14-Bit 128 kSPS
Complete Sampling ADC
a
AD679
FUNCTIONAL BLOCK DIAGRAM
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
78 dB S/N+D (K, B, T Grades)
Twos Complement Data Format (Bipolar Mode)
Straight Binary Data Format (Unipolar Mode)
10 Mꢀ Input Impedance
8-Bit Bus 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
GENERAL DESCRIPTION
PRODUCT HIGHLIGHTS
The AD679 is a complete, multipurpose 14-bit monolithic
analog-to-digital converter, consisting of a sample-and-hold am-
plifier (SHA), a microprocessor-compatible bus interface, a volt-
age reference, and clock generation circuitry.
1. COMPLETE INTEGRATION: The AD679 minimizes
external component requirements by combining a high
speed sample-and-hold amplifier (SHA), ADC, 5 V refer-
ence, clock, and digital interface on a single chip. This
provides a fully specified sampling A/D function unattain-
able with discrete designs.
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 that are important in
measurement applications.
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.
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
impedance (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.
3. EASE OF USE: The pinout is designed for easy board layout,
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.
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 that includes error correction and flash converter
circuitry to achieve high speed and resolution.
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.
The AD679 operates from +5 V and 12 V supplies and dissipates
560 mW (typ). The part is available in 28-lead plastic DIP,
ceramic DIP, and 44 J-leaded ceramic surface-mount packages.
REV. D
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