FUNCTIONAL BLOCK DIAGRAM
REV. B
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.
a
14-Bit 128 kSPS
Complete Sampling ADC
AD779*
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 Fax: 617/326-8703
FEATURES
AC and DC Characterized and Specified (K, B, T
Grades)
128k Conversions per Second
1 MHz Full Power Bandwidth
500 kHz Full Linear Bandwidth
80 dB S/N+D (K, B, T Grades)
Twos Complement Data Format (Bipolar Mode)
Straight Binary Data Format (Unipolar Mode)
10 MV Input Impedance
16-Bit Bus Interface (See AD679 for 8-Bit Interface)
Onboard Reference and Clock
10 V Unipolar or Bipolar Input Range
MIL-STD-883 Compliant Versions Available
PRODUCT DESCRIPTION
The AD779 is a complete, multipurpose 14-bit monolithic
analog-to-digital converter, consisting of a sample-hold amplifier
(SHA), a microprocessor compatible bus interface, a voltage
reference and clock generation circuitry.
The AD779 is specified for ac (or “dynamic”) parameters such
as S/N+D ratio, THD and IMD which are important in signal
processing applications. In addition, the AD779K, B and T
grades are fully specified for dc parameters which are important
in measurement applications.
The 14 data bits are accessed by a 16-bit bus in a single read
operation. Data format is straight binary for unipolar mode and
twos complement binary for bipolar mode. The input has a full-
scale range of 10 V with a full power bandwidth of 1 MHz and a
full linear bandwidth of 500 kHz. High input impedance (10 MΩ)
allows direct connection to unbuffered sources without signal
degradation.
This product is fabricated on Analog Devices’ BiMOS process,
combining low power CMOS logic with high precision, low
noise bipolar circuits; laser-trimmed thin-film resistors provide
high accuracy. The converter utilizes a recursive subranging
algorithm which includes error correction and flash converter
circuitry to achieve high speed and resolution.
The AD779 operates from +5 V and ±12 V supplies and
dissipates 560 mW (typ). Twenty-eight-pin plastic DIP and
ceramic DIP packages are available.
*Protected by U.S. Patent Numbers 4,804,960; 4,814,767; 4,833,345;
4,250,445; 4,808,908; RE30,586.
PRODUCT HIGHLIGHTS
l. COMPLETE INTEGRATION: The AD779 minimizes
external component requirements by combining a high speed
sample-hold amplifier (SHA), ADC, 5 V reference, clock
and digital interface on a single chip. This provides a fully
specified sampling A/D function unattainable with discrete
designs.
2. SPECIFICATIONS: The AD779K, B and T grades provide
fully specified and tested ac and dc parameters. The AD779J,
A and S grades are specified and tested for ac parameters; dc
accuracy specifications are shown as typicals. DC specifica-
tions (such as INL, gain and offset) are important in control
and measurement applications. AC specifications (such as
S/N+D ratio, THD and IMD) are of value in signal process-
ing applications.
3. EASE OF USE: The pinout is designed for easy board lay-
out, and the single cycle read output provides compatibility
with 16-bit buses. Factory trimming eliminates the need for
calibration modes or external trimming to achieve rated
performance.
4. RELIABILITY: The AD779 utilizes Analog Devices’
monolithic BiMOS technology. This ensures long term
reliability compared to multichip and hybrid designs.
5. The AD779 is available in versions compliant with MIL-
STD-883. Refer to the Analog Devices Military Products
Databook or current AD779/883B data sheet for detailed
specifications.
