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TL/H/10749

ADC08131/ADC08134/ADC08138 8-Bit High-Speed Serial I/O A/D Converters

with Multiplexer Options, Voltage Reference, and Track/Hold Function

December 1994

ADC08131/ADC08134/ADC08138 8-Bit High-Speed

Serial I/O A/D Converters with Multiplexer Options,

Voltage Reference, and Track/Hold Function

General Description

The ADC08131/ADC08134/ADC08138 are 8-bit succes-

sive approximation A/D converters with serial I/O and con-

figurable 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 interface to the

COPS

family of controllers, and can easily interface with

standard shift registers or microprocessors.

All three devices provide a 2.5V band-gap derived reference

with guaranteed performance over temperature.

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

Embedded diagnostics

Features

Serial digital data link requires few I/O pins

Analog input track/hold function

4- or 8-channel input multiplexer options with address

logic

On-chip 2.5V band-gap reference (

2% over tempera-

ture guaranteed)

No zero or full scale adjustment required

TTL/CMOS input/output compatible

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

supply

Key Specifications

Resolution 8 Bits

Conversion time (f

1 MHz) 8 ms (Max)

Power dissipation 20 mW (Max)

Single supply 5 V

(

5%)

Total unadjusted error

(/2 LSB and

1 LSB

Linearity Error (V

REF

2.5V)

(/2 LSB

No missing codes (over temperature)

On-board Reference

2.5V

1.5% (Max)

Ordering Information

Industrial

Package

(

ADC08131BIN, ADC08131CIN N08E

ADC08134BIN, ADC08134CIN N14A

ADC08138BIN, ADC08138CIN N20A

ADC08134BIWM, ADC08134CIWM M14B

ADC08138BIWM, ADC08138CIWM M20B

Connection Diagrams

ADC08138

Dual-In-Line and

Small Outline

Packages

TL/H/10749–2

ADC08134

Dual-In-Line and

Small Outline

Packages

TL/H/10749–3

ADC08131

Dual-In-Line Package

TL/H/10749–4

TRI-STATE

is a registered trademark of National Semiconductor Corporation.

COPS

microcontrollers and MICROWIRE

are trademarks of National Semiconductor Corporation.

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

Summary of content (22 pages)

PAGE 1
ADC08131/ADC08134/ADC08138 8-Bit High-Speed Serial I/O A/D Converters with Multiplexer Options, Voltage Reference, and Track/Hold Function General Description Features The ADC08131/ADC08134/ADC08138 are 8-bit successive approximation A/D converters with serial I/O and configurable input multiplexers with up to 8 channels.
PAGE 2
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. Temperature Range ADC08131BIN, ADC08131CIN, TMIN s TA s TMAX b 40§ C s TA s a 85§ C ADC08134BIN, ADC08134CIN, ADC08138BIN, ADC08138CIN, ADC08134BIWM, ADC08138BIWM, ADC08134CIWM, ADC08138CIWM Supply Voltage (VCC) Supply Voltage (VCC) 6.5V b 0.3V to VCC a 0.
PAGE 3
Electrical Characteristics (Continued) The following specifications apply for VCC e a 5 VDC, VREF e a 2.5 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 ADC08131, ADC08134 and ADC08138 with BIN, CIN, BIWM or CIWM Suffixes Typical (Note 8) Units (Limits) Limits (Note 9) CONVERTER AND MULTIPLEXER CHARACTERISTICS (Continued) DC Common-Mode Error VREF e 2.
PAGE 4
Electrical Characteristics (Continued) The following specifications apply for VCC 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 ADC08131, ADC08134 and ADC08138 with BIN, CIN, BIWM or CIWM Suffixes Typical (Note 8) Units (Limits) Limits (Note 9) REFERENCE CHARACTERISTICS VREFOUT Output Voltage ADC08134, ADC08138 2.
PAGE 5
Electrical Characteristics (Continued) The following specifications apply for VCC e a 5 VDC, VREF e a 2.5 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
ADC08138 Simplified Block Diagram TL/H/10749 – 1 6
PAGE 7
Typical Converter Performance Characteristics Linearity Error vs Reference Voltage Linearity Error vs Temperature Linearity Error vs Clock Frequency Power Supply Current vs Temperature (ADC08138, ADC08134) Output Current vs Temperature Power Supply Current vs Clock Frequency Note: For ADC08131 add IREF (Note 16) TL/H/10749 – 5 Typical Reference Performance Characteristics Load Regulation Line Regulation (3 Typical Parts) Output Drift vs Temperature (3 Typical Parts) Available Output Current vs Su
PAGE 8
TRI-STATE Test Circuits and Waveforms t1H t1H t0H t0H TL/H/10749–7 TL/H/10749 – 8 Timing Diagrams Data Input Timing TL/H/10749 – 9 *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 ADC0831/4/8.
PAGE 9
Timing Diagrams (Continued) ADC08131 Timing TL/H/10749 – 12 *LSB first output not available on ADC08131. LSB information is maintained for remainder of clock periods until CS goes high.
PAGE 10
*Make sure clock edge Ý18 clocks in the LSB before SE is taken low ADC08138 Timing TL/H/10749 – 14 Timing Diagrams (Continued) 10
PAGE 11
Note 1: For the ADC08134, the ‘‘SEL 1’’ Flip-Flop is bypassed. For the ADC08131, VREFOUT and VREFIN are internally tied together. *Some of these functions/pins are not available with other options.
PAGE 12
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 13
Functional Description (Continued) TABLE II.
PAGE 14
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 15
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 16
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 17
Applications A ‘‘Stand-Alone’’ Hook-Up for ADC08138 Evaluation *Pinouts shown for ADC08138. For all other products tie to pin functions as shown.
PAGE 18
Applications (Continued) Protecting the Input Diodes are 1N914 TL/H/10749 – 22 Operating with Ratiometric Transducers *VIN( b ) e 0.
PAGE 19
Applications (Continued) Zero-Shift and Span Adjust: 2V s VIN s 5V TL/H/10749 – 25 Physical Dimensions inches (millimeters) Order Number ADC08134BIWM or ADC08134CIWM NS Package Number M14B 19
PAGE 20
Physical Dimensions inches (millimeters) (Continued) Order Number ADC08138BIWM or ADC08138CIWM NS Package Number M20B Order Number ADC08131BIN or ADC08131CIN NS Package Number N08E 20
PAGE 21
Physical Dimensions inches (millimeters) (Continued) Order Number ADC08134BIN or ADC08134CIN NS Package Number N14A 21
PAGE 22
ADC08131/ADC08134/ADC08138 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 ADC08138CIN or ADC08138BIN 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.