TEXAS INSTRUMENTS ADS1253 Technical data

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ADS1253

ADS1253

SBAS199 – MAY 2001

24-Bit, 20kHz, Low Power

ANALOG-TO-DIGITAL CONVERTER

FEATURES

● 24 BITS—NO MISSING CODES

● 19 BITS EFFECTIVE RESOLUTION UP TO

20kHz DATA RATE

● LOW NOISE: 1.8ppm

● FOUR DIFFERENTIAL INPUTS

● INL: 15ppm (max)

● EXTERNAL REFERENCE (0.5V to 5V)

● POWER-DOWN MODE

● SYNC MODE

● LOW POWER: 8mW at 20kHz

5mW at 10kHz

APPLICATIONS

● CARDIAC DIAGNOSTICS

● DIRECT THERMOCOUPLE INTERFACES

● BLOOD ANALYSIS

● INFRARED PYROMETERS

● LIQUID/GAS CHROMATOGRAPHY

● PRECISION PROCESS CONTROL

DESCRIPTION

The ADS1253 is a precision, wide dynamic range, delta­sigma, Analog-to-Digital (A/D) converter with 24-bit reso­lution operating from a single +5V supply. The delta-sigma
architecture is used for wide dynamic range and to guarantee
24 bits of no missing codes performance. An effective
resolution of 19 bits (1.8ppm of rms noise) is achieved for
conversion rates up to 20kHz.

The ADS1253 is designed for high-resolution measurement
applications in cardiac diagnostics, smart transmitters, in­dustrial process control, weight scales, chromatography, and
portable instrumentation. The converter includes a flexible,
two-wire synchronous serial interface for low-cost isolation.

The ADS1253 is a four-channel converter and is offered in
an SSOP-16 package.

ADS1253

CH1+
CH1–
CH2+
CH2–
CH3+
CH3–

CH4+
CH4–

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.

Mux

CHSEL0

CHSEL1

4th-Order

∆Σ

Modulator

www.ti.com

Digital

Filter

V

REF

CLK

Serial

Interface

Control

Copyright © 2001, Texas Instruments Incorporated

SCLK
DOUT/DRDY

+V

DD

GND

ABSOLUTE MAXIMUM RATINGS

Analog Input: Current (Momentary) .............................................. ±100mA

(Continuous) ............................................... ±10mA

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

V

DD

V

Voltage to GND ............................................... –0.3V to VDD + 0.3V

REF

Digital Input Voltage to GND ................................... –0.3V to V

Digital Output Voltage to GND ................................. –0.3V to V

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

Power Dissipation (any package) ................................................. 500mW

Voltage ................................... GND – 0.3V to V

+ 0.3V

DD

+ 0.3V

DD

+ 0.3V

DD

This integrated circuit can be damaged by ESD. Texas Instru­ments 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

ELECTROSTATIC
DISCHARGE SENSITIVITY

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
specifications.

PACKAGE/ORDERING INFORMATION

PACKAGE SPECIFIED

PRODUCT PACKAGE NUMBER RANGE MARKING NUMBER

DRAWING TEMPERATURE PACKAGE ORDERING TRANSPORT

ADS1253E SSOP-16 322 –40°C to +85°C ADS1253E ADS1253E Rails

(1)

MEDIA

"""""ADS1253E/2K5 Tape and Reel

NOTE: (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 “ADS1253E/2K5” will get a single 2500-piece Tape and Reel.

ELECTRICAL CHARACTERISTICS

All specifications at T

PARAMETER CONDITIONS MIN TYP MAX UNITS
ANALOG INPUT

Input Voltage Range GND ±V
Input Impedance CLK = 3,840Hz 260 MΩ

Input Capacitance 6pF
Input Leakage At +25°C550pA

DYNAMIC CHARACTERISTICS

Data Rate 20.8 kHz
Bandwidth –3dB 4.24 kHz
Serial Clock (SCLK) 16 MHz
System Clock Input (CLK) 8 MHz

ACCURACY

Integral Non-Linearity
THD 1kHz Input; 0.1dB below FS 105 dB
Noise 1.8 2.7 ppm of FSR, rms
Resolution 24 Bits
No Missing Codes 24 Bits
Common-Mode Rejection 60Hz, AC 90 102 dB
Gain Error 0.1 1 % of FSR
Offset Error ±20 ±100 ppm of FSR
Gain Sensitivity to V
Power-Supply Rejection Ratio 70 88 dB

PERFORMANCE OVER TEMPERATURE

Offset Drift 0.07 ppm/°C
Gain Drift 0.4 ppm/°C

VOLTAGE REFERENCE

V

REF

Load Current 32 µA

NOTE: (1) Applies to full-differential signals.

MIN

REF

to T

, VDD = +5V, CLK = 8MHz, and V

MAX

(1)

= 4.096, unless otherwise specified.

REF

ADS1253E

REF

CLK = 1MHz 1 MΩ
CLK = 8MHz 125 kΩ

At T

MIN

to T

MAX

±0.0002 ±0.0015 % of FSR

1:1

0.5 4.096 V

1nA

DD

V

V

2

ADS1253

SBAS199

ELECTRICAL CHARACTERISTICS (Cont.)

All specifications at T

PARAMETER CONDITIONS MIN TYP MAX UNITS

DIGITAL INPUT/OUTPUT

Logic Family CMOS
Logic Level: V

V
V

V
Input (SCLK, CLK, CHSEL0, CHSEL1) Hysteresis 0.6 V
Data Format

POWER-SUPPLY REQUIREMENTS

Operation +4.75 +5 +5.25 VDC
Quiescent Current 1.5 2 mA
Operating Power 7.5 10 mW
Power-Down Current 0.4 1 µA

TEMPERATURE RANGE

Operating –40 +85 °C
Storage –60 +100 °C

to T

MIN

IH
IL
OH
OL

, VDD = +5V, CLK = 8MHz, and V

MAX

= 4.096, unless otherwise specified.

REF

ADS1253E

+4.0 +VDD + 0.3 V

IOH = –500µA +4.5 V

IOL = 500µA0.4V

–0.3 +0.8 V

Offset Binary Two’s Complement

PIN CONFIGURATION

Top View SSOP-16

CH1+

CH1–

CH2+

CH2–

CH3+

CH3–

+V

CLK

1

2

3

4

5

6

7

DD

8

ADS1253E

CH4+

16

15

CH4–

V

14

13

GND

CHSEL0

12

11

CHSEL1

SCLK

10

9

DOUT/DRDY

REF

PIN DESCRIPTIONS

PIN NAME PIN DESCRIPTION

1 CH1+ Analog Input: Positive Input of the Differen-

2 CH1– Analog Input: Negative Input of the Differ-

3 CH2+ Analog Input: Positive Input of the Differen-

4 CH2– Analog Input: Negative Input of the Differ-

5 CH3+ Analog Input: Positive Input of the Differen-

6 CH3– Analog Input: Negative Input of the Differ-

7+V
8 CLK Digital Input: Device System Clock. The

9 DOUT/DRDY Digital Output: Serial Data Output/Data

10 SCLK Digital Input: Serial Clock. The serial clock

11 CHSEL1 Digital Input: Used to select analog input

12 CHSEL0 Digital Input: Used to select analog input

13 GND Input: Ground.
14 V

15 CH4– Analog Input: Negative Input of the Differ-

16 CH4+ Analog Input: Positive Input of the Differen-

DD

REF

tial Analog Input.

ential Analog Input.

tial Analog Input.

ential Analog Input.

tial Analog Input.

ential Analog Input.
Input: Power Supply Voltage, +5V.

system clock is in the form of a CMOS­compatible clock. This is a Schmitt-Trigger
input.

Ready. This output indicates that a new
output word is available from the ADS1253
data output register. The serial data is
clocked out of the serial data output shift
register using SCLK.

is in the form of a CMOS-compatible clock.
The serial clock operates independently
from the system clock, therefore, it is pos­sible to run SCLK at a higher frequency
than CLK. The normal state of SCLK is
LOW. Holding SCLK HIGH will either ini­tiate a modulator reset for synchronizing
multiple converters or enter power-down
mode. This is a Schmitt-Trigger input.

channel. This is a Schmitt-Trigger input.

channel. This is a Schmitt-Trigger input.

Analog Input: Reference Voltage Input.

ential Analog Input.

tial Analog Input.

ADS1253

SBAS199

3

TYPICAL CHARACTERISTICS

At TA = +25°C, VDD = +5V, CLK = 8MHz, and V

= 4.096, unless otherwise specified.

REF

2.0

RMS NOISE vs DATA OUTPUT RATE

1.8

1.6

1.4

RMS Noise (ppm of FS)

1.2

1.0
100 1k 10k 100k

Data Output Rate (Hz)

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

RMS Noise (ppm of FS)

0.4

0.2

0.0
–40 –20 0 20 40 60 80 100

RMS NOISE vs TEMPERATURE

Temperature (°C)

20.0

EFFECTIVE RESOLUTION vs DATA OUTPUT RATE

19.8

19.6

19.4

19.2

19.0

18.8

18.6

18.4

Effective Resolution (Bits)

18.2

18.0
1k100 10k 100k

Data Output Rate (Hz)

EFFECTIVE RESOLUTION vs TEMPERATURE

20.0

19.8

19.6

19.4

19.2

19.0

18.8

18.6

18.4

Effective Resolution (Bits)

18.2

18.0
–40 –20 0 20 40 60 80 100

Temperature (°C)

18

RMS NOISE vs V

16
14
12
10

8
6

RMS Noise (µV)

4
2
0

0.50.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
V

REF

4

VOLTAGE

REF

Voltage (V)

14

RMS NOISE vs V

VOLTAGE

REF

12

10

8

6

4

RMS Noise (ppm of FS)

2

0

0.0 1.0 1.50.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
V

(V)

REF

ADS1253

SBAS199

TYPICAL CHARACTERISTICS (Cont.)

OFFSET vs TEMPERATURE

20
18
16
14
12
10

8
6
4
2
0

DC Offset (ppm of FS)

–40 –20 0 20 40 60 80 100

Temperature (°C)

At TA = +25°C, VDD = +5V, CLK = 8MHz, and V

= 4.096, unless otherwise specified.

REF

2.0

1.8

1.6

1.4

RMS Noise (ppm of FS)

1.2

1.0

5

4

3

RMS NOISE vs INPUT VOLTAGE (V

–5 –4 –3 –2 –1 0 1 2 3 4 5

Input Voltage (V)

INTEGRAL NON-LINEARITY vs DATA OUTPUT RATE

REF

= 5.0V)

INTEGRAL NON-LINEARITY vs TEMPERATURE

5

4

3

2

INL (ppm of FS)

1

0

–40 –20 0 20 40 60 80 100

Temperature (°C)

2

INL (ppm of FS)

1

0

100 1k 10k 100k

Data Output Rate (Hz)

570

560

550

540

530

520

Gain Error (ppm of FS)

510

500

–40 –20 0 20 40 60 80 100

ADS1253

SBAS199

GAIN ERROR vs TEMPERATURE

Temperature (°C)

0

–20

–40

–60

PSRR (dB)

–80

–100

–120

02468

PSRR vs CLK FREQUENCY

Clock Frequency (MHz)

5

TYPICAL CHARACTERISTICS (Cont.)

At TA = +25°C, VDD = +5V, CLK = 8MHz, and V

= 4.096, unless otherwise specified.

REF

–60
–65
–70
–75
–80
–85
–90
–95

CMR at 60Hz (dB)

–100
–105

–110

012345678

1.64

1.62

1.60

1.58

1.56

1.54

Current (mA)

1.52

1.50

1.48

1.46
–40 –20 0 20 40 60 80 100

CMR AT 60Hz vs CLK FREQUENCY

Clock Frequency (MHz)

CURRENT vs TEMPERATURE

Temperature (°C)

a0873473

nn

–70

–75

–80

–85

–90

CMR (dB)

–95

–100

–105

10 100 1k 10k 100k

9
8
7
6
5
4
3
2

Power Dissipation (mW)

1
0

POWER DISSIPATION vs CLK FREQUENCY

012345 768

CMR vs FREQUENCY

Common-Mode Signal Frequency (Hz)

Clock Frequency (MHz)

V

CURRENT vs CLK FREQUENCY

35

30

25

20

15

Current (µA)

REF

V

10

5

0

0123456789

REF

Clock Frequency (MHz)

0
–20
–40
–60
–80

–100
–120

Relative Magnitude (dB)

–140
–160

01234567891011

(1kHz input at 0.1dB less than full-scale)

6

TYPICAL FFT

Input Signal Frequency (kHz)

ADS1253

SBAS199