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TL/H/10555

ADC08031/ADC08032/ADC08034/ADC08038 8-Bit High-Speed Serial I/O A/D Converters with

Multiplexer Options, Voltage Reference, and Track/Hold Function

January 1995

ADC08031/ADC08032/ADC08034/ADC08038 8-Bit

High-Speed Serial I/O A/D Converters with Multiplexer

Options, Voltage Reference, and Track/Hold Function

General Description

The ADC08031/ADC08032/ADC08034/ADC08038 are

8-bit successive approximation A/D converters with serial I/

O and configurable input multiplexers with up to 8 channels.

The serial I/O is configured to comply with the NSC

MICROWIRE

serial data exchange standard for easy in-

terface to the COPS

family of controllers, and can easily

interface with standard shift registers or microprocessors.

The ADC08034 and ADC08038 provide a 2.6V band-gap

derived reference. For devices offering guaranteed voltage

reference performance over temperature see ADC08131,

ADC08134 and ADC08138.

A track/hold function allows the analog voltage at the posi-

tive input to vary during the actual A/D conversion.

The analog inputs can be configured to operate in various

combinations of single-ended, differential, or pseudo-differ-

ential modes. In addition, input voltage spans as small as 1V

can be accommodated.

Applications

Digitizing automotive sensors

Process control monitoring

Remote sensing in noisy environments

Instrumentation

Test systems

Embedded diagnostics

Features

Serial digital data link requires few I/O pins

Analog input track/hold function

2-, 4-, or 8-channel input multiplexer options with ad-

dress logic

0V to 5V analog input range with single 5V power

supply

No zero or full scale adjustment required

TTL/CMOS input/output compatible

On chip 2.6V band-gap reference

0.3

standard width 8-, 14-, or 20-pin DIP package

14-, 20-pin small-outline packages

Key Specifications

Resolution 8 bits

Conversion time (f

1 MHz) 8ms (max)

Power dissipation 20mW (max)

Single supply 5V

(

5%)

Total unadjusted error

(/2 LSB and

1LSB

No missing codes over temperature

TRI-STATE

is a registered trademark of National Semiconductor Corporation.

COPS

microcontrollers and MICROWIRE

are trademarks of National Semiconductor

Corporation.

Ordering Information

Industrial (

C) Package

ADC08031BIN, ADC08031CIN N08E

ADC08032BIN, ADC08032CIN N08E

ADC08034BIN, ADC08034CIN N14A

ADC08038BIN, ADC08038CIN N20A

ADC08031BIWM, ADC08031CIWM,

ADC08032BIWM, ADC08032CIWM, M14B

ADC08034BIWM, ADC08034CIWM

ADC08038BIWM, ADC08038CIWM M20B

1995 National Semiconductor Corporation RRD-B30M75/Printed in U. S. A.

Summary of content (24 pages)

PAGE 1
ADC08031/ADC08032/ADC08034/ADC08038 8-Bit High-Speed Serial I/O A/D Converters with Multiplexer Options, Voltage Reference, and Track/Hold Function General Description Features The ADC08031/ADC08032/ADC08034/ADC08038 are 8-bit successive approximation A/D converters with serial I/ O and configurable input multiplexers with up to 8 channels.
PAGE 2
Connection Diagrams ADC08038 ADC08034 TL/H/10555 – 3 TL/H/10555–2 ADC08032 Dual-In-Line Package ADC08031 Dual-In-Line Package TL/H/10555–4 TL/H/10555 – 5 ADC08032 Small Outline Package ADC08031 Small Outline Package TL/H/10555–30 TL/H/10555 – 31 2
PAGE 3
Absolute Maximum Ratings (Notes 1 & 3) Operating Ratings (Notes 2 & 3) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications.
PAGE 4
Electrical Characteristics (Continued) The following specifications apply for VCC e VREF e a 5 VDC, and fCLK e 1 MHz unless otherwise specified. Boldface limits apply for TA e TJ e TMIN to TMAX; all other limits TA e TJ e 25§ C. Symbol Parameter Conditions ADC08031, ADC08032, ADC08034 and ADC08038 with BIN, CIN, BIWM or CIWM Suffixes Typical (Note 8) Units (Limits) Limits (Note 9) DIGITAL AND DC CHARACTERISTICS VIN(1) Logical ‘‘1’’ Input Voltage VCC e 5.25V 2.
PAGE 5
Electrical Characteristics (Continued) The following specifications apply for VCC e VREF e a 5 VDC, and tr e tf e 20 ns unless otherwise specified. Boldface limits apply for TA e TJ e TMIN to TMAX; all other limits TA e TJ e 25§ C.
PAGE 6
Typical Performance Characteristics Linearity Error vs Reference Voltage Linearity Error vs Temperature Linearity Error vs Clock Frequency Power Supply Current vs Temperature (ADC08038, ADC08034, ADC08031) Output Current vs Temperature Power Supply Current vs Clock Frequency TL/H/10555 – 6 Note: For ADC08032 add IREF Leakage Current Test Circuit TL/H/10555 – 7 6
PAGE 7
TRI-STATE Test Circuits and Waveforms t1H t1H t0H t0H TL/H/10555 – 8 TL/H/10555 – 9 Timing Diagrams Data Input Timing TL/H/10555 – 10 *To reset these devices, CLK and CS must be simultaneously high for a period of tSELECT or greater. Otherwise these devices are compatible with industry standards ADC0831/2/4/8.
PAGE 8
Timing Diagrams (Continued) ADC08031 Timing TL/H/10555 – 13 *LSB first output not available on ADC08031. LSB information is maintained for remainder of clock periods until CS goes high.
PAGE 9
*Make sure clock edge Ý18 clocks in the LSB before SE is taken low ADC08038 Timing TL/H/10555 – 16 Timing Diagrams (Continued) 9
PAGE 10
Note 1: For the ADC08034, the ‘‘SEL 1’’ Flip-Flop is bypassed, for the ADC08032, both ‘‘SEL 0’’ and ‘‘SEL 1’’ Flip-Flops are bypassed. *Some of these functions/pins are not available with other options.
PAGE 11
Functional Description 1.0 MULTIPLEXER ADDRESSING differentially with any other channel. In addition to selecting differential mode the polarity may also be selected. Channel 0 may be selected as the positive input and channel 1 as the negative input or vice versa. This programmability is best illustrated by the MUX addressing codes shown in the following tables for the various product options. The MUX address is shifted into the converter via the DI line.
PAGE 12
Functional Description (Continued) TABLE II. MUX Addressing: ADC08038 (Continued) Differential MUX Mode MUX Address Analog Differential Channel-Pair Ý SGL/ DIF ODD/ SIGN 1 0 0 1 1 0 0 0 0 a b 1 0 0 0 1 1 0 0 1 0 1 0 0 1 1 1 0 1 0 0 1 0 1 0 1 1 0 1 1 0 1 0 1 1 1 START SELECT 0 b 1 2 2 3 a b 5 a b 7 a b b a a b TABLE III. MUX Addressing: ADC08034 Single-Ended MUX Mode a TABLE IV.
PAGE 13
Functional Description (Continued) To understand the operation of these converters it is best to refer to the Timing Diagrams and Functional Block Diagram and to follow a complete conversion sequence. For clarity a separate timing diagram is shown for each device. 1. A conversion is initiated by pulling the CS (chip select) line low. This line must be held low for the entire conversion. The converter is now waiting for a start bit and its MUX assignment word. 2.
PAGE 14
Functional Description (Continued) The DI and DO lines can be tied together and controlled through a bidirectional processor I/O bit with one wire. This is possible because the DI input is only ‘‘looked-at’’ during the MUX addressing interval while the DO line is still in a high impedance state. 3. When the start bit has been shifted into the start location of the MUX register, the input channel has been assigned and a conversion is about to begin.
PAGE 15
Functional Description (Continued) The zero error of the A/D converter relates to the location of the first riser of the transfer function and can be measured by grounding the VIN (b) input and applying a small magnitude positive voltage to the VIN ( a ) input. Zero error is the difference between the actual DC input voltage which is necessary to just cause an output digital code transition from 0000 0000 to 0000 0001 and the ideal (/2 LSB value ((/2 LSB e 9.8mV for VREF e 5.000VDC). 4.
PAGE 16
Applications A ‘‘Stand-Alone’’ Hook-Up for ADC08038 Evaluation *Pinouts shown for ADC08038. For all other products tie to pin functions as shown.
PAGE 17
Applications (Continued) Digitizing a Current Flow TL/H/10555 – 22 Operating with Ratiometric Transducers *VIN( b ) e 0.
PAGE 18
Applications (Continued) Span Adjust; 0V s VIN s 3V Zero-Shift and Span Adjust: 2V s VIN s 5V TL/H/10555 – 24 18
PAGE 19
Applications (Continued) High Accuracy Comparators Protecting the Input DO e all 1s if a VIN l b VIN DO e all 0s if a VIN k b VIN TL/H/10555 – 26 Diodes are 1N914 TL/H/10555 – 25 Digital Load Cell TL/H/10555 – 27 # # # # Uses one more wire than load cell itself Two mini-DIPs could be mounted inside load cell for digital output transducer Electronic offset and gain trims relax mechanical specs for gauge factor and offset Low level cell output is converted immediately for high noise immunity 19
PAGE 20
Applications (Continued) 4 mA–20 mA Current Loop Converter # All power supplied by loop # 1500V isolation at output TL/H/10555 – 28 Isolated Data Converter # No power required remotely # 1500V isolation 20 TL/H/10555 – 29
PAGE 21
Physical Dimensions inches (millimeters) Order Number ADC08031BIWM, ADC08031CIWM,ADC08032BIWM, ADC08032CIWM, ADC08034BIWM or ADC08034CIWM NS Package Number M14B 21
PAGE 22
Physical Dimensions inches (millimeters) (Continued) Order Number ADC08038BIWM or ADC08038CIWM NS Package Number M20B Order Number ADC08031BIN, ADC08031CIN, ADC08032BIN or ADC08032CIN NS Package Number N08E 22
PAGE 23
Physical Dimensions inches (millimeters) (Continued) Order Number ADC08034BIN or ADC08034CIN NS Package Number N14A 23
PAGE 24
ADC08031/ADC08032/ADC08034/ADC08038 8-Bit High-Speed Serial I/O A/D Converters with Multiplexer Options, Voltage Reference, and Track/Hold Function Physical Dimensions inches (millimeters) (Continued) Order Number ADC08038CIN or ADC08038BIN NS Package Number N20A LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1.