National Semiconductor ADC08231, ADC08234, ADC08238 Technical data

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ADC08231/ADC08234/ADC08238 8-Bit 2 ms Serial I/O
A/D Converters with MUX, Reference, and Track/Hold

General Description

The ADC08231/ADC08234/ADC08238 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 interface to the

TM

COPS

family of controllers, and can easily interface with

standard shift registers or microprocessors.

Designed for high-speed/low-power applications, the devic­es are capable of a fast 2 ms conversion when used with a
4 MHz clock.

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 posi­tive 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-differ­ential modes. In addition, input voltage spans as small as 1V
can be accommodated.

Applications

Y

High-speed data acquisition

Y

Digitizing automotive sensors

Y

Process control/monitoring

Y

Remote sensing in noisy environments

Y

Disk drives

Y

Portable instrumentation

Y

Test systems

Features

Y

Serial digital data link requires few I/O pins

Y

Analog input track/hold function

Y

4- or 8-channel input multiplexer options with address

TM

logic

Y

On-chip 2.5V band-gap reference (g2% over tempera­ture guaranteed)

Y

No zero or full scale adjustment required

Y

TTL/CMOS input/output compatible

Y

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

Y

Pin compatible with Industry-Standards ADC0831/4/8

Key Specifications

Y

Resolution 8 Bits

Y

Conversion time (f

Y

Power dissipation 20 mW (Max)

Y

Single supply 5 VDC(g5%)

Y

Total unadjusted error

Y

Linearity Error (V

Y

No missing codes (over temperature)

Y

On-board Reference

e

4 MHz) 2 ms (Max)

C

g

(/2 LSB andg1 LSB

a

REF

e

2.5V)

December 1994

g

(/2 LSB

2.5Vg1.5% (Max)

ADC08231/ADC08234/ADC08238 8-Bit 2 ms Serial I/O A/D Converters

with MUX, Reference, and Track/Hold

ADC08238 Simplified Block Diagram

TRI-STATEÉis a registered trademark of National Semiconductor Corporation.

TM

COPS

microcontrollers and MICROWIRETMare trademarks of National Semiconductor Corporation.

C

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

TL/H/11015

TL/H/11015– 4

Ordering Information

Connection Diagrams

ADC08238

SO and DIP

b

(

40§CsT

Industrial

s

A

a

85§C)

Package

ADC08231BIN, ADC08231CIN N08E, DIP

ADC08234BIN, ADC08234CIN N14A, DIP

ADC08234CIMF MTB24, TSSOP

ADC08238BIN, ADC08238CIN N20A, DIP

ADC08231BIWM, ADC08231CIWM M14B, SO

ADC08234BIWM, ADC08234CIWM M14B, SO

ADC08238BIWM, ADC08238CIWM M20B, SO

ADC08234

SO and DIP

TL/H/11015– 2

ADC08231

DIP

ADC08231

SO

TL/H/11015– 1

TL/H/11015– 3

TL/H/11015– 26

ADC08234

TSSOP

TL/H/11015– 27

2

Absolute Maximum Ratings (Notes1&3)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.

Supply Voltage (V

Voltage at Inputs and Outputs

Input Current at Any Pin (Note 4)

Package Input Current (Note 4)

Power Dissipation at T

ESD Susceptibility (Note 6) 1500V

Soldering Information

N Package (10 sec.) 260
TSSOP and SO Package (Note 7):

Vapor Phase (60 sec.) 215
Infrared (15 sec.) 220

Storage Temperature

) 6.5V

CC

e

25§C (Note 5) 800 mW

A

b

0.3V to V

b

65§Ctoa150§C

CC

g

a

0.3V

g

5mA

20 mA

§

§

§

Operating Ratings (Notes2&3)

Temperature Range T

ADC08231BIN, ADC08231CIN,

ADC08234BIN, ADC08234CIN,

ADC08238BIN, ADC08238CIN,

ADC08231BIWM, ADC08231CIWM,

ADC08234BIWM, ADC08238BIWM,

ADC08234CIWM, ADC08238CIWM,

ADC08234CIMF

Supply Voltage (V

C

C
C

) 4.5 VDCto 6.3 V

CC

b

40§CsT

MIN

s

s

T

T

A

MAX

s

a

85§C

A

DC

Electrical Characteristics

The following specifications apply for V
specified. Boldface limits apply for T

CC

ea

5VDC,V

e

e

T

A

T

J

MIN

REF

to T

ea

MAX

2.5 VDCand f

; all other limits T

CLK

e

e

A

4 MHz, R

T

J

ADC08231,

ADC08234 and

ADC08238 with BIN,

Symbol Parameter Conditions CIN, BIWM,

CIWM, or CIMF Suffixes

Typical Limits

(Note 8) (Note 9)

CONVERTER AND MULTIPLEXER CHARACTERISTICS

Linearity Error V

BIN, BIWM

REF

ea

2.5 V

DC

CIN, CIMF, CIWM

Gain Error V

BIN, BIWM

REF

ea

2.5 V

DC

CIN, CIMF, CIWM

Zero Error V

BIN, BIWM

REF

ea

2.5 V

DC

CIN, CIMF, CIWM

Total Unadjusted Error V

BIN, BIWM (Note 10)

REF

ea

5V

DC

CIN, CIMF, CIWM

Differential Linearity V

R

REF

V

IN

Reference Input Resistance (Note 11) 3.5 kX

Analog Input Voltage (Note 12) (V

REF

ea

2.5 V

DC

e

50X unless otherwise

Source

e

25§C.

g

(/2 LSB (max)

g

1 LSB (max)

g

1 LSB (max)

g

1 LSB (max)

g

1 LSB (max)

g

1 LSB (max)

g

1 LSB (max)

g

1 LSB (max)

8 Bits (min)

1.3 kX (min)

6.0 kX (max)

a

0.05) V (max)

CC

b

(GND

0.05) V (min)

Units

(Limits)

3

Electrical Characteristics (Continued)

The following specifications apply for V
specified. Boldface limits apply for T

CC

A

ea

e

T

J

5VDC,V

e

T

MIN

REF

to T

ea

MAX

2.5 VDCand f

; all other limits T

CLK

e

e

A

4 MHz, R

e

T

J

ADC08231,

ADC08234 and

ADC08238 with BIN,

Symbol Parameter Conditions CIN, BIWM,

CIWM, or CIMF Suffixes

Typical Limits

(Note 8) (Note 9)

CONVERTER AND MULTIPLEXER CHARACTERISTICS (Continued)

DC Common-Mode Error V

Power Supply Sensitivity V

ea

ea

ea

2.5 V

DC

5Vg5%,

2.5 V

DC

REF

CC

V

REF

On Channel Leakage On Channele5V, 0.2
Current (Note 13) Off Channel

e

0V 1

On Channele0V,
Off Channele5V

Off Channel Leakage On Channele5V,
Current (Note 13) Off Channel

e

0V

On Channele0V, 0.2
Off Channel

e

5V 1

DYNAMIC CHARACTERISTICS (see Typical Converter Performance Characteristics)

S

NaD

Signal-to- V

a

(Noise

Distortion) Sample Ratee286 kHz

Ratio V

ea

REF

IN

f

IN

f

IN

f

IN

5V

ea

5V

p-p

e

10 kHz 48.35 dB

e

50 kHz 48.00 dB

e

100 kHz 47.40 dB

DIGITAL AND DC CHARACTERISTICS

V

IN(1)

V

IN(0)

I

IN(1)

I

IN(0)

V

OUT(1)

V

OUT(0)

I

OUT

I

SOURCE

I

SINK

I

CC

Logical ‘‘1’’ Input Voltage V

Logical ‘‘0’’ Input Voltage V

Logical ‘‘1’’ Input Current V

Logical ‘‘0’’ Input Current V

Logical ‘‘1’’ Output Voltage V

Logical ‘‘0’’ Output Voltage V

TRI-STATEÉOutput Current V

Output Source Current V

Output Sink Current V

Supply Current CSeHIGH

ADC08234, ADC08238 3.0 mA (max)

e

5.25V 2.0 V (min)

CC

e

4.75V 0.8 V (max)

CC

e

5.0V 1 mA (max)

IN

e

0V

IN

e

4.75V:

CC

eb

I

OUT

I

OUT

I

OUT

V

360 mA 2.4 V (min)

eb

10 mA 4.5 V (min)

e

4.75V 0.4 V (max)

CC

e

1.6 mA

e

0V

OUT

e

5V 3.0 mA (max)

OUT

e

0V

OUT

e

V

OUT

CC

ADC08231 (Note 16) 6.0 mA (max)

e

source

25§C.

g

g

b

b

b

b

b

b

3.0 mA (max)

b

6.5 mA (min)

8.0 mA (min)

50X unless otherwise

Units

(Limits)

(/2 LSB (max)

(/4 LSB (max)

mA (max)

0.2

1

0.2

1

mA (max)

mA (max)

mA (max)

1 mA (max)

4

Electrical Characteristics (Continued)

The following specifications apply for V

e

T

e

T

T

to T

A

J

MIN

; all other limits T

MAX

CC

ea

A

5VDCand f

e

e

T

J

25§C.

e

4 MHz unless otherwise specified. Boldface limits apply for

CLK

ADC08234 and

ADC08238 with BIN,

Symbol Parameter Conditions CIN, BIWM,

CIWM, or CIMF Suffixes

Typical Limits

(Note 8) (Note 9)

REFERENCE CHARACTERISTICS

V

OUT Output Voltage BIN, BIJ, 2.5

REF

BIWM

g

2%

CIN, CIJ, 2.5

g

CIWM, CMJ

DV

/DT Temperature Coefficient 40 ppm/§C

REF

DV

REF

/DI

Load Regulation Sourcing

L

(Note 17) (0sI

s

L

ADC08234,

a

4 mA)

ADC08238

3.5%

0.003 0.1

Sourcing

s

s

(0
ADC08231 0.003 0.1

a

I

2 mA)

L

Sinking
(b1sI
ADC08234,
ADC08238

s

0 mA)

L

0.2 0.5

Sinking

s

b

(

1sI

0 mA)

L

ADC08231 0.2 0.5

e

0V

e

0V

100 mF

CC

s

5.25V

0.5 6

8 25

20 ms

Line Regulation 4.75VsV

I

SC

Short Circuit Current V

REF

ADC08234,
ADC08238

V

REF

ADC08231 8 25

T

SU

DV

/Dt Long Term Stability 200 ppm/1 kHr

REF

Start-Up Time VCC:0Vx5V

e

C

L

ADC08231,

2.5

2.5

g

g

Units

(Limits)

1.5%

V

3.0%

%/mA

(max)

mV

(max)

mA

(max)

5

Electrical Characteristics (Continued)

The following specifications apply for V

Boldface limits apply for T

Symbol Parameter Conditions

f

CLK

Clock Frequency 10 kHz (min)

e

T

A

ea

5VDC,V

CC

e

T

MIN

to T

MAX

J

ea

REF

; all other limits T

2.5 VDCand t

e

e

t

r

e

e

T

A

J

20 ns unless otherwise specified.

f

25§C.

Typical Limits Units
(Note 8) (Note 9) (Limits)

4 MHz (max)

Clock Duty Cycle 40 % (min)
(Note 14) 60 % (max)

T

C

t

CA

t

SELECT

t

SET-UP

t

HOLD

t

pd1,tpd0

Conversion Time (Not Including f
MUX Addressing Time) 2 ms (max)

Acquisition Time 1(/2 1/f

CLK High while CS is High 50 ns

CS Falling Edge or Data Input
Valid to CLK Rising Edge

Data Input Valid after CLK
Rising Edge

CLK Falling Edge to Output C
Data Valid (Note 15) Data MSB First 250 ns (max)

e

4 MHz 8 1/f

CLK

e

100 pF:

L

(max)

CLK

(max)

CLK

25 ns (min)

20 ns (min)

Data LSB First 200 ns (max)

t1H,t

C

IN

C

OUT

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 2: Operating Ratings indicate conditions for which the device is functional. These ratings do not guarantee specific performance limits. For guaranteed

specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance
characteristics may degrade when the device is not operated under the listed test conditions.

Note 3: All voltages are measured with respect to AGND
Note 4: When the input voltage (V

5 mA. The 20 mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four
pins.

Note 5: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
allowable power dissipation at any temperature is P
with suffixes BIN, CIN, BIJ, CIJ, BIWM, and CIWM T
parts when board mounted follow: ADC08231 with BIN and CIN suffixes 120
167

§

ADC08238 with BIWM and CIWM suffixes 91

Note 6: Human body model, 100 pF capacitor discharged through a 1.5 kX resistor.
Note 7: See AN450 ‘‘Surface Mounting Methods and Their Effect on Product Reliability’’ or

soldering surface mount devices.

Note 8: Typicals are at T
Note 9: Guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 10: Total unadjusted error includes zero, full-scale, linearity, and multiplexer error. Total unadjusted error with V

and ADC08238. See Note 16.

Note 11: Cannot be tested for the ADC08231.
Note 12: For V

for analog input voltages one diode drop below ground or one diode drop greater than V
inputs (e.g., 5V) can cause an input diode to conduct, especially at elevated temperatures. This will cause errors for analog inputs near full-scale. The specification
allows 50 mV forward bias of either diode; this means that as long as the analog V
be correct. Exceeding this range on an unselected channel will corrupt the reading of a selected channel. Achievement of an absolute 0 V
range will therefore require a minimum supply voltage of 4.950 V

Note 13: Channel leakage current is measured after a single-ended channel is selected and the clock is turned off. For off channel leakage current the following
two cases are considered: one, with the selected channel tied high (5 V
channels is measured; two, with the selected channel tied low and the off channels tied high, total current flow through the off channels is again measured. The two
cases considered for determining on channel leakage current are the same except total current flow through the selected channel is measured.

Note 14: A 40% to 60% duty cycle range insures proper operation at all clock frequencies. In the case that an available clock has a duty cycle outside of these
limits the minimum time the clock is high or low must be at least 120 ns. The maximum time the clock can be high or low is 100 m s.

Note 15: Since data, MSB first, is the output of the comparator used in the successive approximation loop, an additional delay is built in (see Block Diagram) to
allow for comparator response time.

Note 16: For the ADC08231 V
reference current (700 mA typical, 2 mA maximum).

Note 17: Load regulation test conditions and specifications for the ADC08231 differ from those of the ADC08234 and ADC08238 because the ADC08231 has the
on-board reference as a permanent load.

TRI-STATE Delay from Rising Edge C

0H

of CS

to Data Output and SARS Hi-Z (see TRI-STATE Test Circuits)

Capacitance of Logic Inputs 5 pF

Capacitance of Logic Outputs 5 pF

C/W,

e

e

(T

D

J

MAX

e

J

MAX

) at any pin exceeds the power supplies (V

IN

C/W, ADC08238 with BIN and CIN suffixes 80§C/W. ADC08231 with BIWM and CIWM suffixes 140§C/W, ADC08234 with BIWM and CIWM suffixes 140§C/W,

e

25§C and represent the most likely parametric norm.

J

t

V

IN(b)

the digital code will be 0000 0000. Two on-chip diodes are tied to each analog input (see Block Diagram) which will forward-conduct

IN(a)

REF

§

IN is internally tied to the on chip 2.5V band-gap reference output; therefore, the supply current is larger because it includes the

e

10 pF, R

L

e

C

100 pF, R

L

DGNDe0VDC, unless otherwise specified.

b

TA)/iJAor the number given in the Absolute Maximum Ratings, whichever is lower. For devices

125§C. For devices with suffix CMJ, T

over temperature variations, initial tolerance and loading.

DC

) and the remaining off channels tied low (0 VDC), total current flow through the off

DC

e

10 kX

L

e

2kX 180 ns (max)

L

k

(AGND or DGND) or V

IN

J

MAX

J

C/W, ADC08234 with BIN and CIN suffixes 95§C/W, ADC08234 with CIMF suffix

§

does not exceed the supply voltage by more than 50 mV, the output code will

IN

MAX

Linear Data Book

supply. During testing at low VCClevels (e.g., 4.5V), high level analog

CC

50 ns

l

AVCC,) the current at that pin should be limited to

IN

, iJAand the ambient temperature, TA. The maximum

e

150§C. The typical thermal resistances (iJA) of these

section ‘‘Surface Mount’’ for other methods of

ea

5V only applies to the ADC08234

REF

to5VDCinput voltage

DC

6

Typical Performance Characteristics

Linearity Error vs
Reference Voltage

Power Supply Current vs
Temperature (ADC08238,
ADC08234)

Note: For ADC08231 add I

Spectral Response with
10 kHz Sine Wave Input

Linearity Error vs
Temperature

Output Current vs
Temperature

(Note 16) TL/H/11015– 5

REF

Spectral Response with
50 kHz Sine Wave Input

Linearity Error vs
Clock Frequency

Power Supply Current
vs Clock Frequency

Spectral Response with
100 kHz Sine Wave Input

a

Signal-to-Noise

Distortion

Ratio vs Input Frequency

7

TL/H/11015– 6

Typical Reference Performance Characteristics

Line Regulation

Load Regulation (3 Typical Parts)

Available
Output Current
vs Supply Voltage

Output Drift
vs Temperature
(3 Typical Parts)

TL/H/11015– 7

8