FUNCTIONAL BLOCK DIAGRAM

REV. B

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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 M

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 M

Ω)

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.