Analog Devices ADADC84 5 b Datasheet

Fast, Complete

FEATURES

PERFORMANCE
Complete 12-bit A/D converter with reference and clock
Fast successive approximation conversion: 10 µs or 5 µs
Buried Zener reference for long-term stability and low

Gain TC: 10 ppm/°C
Max nonlinearity: < ±0.012%
Low power: 880 mW typ
Low chip count—high reliability
Industry-standard pinout
Z models for ±12 V operation available
MIL-STD-883B processing available

VERSATILITY
Negative true parallel logic outputs
Short cycle capability
Precision +6.3 V reference for external applications

PRODUCT DESCRIPTION

The AD ADC84/AD ADC85 series devices are high speed, low cost
12-bit successive approximation analog-to-digital converters that
include an internal clock, reference, and comparator. Its hybrid IC
design utilizes MSI digital and linear monolithic chips in
conjunction with a 12-bit monolithic DAC to provide modular
performance and versatility with IC size, price, and reliability.

12-Bit A/D Converters

AD ADC84/AD ADC85

Figure 1. Functional Block Diagram

The AD ADC84 and AD ADC85C are specified for operation over
the 0°C to +70°C temperature range. The AD ADC85 and
AD ADC85S are specified for the –25°C to +85°C and –55°C to
+125°C ranges, respectively. The serial output function is no longer
supported on the AD ADC84/AD ADC85 after date code 9623.

Important performance characteristics of the AD ADC84/
AD ADC85 series include maximum linearity error of ±0.012%;
gain TC below 15 ppm/°C at 25°C; typical power dissipation of
880 mW; and conversion time of less than 10 µs for the 12-bit
versions. Of considerable significance in severe and aerospace
applications is the guaranteed performance from –55°C to +125°C
of the AD ADC85S, which is also available with environmental
screening. Monotonic operation of the feedback DAC guarantees
no missing codes over temperature ranges of 0°C to +70°C, –25°C
to +85°C, and –55°C to +125°C.

The design of the AD ADC84/AD ADC85 includes scaling resistors
that provide analog input signal ranges of ±2.5 V, ±5 V, ±10 V, 0 V to
+5 V, or 0 V to +10 V. The 6.3 V precision reference, which can be
used for external applications, and the input buffer amplifier add
flexibility and value. All digital signals are fully DTL and TTL
compatible, and the data output is negative-true and available in
parallel form.

The AD ADC84/AD ADC85 are available in a performance grade
specified for 12-bit accuracy (±0.012% FSR max) with 10 µs
maximum conversion time.

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 that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.

PRODUCT HIGHLIGHTS

1. The AD ADC84/ AD ADC85 series devices are complete

12-bit ADCs. No external components are required to perform
a conversion.

2. The AD ADC84/ AD ADC85 directly replaces other devices of

this type with significant increases in performance.

3. The fast conversion rates of the AD ADC84 and AD ADC85

(10 μs) make them an excellent choice for applications
requiring high system throughput rates.

4. The internal buried Zener reference is laser trimmed to 6.3 V

±0.1% and ±10 ppm/°C typical TC. The reference is available
externally and can provide up to 1 mA.

5. The integrated package construction provides high quality and

reliability with small size and weight.

6. The monolithic 12-bit feedback DAC is used for reduced chip

count and higher reliability.

7. The AD ADC85S/883B comes processed to MIL-STD-883,

Class B requirements.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © 2003 Analog Devices, Inc. All rights reserved.

AD ADC84/AD ADC85

TABLE OF CONTENTS

Specifications..................................................................................... 3

Typical Performance Characteristics............................................. 5

Functional Description.................................................................... 6

Offset Adjustment ........................................................................ 6

Gain Adjustment........................................................................... 6

Theory of Operation.................................................................... 6

Timing............................................................................................ 6

Digital Output Data .....................................................................7

REVISION HISTORY

Revision B
11/03—Data Sheet changed from Rev. A to Rev. B

Removed AD5240...............................................................Universal

Updated format...................................................................Universal

Added text to PRODUCT DESCRIPTION.................................. 1

Updated OUTLINE DIMENSIONS............................................ 11

Input Scaling..................................................................................8

Input Voltage Range and LSB Values..........................................8

Calibration......................................................................................9

Grounding......................................................................................9

Clock Rate Control Alternate Connections............................ 10

Microprocessor Interfacing....................................................... 10

Outline Dimensions....................................................................... 11

Ordering Guide .......................................................................... 11

Rev. B | Page 2 of 12

AD ADC84/AD ADC85

SPECIFICATIONS

Table 1. Typical @ 25°C, ±15 V and +5 V, unless otherwise noted

Model AD ADC84 AD ADC85C AD ADC85 AD ADC85S Unit

RESOLUTION 12 12 12 12 Bits
ANALOG INPUTS

Voltage Ranges

Bipolar ±2.5, ±5, ±10 * * * V
Unipolar 0 to +5, 0 to +10 * * * V

Impedance (Direct Input)

0 V to +5 V, ±2.5 V 2.5 (±20%) * * * kΩ
0 V to +10 V, ±5 V 5 (±20%) * * * kΩ
±10 V 10 (±20%) * * * kΩ

Buffer Amplifier

Impedance (Min) 100 * * * MΩ
Bias Current 50 * * * nA
Settling Time

to 0.01% for 20 V Step 2 * * * µs

DIGITAL INPUTS

Convert Command

Logic Loading 1 * * * TTL Load
TRANSFER CHARACTERISTICS ERROR

Gain Error

Offset Error3 Adjustable to Zero * * *

Unipolar ±0.05 (±0.2% max) * * * % of FSR

Bipolar
Linearity Error (max)
Inherent Quantization Error ±0.5 * * * LSB
Differential Linearity Error ±0.5 * * * LSB
No Missing Codes

Temperature Range 0 to +70 0 to +70 –25 to +85 –55 to +125 °C
Power Supply Sensitivity

±15 V ±0.004 * * * % of FSR/% V

+5 V ±0.001 * * * % of FSR/% V

DRIFT

Specification Temperature Range 0 to +70 * –25 to +85 –55 to +125 °C
Gain (Max) ±30 ±25 ±15 ±25 ppm/°C
Offset

Unipolar ±3 * * ±5 max ppm/°C

Bipolar (Max)5 ±15 ±12 ±7 ±10 ppm/°C
Linearity ±3 * ±2 * ppm/°C
Monotonicity Guaranteed * * *

CONVERSION SPEED (MAX) 10 * * * µs

1

2

Positive Pulse 100 ns Min Trailing

* * *

Edge Initiates Conversion

3

5

6

±0.1 (±0.25% max) * * * %

4

±0.1 (±0.25% max) * * * % of FSR
±0.012 * * * % of FSR

Rev. B | Page 3 of 12

AD ADC84/AD ADC85

Model AD ADC84 AD ADC85C AD ADC85 AD ADC85S Unit

DIGITAL OUTPUT
(All Codes Complementary)

Parallel

Output Codes7

Unipolar CSB * * *
Bipolar COB, CTC * * *

Output Drive 2 * * * TTL Loads

Status Logic 1 during Conversion * * *

Status Output Drive 2 * * * TTL Loads

Internal Clock

Clock Output Drive 2 * * * TTL Loads
Frequency 1.9/1.22 * * * MHz

INTERNAL REFERENCE VOLTAGE 6.3/±15 mV max * * * V

Maximum External Current (with
No Degradation of Specifications) 1.0 * * * mA

Tempco of Drift (Max) ±20 max ±10 typ ±5 typ ±5 typ ppm/°C

POWER REQUIREMENTS

Rated Voltages +5, ±15 * * * V
Range for Rated Accuracy

Z Models8

Supply Drain

+15 V 25 Max * * * mA
–15 V 35 Max * * * mA
+5 V 140 Max * * * mA

Total Power Dissipation 1500 Max * * * mW

TEMPERATURE RANGE

Specification 0 to +70 * –25 to +85 –55 to +125 °C
Operating (Derated Specs) –25 to +85 * –55 to +125 –55 to +125 °C
Storage –55 to +125 * * * °C

PACKAGE OPTION9

DH-32F Ceramic Ceramic Ceramic Ceramic

*Specifications same as AD ADC84.

1

Buffer settling time adds to conversion speed when buffer is connected to input.

2

DTL/TTL compatible Logic 0 = 0.8 V max, Logic 1 = 2.0 V min for digital output, Logic 0 = 0.4 V max, Logic 1 = 2.4 V min.

3

Adjustable to zero.

4

FSR means full-scale range.

5

Guaranteed at VIN = 0 V.

6

Error shown is the same as ±1/2 LSB max error in % of FSR.

7

See Table 2.

8

For ±12 V operation, add Z to model number. Input range limited to a maximum of ±5 V.

9

For package outline information, see Outline Dimensions section.

+4.75 to +5.25 and
±13.5 to –16.5 * * * V

+4.75 to +5.25 and
±11.4 to –16.5 * * * V

Rev. B | Page 4 of 12