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FEATURES
Zero-Chip Interface to Digital Signal Processors
Complete DACPORT®
On-Chip Voltage Reference
Voltage and Current Outputs
Serial, Twos-Complement Input
؎3 V Output
Sample Rates to 390 kSPS
94 dB Minimum Signal-to-Noise Ratio
–81 dB Maximum Total Harmonic Distortion
15-Bit Monotonicity
؎5 V to ؎12 V Operation
16-Pin Plastic and Ceramic Packages
Available in Commercial, Industrial, and Military
Temperature Ranges
APPLICATIONS
Digital Signal Processing
Noise Cancellation
Radar Jamming
Automatic Test Equipment
Precision Industrial Equipment
Waveform Generation
PRODUCT DESCRIPTION
The AD766 16-bit DSP DACPORT provides a direct, threewire interface to the serial ports of popular DSP processors, including the ADSP-2101, TMS320CXX, and DSP56001. No
additional “glue logic” is required. The AD766 is also complete, offering on-chip serial-to-parallel input format conversion, a 16-bit current-steering DAC, voltage reference, and a
voltage output op amp. The AD766 is fabricated in Analog
Devices’ BiMOS II mixed-signal process which provides bipolar
transistors, MOS transistors, and thin-film resistors for precision analog circuits in addition to CMOS devices for logic.
The design and layout of the AD766 have been optimized for ac
performance and are responsible for its guaranteed and tested
94 dB signal-to-noise ratio to 20 kHz and 79 dB SNR to
250 kHz. Laser-trimming the AD766’s silicon chromium thinfilm resistors reduces total harmonic distortion below –81 dB
(at 1 kHz), a specification also production tested. An optional
linearity trim pin allows elimination of midscale differential
linearity error for even lower THD with small signals.
The AD766’s output amplifier provides a ± 3 V signal with a
high slew rate, small glitch, and fast settling. The output amplifier is short circuit protected and can withstand indefinite shorts
to ground.
16-Bit
DSP DACPORT
AD766
FUNCTIONAL BLOCK DIAGRAM
The serial interface consists of bit clock, data, and latch enable
inputs. The twos-complement data word is clocked MSB first
on falling clock edges into the serial-to-parallel converter, consistent with the serial protocols of popular DSP processors. The
input clock can support data transfers up to 12.5 MHz. The
falling edge of latch enable updates the internal DAC input register at the sample rate with the sixteen bits most recently
clocked into the serial input register.
The AD766 operates over a ± 5 V to ± 12 V power supply range.
The digital supplies, +VL and –VL, can be separated from the
analog signal supplies, +VS and –VS, for reduced digital
crosstalk. Separate analog and digital ground pins are also provided. An internal bandgap reference provides a precision voltage source to the output amp that is stable over temperature and
time.
Power dissipation is typically 120 mW with ± 5 V supplies and
300 mW with ± 12 V. The AD766 is available in commercial
(0°C to +70°C), industrial (–40°C to +85°C), and military
(–55°C to +125°C) grades. Commercial and industrial grade
parts are available in a 16-pin plastic DIP; military parts processed to MIL-STD-883B are packaged in a 16-pin ceramic
DIP. See Analog Devices’ Military Products Databook or current
military data sheet for specifications for the military version.
DACPORT is a registered trademark of Analog Devices, Inc.
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
