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Электронный компонент: ADS1244IDGST

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ADS1244
SBAS273 DECEMBER 2002
www.ti.com
DESCRIPTION
The ADS1244 is a 24-bit, delta-sigma Analog-to-Digital (A/D)
converter. It offers excellent performance and very low power
in an MSOP-10 package and is well suited for demanding
high-resolution measurements, especially in portable and
other space- and power-constrained systems.
A 3rd-order delta-sigma modulator and digital filter form the
basis of the A/D converter. The analog modulator has a
5V
differential input range. The digital filter rejects both 50Hz
and 60Hz signals, completely settles in one cycle, and
outputs data at 15 samples per second.
A simple, 2-wire serial interface provides all the necessary
control. Data retrieval, self-calibration, and Sleep Mode are
handled with a few simple waveforms. When only single
conversions are needed, the ADS1244 can be shut down
(Sleep Mode) while idle between measurements to dramati-
cally reduce the overall power dissipation. Multiple ADS1244s
can be connected together to create a synchronously sam-
pling multichannel measurement system. The ADS1244 is
designed to easily connect to microcontrollers, such as the
MSP430.
The ADS1244 supports 2.5V to 5.25V analog supplies and
1.8V to 3.6V digital supplies. Power is typically less than
270
W in normal operation and less than 1
W during Sleep
Mode.
FEATURES
q
20-BIT EFFECTIVE RESOLUTION
q
CURRENT CONSUMPTION: 90
A
q
ANALOG SUPPLY: 2.5V to 5.25V
q
DIGITAL SUPPLY: 1.8V to 3.6V
q
5V DIFFERENTIAL INPUT RANGE
q
0.0002% INL (TYP), 0.0008% INL (MAX)
q
SIMPLE 2-WIRE SERIAL INTERFACE
q
SIMULTANEOUS 50Hz AND 60Hz REJECTION
q
SINGLE CONVERSIONS WITH SLEEP MODE
q
SINGLE-CYCLE SETTLING
q
SELF-CALIBRATION
q
WELL-SUITED FOR MULTICHANNEL SYSTEMS
q
EASILY CONNECTS TO THE MSP430
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.
Copyright 2002, Texas Instruments Incorporated
Low-Power, 24-Bit
ANALOG-TO-DIGITAL CONVERTER
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.
APPLICATIONS
q
HAND-HELD INSTRUMENTATION
q
PORTABLE MEDICAL EQUIPMENT
q
INDUSTRIAL PROCESS CONTROL
q
WEIGH SCALES
Digital
Filter
Serial
Interface
DRDY/DOUT
SCLK
CLK
AINN
AINP
VREFP VREFN
AVDD
GND
DVDD
3rd-Order
Modulator
ADS1
244
ADS1244
2
SBAS273
www.ti.com
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Texas Instru-
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 degrada-
tion 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.
ABSOLUTE MAXIMUM RATINGS
(1)
AVDD
to GND ....................................................................... 0.3V to +6V
DVDD to GND ................................................................... 0.3V to +3.6V
Input Current ............................................................... 100mA, Momentary
Input Current ................................................................ 10mA, Continuous
Analog Input Voltage to GND .............................. 0.5V to AVDD + 0.5V
Digital Input Voltage to GND ............................... 0.3V to DVDD + 0.3V
Digital Output Voltage to GND ............................. 0.3V to DVDD + 0.3V
Maximum Junction Temperature ................................................... +150
C
Operating Temperature Range ........................................ 40
C to +85
C
Storage Temperature Range ......................................... 60
C to +150
C
Lead Temperature (soldering, 10s) ............................................... +300
C
NOTE: (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.
SPECIFIED
PACKAGE
TEMPERATURE
PACKAGE
ORDERING
TRANSPORT
PRODUCT
PACKAGE-LEAD
DESIGNATOR
(1)
RANGE
MARKING
NUMBER
MEDIA, QUANTITY
ADS1244
MSOP-10
DGS
40
C to +85
C
BHG
ADS1244IDGST
Tape and Reel, 250
"
"
"
"
"
ADS1244IDGSR
Tape and Reel, 2500
NOTE: (1) For the most current specifications and package information, refer to our web site at www.ti.com.
PACKAGE/ORDERING INFORMATION
PIN CONFIGURATION
PIN
NUMBER
NAME
DESCRIPTION
1
GND
Analog and Digital Ground
2
VREFP
Positive Reference Input
3
VREFN
Negative Reference Input
4
AINN
Negative Analog Input
5
AINP
Positive Analog Input
6
AVDD
Analog Power Supply, 2.5V to 5.25V
7
DVDD
Digital Power Supply, 1.8V to 3.6V
8
DRDY/
Dual-Purpose Output:
DOUT
Data Ready: Indicates valid data by going LOW.
Data Output: Outputs data, MSB first, on the first
rising edge of SCLK.
9
SCLK
Serial Clock Input: Clocks out data on the rising
edge. Used to initiate calibration and Sleep Mode,
see text for more details.
10
CLK
System Clock Input: Typically 2.4576MHz
PIN DESCRIPTIONS
Top View
MSOP
1
2
3
4
5
10
9
8
7
6
CLK
SCLK
DRDY/DOUT
DVDD
AVDD
GND
VREFP
VREFN
AINN
AINP
ADS1244
PRODUCT
DESCRIPTION
ADS1244-EVM
ADS1244 Evaluation Module
DEMO BOARD ORDERING INFORMATION
ADS1244
3
SBAS273
www.ti.com
ELECTRICAL CHARACTERISTICS
All specifications 40
C to +85
C, AVDD = 5V, DVDD = +3V, f
CLK
= 2.4576MHz, and V
REF
= 2.5V, unless otherwise specified.
ADS1244
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
ANALOG INPUT
Full-Scale Input Voltage Range
AINP AINN
2V
REF
V
Absolute Input Range
AINP, AINN with Respect to GND
GND 0.1
AVDD + 0.1
V
Differential Input Impedance
f
CLK
= 2.4576MHz
5
M
SYSTEM PERFORMANCE
Resolution
No Missing Codes
24
Bits
Data Rate
f
CLK
= 2.4576MHz
15
sps
(1)
Integral Nonlinearity (INL)
Differential Input Signal, End Point Fit
0.0002
0.0008
% FSR
(2)
Offset Error
1
10
ppm of FSR
Offset Error Drift
(3)
0.01
ppm of FSR/
C
Gain Error
0.005
0.02
%
Gain Error Drift
(3)
0.5
ppm/
C
Common-Mode Rejection
at DC
90
130
dB
f
CM
(4)
= 50
1Hz, f
CLK
= 2.4576MHz
100
dB
f
CM
= 60
1Hz, f
CLK
= 2.4576MHz
100
dB
Normal-Mode Rejection
f
SIG
(5)
= 50
1Hz, f
CLK
= 2.4576MHz
60
dB
f
SIG
= 60
1Hz, f
CLK
= 2.4576MHz
70
dB
Input Referred Noise
1
ppm of FSR, rms
Analog Power-Supply Rejection
at DC,
AVDD = 5%
105
dB
Digital Power-Supply Rejection
at DC,
DVDD = 5%
100
dB
VOLTAGE REFERENCE INPUT
Reference Input Voltage (V
REF
)
V
REF
VREFP VREFN
0.5
2.5
AVDD
(6)
V
Negative Reference Input (VREFN)
GND 0.1
VREFP 0.5
V
Positive Reference Input (VREFP)
VREFN + 0.5
AVDD + 0.1
V
Voltage Reference Impedance
f
CLK
= 2.4576MHz
1
M
DIGITAL INPUT/OUTPUT
Logic Levels
V
IH
(CLK, SCLK)
2.1
5.25
V
V
IL
(CLK, SCLK)
GND
0.9
V
V
OH
(DRDY/DOUT )
I
OH
= 1mA
2.6
V
V
OL
(DRDY/DOUT )
I
OL
= 1mA
0.4
V
Input Leakage (CLK, SCLK)
0 < (CLK, SCLK) < DVDD
10
A
CLK Frequency (f
CLK
)
6
MHz
CLK Duty Cycle
30
70
%
POWER SUPPLY
AVDD
2.5
5.25
V
DVDD
1.8
3.6
V
AVDD Current
Sleep Mode
0.1
1
A
AVDD = 3V
85
A
AVDD = 5V
90
150
A
DVDD Current
Sleep Mode, CLK Stopped
0.1
A
Sleep Mode, 2.4576MHz CLK Running
1.3
5
A
DVDD = 3V
4.5
10
A
Total Power Dissipation
AVDD = DVDD = 3V
270
W
NOTES: (1) sps = Samples Per Second. (2) FSR = Full-Scale Range = 4V
REF
. (3) Recalibration can reduce these errors to the level of the noise. (4) f
CM
is the frequency
of the common-mode input. (5) f
SIG
is the frequency of the input signal. (6) It will not be possible to reach the digital output full-scale code when V
REF
> AVDD/2.
ADS1244
4
SBAS273
www.ti.com
TYPICAL CHARACTERISTICS
At T
A
= +25
C, AVDD = +5V, DVDD = +3V, f
CLK
= 2.4576MHz, and V
REF
=
+2.5V, unless otherwise specified.
ANALOG CURRENT vs TEMPERATURE
Temperature (
C)
Current (
A)
15
5
25
35
55
75
95
45
110
105
100
95
90
85
80
75
70
AVDD = 5V, f
CLK
= 4.9152MHz
AVDD = 3V, f
CLK
= 2.4576MHz
DIGITAL CURRENT vs TEMPERATURE
Temperature (
C)
Current (
A)
15
5
25
35
55
75
95
45
12
10
8
6
4
2
0
DVDD = 1.8V, f
CLK
= 2.4576MHz
DVDD = 3V, f
CLK
= 4.9152MHz
ANALOG CURRENT vs ANALOG SUPPLY
Analog Supply (V)
Current (
A)
3
3.5
4
4.5
5
5.5
2.5
94
92
90
88
86
84
82
80
f
CLK
= 4.9152MHz
f
CLK
= 2.4576MHz
DIGITAL CURRENT vs DIGITAL SUPPLY
Digital Supply (V)
Current (
A)
2
2.5
3
3.5
4
1.5
20
18
16
14
12
10
8
6
4
2
0
f
CLK
= 4.9152MHz
f
CLK
= 2.4576MHz
INTEGRAL NONLINEARITY vs V
IN
V
IN
(V)
INL
(ppm of FSR)
1
1
3
3
5
5
3
2
1
0
1
2
3
T = 40
C
T = 25
C
AVDD = 5V, V
REF
= 2.5V
T = 85
C
INTEGRAL NONLINEARITY vs V
IN
V
IN
(V)
INL
(ppm of FSR)
0.5
0.5
1.5
1.5
2.5
2.5
3
2
1
0
1
2
3
T = 25
C
T = 85
C
T = 40
C
AVDD = 3V, V
REF
= 1.25V
ADS1244
5
SBAS273
www.ti.com
TYPICAL CHARACTERISTICS
(Cont.)
At T
A
= +25
C, AVDD = +5V, DVDD = +3V, f
CLK
= 2.4576MHz, and V
REF
=
+2.5V, unless otherwise specified.
INTEGRAL NONLINEARITY vs ANALOG SUPPLY
Analog Supply (V)
INL
(ppm of FSR)
1.5
2
2.5
3
3.5
4
4.5
5
5.5
20
18
16
14
12
10
8
6
4
2
0
T = 25
C
T = 85
C
T = 40
C
V
REF
= AVDD
INTEGRAL NONLINEARITY vs ANALOG SUPPLY
Analog Supply (V)
INL
(ppm of FSR)
1.5
2
2.5
3
3.5
4
4.5
5
5.5
20
18
16
14
12
10
8
6
4
2
0
T = 25
C
T = 85
C
T = 40
C
V
REF
= AVDD/2
OFFSET vs TEMPERATURE
Temperature (
C)
Normalized Of
fset (ppm of FSR)
15
5
25
35
55
75
95
45
1
0.5
0
0.5
1
GAIN vs TEMPERATURE
Temperature (
C)
Normalized Gain
15
5
25
35
55
75
95
45
1.00008
1.00006
1.00004
1.00002
1
0.99998
0.99996
0.99994
0.99992
0.9999
NOISE vs TEMPERATURE
Temperature (
C)
Noise (ppm of FSR, rms)
25
5
15
35
55
75
95
45
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
NOISE vs INPUT SIGNAL
V
IN
(V)
Noise (ppm of FSR, rms)
3
1
1
3
5
5
1.6
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6