TEXAS INSTRUMENTS ADS7841 Technical data

ADS7841

ADS7841

ADS7841

SBAS084B – JULY 2001

12-Bit, 4-Channel Serial Output Sampling

ANALOG-TO-DIGITAL CONVERTER

FEATURES

● SINGLE SUPPLY: 2.7V to 5V

● 4-CHANNEL SINGLE-ENDED OR

2-CHANNEL DIFFERENTIAL INPUT

● UP TO 200kHz CONVERSION RATE

● ±1LSB MAX INL AND DNL

● NO MISSING CODES

● 72dB SINAD

● SERIAL INTERFACE

● DIP-16 OR SSOP-16 PACKAGE

● ALTERNATE SOURCE FOR MAX1247

● ADS7841ES: +125°C Version

APPLICATIONS

● DATA ACQUISITION

● TEST AND MEASUREMENT

● INDUSTRIAL PROCESS CONTROL

● PERSONAL DIGITAL ASSISTANTS

● BATTERY-POWERED SYSTEMS

DESCRIPTION

The ADS7841 is a 4-channel, 12-bit sampling Analog-to­Digital Converter (ADC) with a synchronous serial inter­face. The resolution is programmable to either 8 bits or 12
bits. Typical power dissipation is 2mW at a 200kHz through­put rate and a +5V supply. The reference voltage (V
be varied between 100mV and VCC, providing a correspond­ing input voltage range of 0V to V

. The device includes

REF

a shutdown mode which reduces power dissipation to under
15µW. The ADS7841 is tested down to 2.7V operation.

Low power, high speed, and on-board multiplexer make the
ADS7841 ideal for battery-operated systems such as per­sonal digital assistants, portable multi-channel data loggers,
and measurement equipment. The serial interface also pro­vides low-cost isolation for remote data acquisition. The
ADS7841 is available in a DIP-16 or a SSOP-16 package
and is specified over the –40°C to +125°C

(1)

temperature

range.

NOTE: (1) ES grade only.

REF

) can

CH0
CH1
CH2
CH3

COM

V

REF

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.

Four

Channel

Multiplexer

CDAC

SAR

www.ti.com

Comparator

DCLK

CS

Serial

Interface

and

Control

Copyright © 2000, Texas Instruments Incorporated

SHDN
DIN
DOUT
MODE
BUSY

ABSOLUTE MAXIMUM RATINGS

+V

to GND ........................................................................ –0.3V to +6V

CC

Analog Inputs to GND ............................................ –0.3V to +V

Digital Inputs to GND ........................................................... –0.3V to +6V

Power Dissipation .......................................................................... 250mW

Maximum Junction Temperature................................................... +150°C

Operating Temperature Range .................................. –40°C to +125°C

Storage Temperature Range .........................................–65°C to +150°C

Lead Temperature (soldering, 10s) ............................................... +300°C

NOTES: (1) Stresses above those listed under “Absolute Maximum Ratings”
may cause permanent damage to the device. Exposure to absolute maximum
conditions for extended periods may affect device reliability. (2) ADS7841ES
0nly. All other grades are: –40°C to +85°C.

(1)

+ 0.3V

CC

ELECTROSTATIC
DISCHARGE SENSITIVITY

This integrated circuit can be damaged by ESD. Texas Instru-

(2)

ments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.

ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published

PACKAGE/ORDERING INFORMATION

MINIMUM MAXIMUM

RELATIVE GAIN SPECIFICATION PACKAGE

ACCURACY ERROR TEMPERATURE PACKAGE DRAWING ORDERING TRANSPORT

PRODUCT (LSB) (LSB) RANGE PACKAGE DESIGNATOR NUMBER NUMBER

ADS7841E ±2 ±4 –40°C to +85°C SSOP-16 DBQ 322 ADS7841E Rails

" " " " " " " ADS7841E/2K5 Tape and Reel
ADS7841P ±2 " –40°C to +85°C DIP-16 N 180 ADS7841P Rails
ADS7841EB ±1 ±3 –40°C to +85°C SSOP-16 DBQ 322 ADS7841EB Rails

" " " " " " " ADS7841EB/2K5 Tape and Reel
ADS7841PB ±1 " –40°C to +85°C DIP-16 N 180 ADS7841PB Rails
ADS7841ES ±2 ±4 –40°C to +125°C SSOP-16 DBQ 322 ADS7841ES/2K5 Tape and Reel

NOTES: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces
of “ADS7841E/2K5” will get a single 2500-piece Tape and Reel.

specifications.

(1)

MEDIA

PIN CONFIGURATIONS

Top View

+V

CH0
CH1
CH2
CH3

COM

SHDN

V

REF

1

CC

2
3
4
5
6
7
8

DIP

ADS7841

SSOP

DCLK

16

CS

15

DIN

14

BUSY

13

DOUT

12

MODE

11

GND

10

+V

9

CC

+V

CH0
CH1
CH2
CH3

COM

SHDN

V

REF

1

CC

2
3
4
5
6
7
8

ADS7841

DCLK

16

CS

15

DIN

14

BUSY

13

DOUT

12

MODE

11

GND

10

+V

9

CC

PIN DESCRIPTIONS

PIN NAME DESCRIPTION

1+VCCPower Supply, 2.7V to 5V
2 CH0 Analog Input Channel 0
3 CH1 Analog Input Channel 1
4 CH2 Analog Input Channel 2
5 CH3 Analog Input Channel 3
6 COM Ground Reference for Analog Inputs. Sets zero code voltage in single-ended mode. Connect this pin to ground or ground reference

7 SHDN Shutdown. When LOW, the device enters a very low power shutdown mode.
8V

9+V
10 GND Ground
11 MODE Conversion Mode. When LOW, the device always performs a 12-bit conversion. When HIGH, the resolution is set by the MODE bit in

12 DOUT Serial Data Output. Data is shifted on the falling edge of DCLK. This output is high impedance when CS is HIGH.
13 BUSY Busy Output. This output is high impedance when CS is HIGH.
14 DIN Serial Data Input. If CS is LOW, data is latched on rising edge of DCLK.
15 CS Chip Select Input. Controls conversion timing and enables the serial input/output register.
16 DCLK External Clock Input. This clock runs the SAR conversion process and synchronizes serial data I/O.

REF

CC

point.

Voltage Reference Input
Power Supply, 2.7V to 5V

the CONTROL byte.

2

ADS7841

SBAS084B

ELECTRICAL CHARACTERISTICS: +5V

At TA = T

PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX MIN TYP MAX UNITS
ANALOG INPUT

Full-Scale Input Span
Absolute Input Range Positive Input –0.2

Capacitance 25 ✻✻pF
Leakage Current 200 200 200 nA

SYSTEM PERFORMANCE

Resolution 12 ✻✻Bits
No Missing Codes 12 12 11 Bits
Integral Linearity Error ±2 ±1 2 LSB
Differential Linearity Error ±0.8 ±0.5 ±1 ±0.8 LSB
Offset Error ±3 ✻✻LSB
Offset Error Match 0.15 1.0 ✻✻ ✻✻LSB
Gain Error ±4 ±3 ±4 LSB
Gain Error Match 0.1 1.0 ✻✻ ✻✻LSB
Noise 30 ✻✻µVrms
Power-Supply Rejection 70 ✻✻dB

SAMPLING DYNAMICS

Conversion Time 12 ✻✻Clk Cycles
Acquisition Time 3 ✻✻Clk Cycles
Throughput Rate 200 ✻✻kHz
Multiplexer Settling Time 500 ✻✻ns
Aperture Delay 30 ✻✻ns
Aperture Jitter 100 ✻✻ps

DYNAMIC CHARACTERISTICS

Total Harmonic Distortion
Signal-to-(Noise + Distortion) V
Spurious-Free Dynamic Range
Channel-to-Channel Isolation V

REFERENCE INPUT

Range 0.1 +V
Resistance DCLK Static 5 ✻✻GΩ
Input Current 40 100 ✻✻ ✻✻µA

DIGITAL INPUT/OUTPUT

Logic Family CMOS ✻✻
Logic Levels

Data Format Straight Binary ✻✻

PWR SUPPLY REQUIREMENTS

+V
Quiescent Current 550 900 ✻✻µA

Power Dissipation 4.5 ✻✻mW

TEMPERATURE RANGE

Specified Performance –40 +85 ✻✻✻+125 °C

to T

MIN

, +VCC = +5V, V

MAX

REF

= +5V, f

= 200kHz, and f

SAMPLE

Positive Input - Negative Input

CLK

= 16 • f

= 3.2MHz, unless otherwise noted.

SAMPLE

ADS7841E, P ADS7841EB, PB

0V

REF

+VCC +0.2

✻✻✻ ✻V
✻✻✻ ✻V

ADS7841ES

Negative Input –0.2 +1.25 ✻✻✻ ✻V

(1)

(2)

VIN = 5Vp-p at 10kHz –78 –72 –80 –76 –78 –72 dB

= 5Vp-p at 10kHz 68 71 70 72 68 71 dB

IN

VIN = 5Vp-p at 10kHz 72 79 76 81 72 79 dB

= 5Vp-p at 50kHz 120 ✻ 120 dB

IN

✻✻✻ ✻V

CC

f

= 12.5kHz 2.5 ✻✻µA

SAMPLE

DCLK Static 0.001 3 ✻✻ ✻✻µA

V

IH

V

IL

V

OH

V

OL

CC

| IIH | ≤ +5µA 3.0 5.5 ✻✻✻ ✻V
| IIL | ≤ +5µA –0.3 +0.8 ✻✻✻ ✻V

IOH = –250µA 3.5 ✻✻ V

IOL = 250µA 0.4 ✻✻V

Specified Performance

f

= 12.5kHz 300 ✻✻µA

SAMPLE

Power-Down Mode

(3)

, CS = +V

4.75 5.25 ✻✻✻ ✻V

CC

3 ✻✻µA

✻ Same specifications as ADS7841E, P.
NOTE: (1) LSB means Least Significant Bit. With V

(PD1 = PD0 = 0) active or SHDN = GND.

ADS7841

SBAS084B

equal to +5.0V, one LSB is 1.22mV. (2) First five harmonics of the test frequency. (3) Auto power-down mode

REF

3

ELECTRICAL CHARACTERISTICS: +2.7V

At TA = –40°C to +85°C, +VCC = +2.7V, V

PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
ANALOG INPUT

Full-Scale Input Span Positive Input - Negative Input 0 V
Absolute Input Range Positive Input –0.2 +V

Capacitance 25 ✻ pF
Leakage Current ±1 ✻ µA

SYSTEM PERFORMANCE

Resolution 12 ✻ Bits
No Missing Codes 12 12 Bits
Integral Linearity Error ±2 ±1 LSB
Differential Linearity Error ±0.8 ±0.5 ±1 LSB
Offset Error ±3 ✻ LSB
Offset Error Match 0.15 1.0 ✻✻LSB
Gain Error ±4 ±3 LSB
Gain Error Match 0.1 1.0 ✻✻ LSB
Noise 30 ✻ µVrms
Power-Supply Rejection 70 ✻ dB

SAMPLING DYNAMICS

Conversion Time 12 ✻ Clk Cycles
Acquisition Time 3 ✻ Clk Cycles
Throughput Rate 125 ✻ kHz
Multiplexer Settling Time 500 ✻ ns
Aperture Delay 30 ✻ ns
Aperture Jitter 100 ✻ ps

DYNAMIC CHARACTERISTICS

Total Harmonic Distortion

(2)

Signal-to-(Noise + Distortion) V
Spurious-Free Dynamic Range V
Channel-to-Channel Isolation V

REFERENCE INPUT

Range 0.1 +V
Resistance DCLK Static 5 ✻ GΩ
Input Current 13 40 ✻✻ µA

DIGITAL INPUT/OUTPUT

Logic Family CMOS ✻
Logic Levels

V

IH

V

IL

V

OH

V

OL

Data Format Straight Binary ✻

POWER SUPPLY REQUIREMENTS

+V

CC

Quiescent Current 280 650 ✻✻ µA

Power Dissipation 1.8 ✻ mW

TEMPERATURE RANGE

Specified Performance –40 +85 ✻✻°C

= +2.5V, f

REF

= 125kHz, and f

SAMPLE

CLK

= 16 • f

= 2MHz, unless otherwise noted.

SAMPLE

ADS7841E, P ADS7841EB, PB

REF

+0.2 ✻✻V

Negative Input –0.2 +0.2 ✻✻V

CC

✻✻V

VIN = 2.5Vp-p at 10kHz –77 –72 –79 –76 dB

= 2.5Vp-p at 10kHz 68 71 70 72 dB

IN

= 2.5Vp-p at 10kHz 72 78 76 80 dB

IN

= 2.5Vp-p at 50kHz 100 ✻ dB

IN

CC

f

= 12.5kHz 2.5 ✻ µA

SAMPLE

DCLK Static 0.001 3 ✻✻ µA

| I

| ≤ +5µA+V

IH

| I

| ≤ +5µA –0.3 +0.8 ✻✻V

IL

IOH = –250µA+V

IOL = 250µA 0.4 ✻ V

• 0.7 5.5 ✻✻V

CC

• 0.8 ✻ V

CC

✻✻V

Specified Performance 2.7 3.6 ✻✻V

f

= 12.5kHz 220 ✻ µA

SAMPLE

Power-Down Mode

(3)

, CS = +V

CC

3 ✻ µA

(1)

✻ Same specifications as ADS7841E, P.
NOTE: (1) LSB means Least Significant Bit. With V

(PD1 = PD0 = 0) active or SHDN = GND.

4

equal to +2.5V, one LSB is 610mV. (2) First five harmonics of the test frequency. (3) Auto power-down mode

REF

ADS7841

SBAS084B

TYPICAL CHARACTERISTICS: +5V

0

–20

–40

–60

–80

–100

–120

FREQUENCY SPECTRUM

(4096 Point FFT; fIN = 10.3kHz, –0.2dB)

0 10025 7550

Frequency (kHz)

Amplitude (dB)

CHANGE IN SIGNAL-TO-(NOISE+DISTORTION)

vs TEMPERATURE

–20–40 100

Temperature (°C)

Delta from +25°C (dB)

0.4

0.2

0.0

–0.2

–0.4

–0.6

0.6

0 20 40 60 80

fIN = 10kHz, –0.2dB

At TA = +25°C, +VCC = +5V, V

(4096 Point FFT; fIN = 1,123Hz, –0.2dB)

0

–20

–40

–60

–80

Amplitude (dB)

–100

–120

0 10025 7550

= +5V, f

REF

FREQUENCY SPECTRUM

Frequency (kHz)

= 200kHz, and f

SAMPLE

CLK

= 16 • f

SAMPLE

= 3.2MHz, unless otherwise noted.

SIGNAL-TO-NOISE RATIO AND SIGNAL-TO-

(NOISE+DISTORTION) vs INPUT FREQUENCY

74

73

72

SINAD

71

70

SNR and SINAD (dB)

69

68

12.0

11.8

11.6

SNR

101 100

Input Frequency (kHz)

EFFECTIVE NUMBER OF BITS

vs INPUT FREQUENCY

85

80

75

SFDR (dB)

70

65

SPURIOUS-FREE DYNAMIC RANGE AND TOTAL
HARMONIC DISTORTION vs INPUT FREQUENCY

–85

SFDR

–80

THD

–75

THD (dB)

–70

–65

101 100

Input Frequency (kHz)

ADS7841

11.4

Effective Number of Bits

11.2

11.0

Input Frequency (kHz)

SBAS084B

101 100

5