FEATURES
Dynam ic Range: 88.5 dB
Resolution: 0.375 dB
On-Chip Data Latches
+5 V Operation
AD7111A Pin Com patible w ith AD7524
Low Pow er
V
V
DD
IN
R
I
FB
AD7111
OUT
17-BIT DAC
AGND
APPLICATIONS
Audio Attenuators
17-BIT LATCH
Sonar System s
Function Generators
Digitally Controlled AGC System
DECODE LOGIC
8-BIT BUFFER
CONTROL LOGIC
GENERAL D ESCRIP TIO N
T he LOGDAC AD7111/AD7111A are monolithic multiplying
D/A converters featuring wide dynamic range in a small pack-
age. Both DACs can attenuate an analog input signal over the
range 0 dB to 88.5 dB in 0.375 dB steps. T hey are available in
16-pin DIPs and SOIC packages. T he AD7111 is also available
in a 20-terminal LCCC package.
D0 – D7
DGND
CS
WR
V
V
DD
IN
R
FB
T he degree of attenuation across the DAC is determined by an
8-bit word applied to the onboard decode logic. T his 8-bit word
is decoded into a 17-bit word which is then applied to a 17-bit
R-2R ladder. T he very fine step resolution, which is available
over the entire dynamic range, is due to the use of this 17-bit
DAC.
AD7111A
I
OUT
17-BIT DAC
AGND
17-BIT LATCH
T he AD7111/AD7111A are easily interfaced to a standard 8-bit
MPU bus via an 8-bit data port and standard microprocessor
control lines. T he AD7111 WR input is edge triggered and re-
quires a rising edge to load new data to the DAC. T he AD7111A
WR is level triggered to allow transparent operation of the
latches, if required. It should also be noted that the AD7111A is
exactly pin and function-compatible with the AD7524, an in-
dustry standard 8-bit multiplying DAC. T his allows an easy up-
grading of existing AD7524 designs which would benefit both
from the wider dynamic range and the finer step resolution of-
fered by the AD7111A.
DECODE LOGIC
8-BIT BUFFER
CONTROL LOGIC
D0 – D7
DGND
CS
WR
P RO D UCT H IGH LIGH TS
1. Wide Dynamic Range: 0 dB to 88.5 dB attenuation range in
0.375 dB steps.
T he AD7111/AD7111A are fabricated in Linear Compatible
CMOS (LC2MOS), an advanced, mixed technology process that
combines precision bipolar circuits with low power CMOS logic.
2. Small Package: T he AD7111/AD7111A are available in
16-pin DIPs and SOIC packages.
3. T ransparent Latch Operation: By tying the CS and WR in-
puts low, the DAC latches in the AD7111A can be made
transparent.
LOGDAC is a registered trademark of Analog Devices, Inc.
4. Fast Microprocessor Interface: Data setup times of 25 ns and
write pulse width of 57 ns make the AD7111A compatible
with modern microprocessors.
REV. 0
Inform ation furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assum ed by Analog Devices for its
use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
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