AD679 Datasheet, PDF (1/12 Pages) Analog Devices – 14-Bit 128 kSPS Complete Sampling ADC

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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 M⍀ Input Impedance
8-Bit Bus Interface (See AD779 for 16-Bit Interface)
On-Board Reference and Clock
10 V Unipolar or Bipolar Input Range
Pin Compatible with AD678 12-Bit, 200 kSPS ADC
MIL-STD-883 Compliant Versions Available
14-Bit 128 kSPS
Complete Sampling ADC
AD679*
FUNCTIONAL BLOCK DIAGRAM
GENERAL DESCRIPTION
The AD679 is a complete, multipurpose 14-bit monolithic
analog-to-digital converter, consisting of a sample-hold ampli-
fier (SHA), a microprocessor compatible bus interface, a voltage
reference and clock generation circuitry.
The AD679 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 AD679K, B and T
grades are fully specified for dc parameters which are important
in measurement applications.
The 14 data bits are accessed in two read operations (8+6), with
left justification. 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 im-
pedance (10 MΩ) allows direct connection to unbuffered
sources without signal degradation. Conversions can be initiated
either under microprocessor control or by an external clock
asynchronous to the system clock.
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 al-
gorithm which includes error correction and flash converter cir-
cuitry to achieve high speed and resolution.
The AD679 operates from +5 V and ± 12 V supplies and dissi-
pates 560 mW (typ). 28-pin plastic DIP, ceramic DIP and 44
J-leaded ceramic surface mount packages are available.
*Protected by U.S. Patent Nos. 4,804,960; 4,814,767; 4,833,345; 4,250,445;
4,808,908; RE 30,586
PRODUCT HIGHLIGHTS
1. COMPLETE INTEGRATION: The AD679 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 AD679K, B and T grades provide
fully specified and tested ac and dc parameters. The AD679J,
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 two read output provides compatibility with 8-
bit buses. Factory trimming eliminates the need for calibration
modes or external trimming to achieve rated performance.
4. RELIABILITY: The AD679 utilizes Analog Devices’ mono-
lithic BiMOS technology. This ensures long term reliability
compared to multichip and hybrid designs.
5. UPGRADE PATH: The AD679 provides the same pinout as
the 12-bit, 200 kSPS AD678 ADC.
6. The AD679 is available in versions compliant with MIL-
STD-883. Refer to the Analog Devices Military Products
Databook or current AD679/883B data sheet for detailed
specifications.
REV. C
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.
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