NSC ADC08234CIWMX, ADC08234CIWM, ADC08234CIMF, ADC08234BIWM, ADC08238CIWM Datasheet

TL/H/11015

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

with MUX, Reference, and Track/Hold

December 1994

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

TM

serial data exchange standard for easy interface to the
COPS

TM

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
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

C

e

4 MHz) 2 ms (Max)

Y

Power dissipation 20 mW (Max)

Y

Single supply 5 VDC(g5%)

Y

Total unadjusted error

g

(/2 LSB andg1 LSB

Y

Linearity Error (V

REF

e

2.5V)

g

(/2 LSB

Y

No missing codes (over temperature)

Y

On-board Reference

a

2.5Vg1.5% (Max)

ADC08238 Simplified Block Diagram

TL/H/11015– 4

TRI-STATEÉis a registered trademark of National Semiconductor Corporation.
COPS

TM

microcontrollers and MICROWIRETMare trademarks of National Semiconductor Corporation.

C

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

Ordering Information

Industrial

Package

(

b

40§CsT

A

s

a

85§C)

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

Connection Diagrams

ADC08238

SO and DIP

TL/H/11015– 1

ADC08231

DIP

TL/H/11015– 3

ADC08231

SO

TL/H/11015– 26

ADC08234

SO and DIP

TL/H/11015– 2

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

CC

) 6.5V

Voltage at Inputs and Outputs

b

0.3V to V

CC

a

0.3V

Input Current at Any Pin (Note 4)

g

5mA

Package Input Current (Note 4)

g

20 mA

Power Dissipation at T

A

e

25§C (Note 5) 800 mW

ESD Susceptibility (Note 6) 1500V

Soldering Information

N Package (10 sec.) 260

§

C

TSSOP and SO Package (Note 7):

Vapor Phase (60 sec.) 215

§

C

Infrared (15 sec.) 220

§

C

Storage Temperature

b

65§Ctoa150§C

Operating Ratings (Notes2&3)

Temperature Range T

MIN

s

T

A

s

T

MAX

ADC08231BIN, ADC08231CIN,

b

40§CsT

A

s

a

85§C

ADC08234BIN, ADC08234CIN,

ADC08238BIN, ADC08238CIN,

ADC08231BIWM, ADC08231CIWM,

ADC08234BIWM, ADC08238BIWM,

ADC08234CIWM, ADC08238CIWM,

ADC08234CIMF

Supply Voltage (V

CC

) 4.5 VDCto 6.3 V

DC

Electrical Characteristics

The following specifications apply for V

CC

ea

5VDC,V

REF

ea

2.5 VDCand f

CLK

e

4 MHz, R

Source

e

50X unless otherwise

specified. Boldface limits apply for T

A

e

T

J

e

T

MIN

to T

MAX

; all other limits T

A

e

T

J

e

25§C.

ADC08231,

ADC08234 and

ADC08238 with BIN,

Units

Symbol Parameter Conditions CIN, BIWM,

(Limits)

CIWM, or CIMF Suffixes

Typical Limits

(Note 8) (Note 9)

CONVERTER AND MULTIPLEXER CHARACTERISTICS

Linearity Error V

REF

ea

2.5 V

DC

BIN, BIWM

g

(/2 LSB (max)

CIN, CIMF, CIWM

g

1 LSB (max)

Gain Error V

REF

ea

2.5 V

DC

BIN, BIWM

g

1 LSB (max)

CIN, CIMF, CIWM

g

1 LSB (max)

Zero Error V

REF

ea

2.5 V

DC

BIN, BIWM

g

1 LSB (max)

CIN, CIMF, CIWM

g

1 LSB (max)

Total Unadjusted Error V

REF

ea

5V

DC

BIN, BIWM (Note 10)

g

1 LSB (max)

CIN, CIMF, CIWM

g

1 LSB (max)

Differential Linearity V

REF

ea

2.5 V

DC

8 Bits (min)

R

REF

Reference Input Resistance (Note 11) 3.5 kX

1.3 kX (min)

6.0 kX (max)

V

IN

Analog Input Voltage (Note 12) (V

CC

a

0.05) V (max)

(GND

b

0.05) V (min)

3

Electrical Characteristics (Continued)

The following specifications apply for V

CC

ea

5VDC,V

REF

ea

2.5 VDCand f

CLK

e

4 MHz, R

source

e

50X unless otherwise

specified. Boldface limits apply for T

A

e

T

J

e

T

MIN

to T

MAX

; all other limits T

A

e

T

J

e

25§C.

ADC08231,

ADC08234 and

ADC08238 with BIN,

Units

Symbol Parameter Conditions CIN, BIWM,

(Limits)

CIWM, or CIMF Suffixes

Typical Limits

(Note 8) (Note 9)

CONVERTER AND MULTIPLEXER CHARACTERISTICS (Continued)

DC Common-Mode Error V

REF

ea

2.5 V

DC

g

(/2 LSB (max)

Power Supply Sensitivity V

CC

ea

5Vg5%,

g

(/4 LSB (max)

V

REF

ea

2.5 V

DC

On Channel Leakage On Channele5V, 0.2

mA (max)

Current (Note 13) Off Channel

e

0V 1

On Channele0V,

b

0.2
mA (max)

Off Channele5V

b

1

Off Channel Leakage On Channele5V,

b

0.2
mA (max)

Current (Note 13) Off Channel

e

0V

b

1

On Channele0V, 0.2

mA (max)

Off Channel

e

5V 1

DYNAMIC CHARACTERISTICS (see Typical Converter Performance Characteristics)

S

NaD

Signal-to- V

REF

ea

5V

(Noise

a

Distortion) Sample Ratee286 kHz

Ratio V

IN

ea

5V

p-p

f

IN

e

10 kHz 48.35 dB

f

IN

e

50 kHz 48.00 dB

f

IN

e

100 kHz 47.40 dB

DIGITAL AND DC CHARACTERISTICS

V

IN(1)

Logical ‘‘1’’ Input Voltage V

CC

e

5.25V 2.0 V (min)

V

IN(0)

Logical ‘‘0’’ Input Voltage V

CC

e

4.75V 0.8 V (max)

I

IN(1)

Logical ‘‘1’’ Input Current V

IN

e

5.0V 1 mA (max)

I

IN(0)

Logical ‘‘0’’ Input Current V

IN

e

0V

b

1 mA (max)

V

OUT(1)

Logical ‘‘1’’ Output Voltage V

CC

e

4.75V:

I

OUT

eb

360 mA 2.4 V (min)

I

OUT

eb

10 mA 4.5 V (min)

V

OUT(0)

Logical ‘‘0’’ Output Voltage V

CC

e

4.75V 0.4 V (max)

I

OUT

e

1.6 mA

I

OUT

TRI-STATEÉOutput Current V

OUT

e

0V

b

3.0 mA (max)

V

OUT

e

5V 3.0 mA (max)

I

SOURCE

Output Source Current V

OUT

e

0V

b

6.5 mA (min)

I

SINK

Output Sink Current V

OUT

e

V

CC

8.0 mA (min)

I

CC

Supply Current CSeHIGH

ADC08234, ADC08238 3.0 mA (max)
ADC08231 (Note 16) 6.0 mA (max)

4

Electrical Characteristics (Continued)

The following specifications apply for V

CC

ea

5VDCand f

CLK

e

4 MHz unless otherwise specified. Boldface limits apply for

T

A

e

T

J

e

T

MIN

to T

MAX

; all other limits T

A

e

T

J

e

25§C.

ADC08231,

ADC08234 and

ADC08238 with BIN,

Units

Symbol Parameter Conditions CIN, BIWM,

(Limits)

CIWM, or CIMF Suffixes

Typical Limits

(Note 8) (Note 9)

REFERENCE CHARACTERISTICS

V

REF

OUT Output Voltage BIN, BIJ, 2.5

2.5

g

1.5%

V

BIWM

g

2%

CIN, CIJ, 2.5

2.5

g

3.0%

CIWM, CMJ

g

3.5%

DV

REF

/DT Temperature Coefficient 40 ppm/§C

DV

REF

/DI

L

Load Regulation Sourcing

%/mA

(max)

(Note 17) (0sI

L

s

a

4 mA)

ADC08234,

0.003 0.1

ADC08238

Sourcing
(0

s

I

L

s

a

2 mA)

ADC08231 0.003 0.1

Sinking
(b1sI

L

s

0 mA)

ADC08234,

0.2 0.5

ADC08238

Sinking
(

b

1sI

L

s

0 mA)

ADC08231 0.2 0.5

Line Regulation 4.75VsV

CC

s

5.25V

0.5 6

mV

(max)

I

SC

Short Circuit Current V

REF

e

0V

(max)

mA

ADC08234,

8 25

ADC08238

V

REF

e

0V

ADC08231 8 25

T

SU

Start-Up Time VCC:0Vx5V

20 ms

C

L

e

100 mF

DV

REF

/Dt Long Term Stability 200 ppm/1 kHr

5

Electrical Characteristics (Continued)

The following specifications apply for V

CC

ea

5VDC,V

REF

ea

2.5 VDCand t

r

e

t

f

e

20 ns unless otherwise specified.

Boldface limits apply for T

A

e

T

J

e

T

MIN

to T

MAX

; all other limits T

A

e

T

J

e

25§C.

Symbol Parameter Conditions

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

f

CLK

Clock Frequency 10 kHz (min)

4 MHz (max)

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

T

C

Conversion Time (Not Including f

CLK

e

4 MHz 8 1/f

CLK

(max)

MUX Addressing Time) 2 ms (max)

t

CA

Acquisition Time 1(/2 1/f

CLK

(max)

t

SELECT

CLK High while CS is High 50 ns

t

SET-UP

CS Falling Edge or Data Input

25 ns (min)

Valid to CLK Rising Edge

t

HOLD

Data Input Valid after CLK

20 ns (min)

Rising Edge

t

pd1,tpd0

CLK Falling Edge to Output C

L

e

100 pF:

Data Valid (Note 15) Data MSB First 250 ns (max)

Data LSB First 200 ns (max)

t1H,t

0H

TRI-STATE Delay from Rising Edge C

L

e

10 pF, R

L

e

10 kX

50 ns

of CS

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

C

L

e

100 pF, R

L

e

2kX 180 ns (max)

C

IN

Capacitance of Logic Inputs 5 pF

C

OUT

Capacitance of Logic Outputs 5 pF

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

e

DGNDe0VDC, unless otherwise specified.

Note 4: When the input voltage (V

IN

) at any pin exceeds the power supplies (V

IN

k

(AGND or DGND) or V

IN

l

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

J

MAX

, iJAand the ambient temperature, TA. The maximum

allowable power dissipation at any temperature is P

D

e

(T

J

MAX

b

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

with suffixes BIN, CIN, BIJ, CIJ, BIWM, and CIWM T

J

MAX

e

125§C. For devices with suffix CMJ, T

J

MAX

e

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

parts when board mounted follow: ADC08231 with BIN and CIN suffixes 120

§

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

167

§

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,

ADC08238 with BIWM and CIWM suffixes 91

§

C/W,

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

Linear Data Book

section ‘‘Surface Mount’’ for other methods of
soldering surface mount devices.
Note 8: Typicals are at T

J

e

25§C and represent the most likely parametric norm.

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

REF

ea

5V only applies to the ADC08234

and ADC08238. See Note 16.

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

IN(b)

t

V

IN(a)

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

for analog input voltages one diode drop below ground or one diode drop greater than V

CC

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

IN

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

be correct. Exceeding this range on an unselected channel will corrupt the reading of a selected channel. Achievement of an absolute 0 V

DC

to5VDCinput voltage

range will therefore require a minimum supply voltage of 4.950 V

DC

over temperature variations, initial tolerance and loading.
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

DC

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

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
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.

6

Typical Performance Characteristics

Reference Voltage

Linearity Error vs

Temperature

Linearity Error vs

Clock Frequency

Linearity Error vs

ADC08234)

Temperature (ADC08238,

Power Supply Current vs

Temperature

Output Current vs

vs Clock Frequency

Power Supply Current

Note: For ADC08231 add I

REF

(Note 16) TL/H/11015– 5

10 kHz Sine Wave Input

Spectral Response with

50 kHz Sine Wave Input

Spectral Response with

100 kHz Sine Wave Input

Spectral Response with

Ratio vs Input Frequency

Signal-to-Noise

a

Distortion

TL/H/11015– 6

7

Typical Reference Performance Characteristics

Load Regulation (3 Typical Parts)

Line Regulation

(3 Typical Parts)

vs Temperature

Output Drift

vs Supply Voltage

Output Current

Available

TL/H/11015– 7

8