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Input
Mux
3rdOrder
DS
Modulator
REFP REFN
PGA
Burnout
Detect
Burnout
Detect
DVDD
DGND
ADS1246
AVSS
AIN0
AIN1
SCLK
DIN
DRDY
DOUT/DRDY
CS
START
RESET
AVDD
InternalOscillator
Adjustable
Digital
Filter
Serial
Interface
and
Control
CLK
Input
Mux
3rdOrder
DS
Modulator
REFP1 REFN1 VREFOUT VREFCOM
REFP0/
GPIO0
REFN0/
GPIO1
Burnout
Detect
Burnout
Detect
DVDD
DGND
IEXC1AVSS
AIN0/IEXC
AIN1/IEXC
AIN2/IEXC/GPIO2
AIN3/IEXC/GPIO3
AIN4/IEXC/GPIO4
AIN5/IEXC/GPIO5
AIN6/IEXC/GPIO6
AIN7/IEXC/GPIO7
ADS1248 Only
SCLK
DIN
DRDY
DOUT/DRDY
CS
START
RESET
AVDD
IEXC2
InternalOscillator
Voltage
Reference
Serial
Interface
and
Control
V
BIAS
GPIO
CLK
ADS1248 Only
ADS1247
ADS1248
PGA
System
Monitor
Adjustable
Digital
Filter
Dual
Current
DACs
VREFMux
ADS1248 Only
V
BIAS
ADS1246
ADS1247
ADS1248
www.ti.com
SBAS426G –AUGUST 2008–REVISED OCTOBER 2011
24-Bit Analog-to-Digital Converters for Temperature Sensors
Check for Samples: ADS1246, ADS1247, ADS1248
1
FEATURES
DESCRIPTION
The ADS1246, ADS1247, and ADS1248 are
23
• 24 Bits, No Missing Codes
highly-integrated, precision, 24-bit analog-to-digital
• Data Output Rates Up to 2kSPS
converters (ADCs). The ADS1246/7/8 feature an
• Single-Cycle Settling for All Data Rates
onboard, low-noise, programmable gain amplifier
(PGA), a precision delta-sigma (ΔΣ) ADC with a
• Simultaneous 50/60Hz Rejection at 20SPS
single-cycle settling digital filter, and an internal
• 4 Differential/7 Single-Ended Inputs (ADS1248)
oscillator. The ADS1247 and ADS1248 also provide a
• 2 Differential/3 Single-Ended Inputs (ADS1247)
built-in, very low drift voltage reference with 10mA
output capacity, and two matched programmable
• Low-Noise PGA: 48nV at PGA = 128
current digital-to-analog converters (DACs). The
• Matched Current Source DACs
ADS1246/7/8 provide a complete front-end solution
• Very Low Drift Internal Voltage Reference:
for temperature sensor applications including thermal
10ppm/°C (max)
couples, thermistors, and RTDs.
• Sensor Burnout Detection
An input multiplexer supports four differential inputs
• 4/8 General-Purpose I/Os (ADS1247/8)
for the ADS1248, two for the ADS1247, and one for
the ADS1246. In addition, the multiplexer has a
• Internal Temperature Sensor
sensor burnout detect, voltage bias for
• Power Supply and V
REF
Monitoring
thermocouples, system monitoring, and
(ADS1247/8)
general-purpose digital I/Os (ADS1247 and
• Self and System Calibration
ADS1248). The onboard, low-noise PGA provides
selectable gains of 1 to 128. The ΔΣ modulator and
• SPI™-Compatible Serial Interface
adjustable digital filter settle in only one cycle, for fast
• Analog Supply Unipolar (+2.7V to
channel cycling when using the input multiplexer, and
+5.25V)/Bipolar (±2.5V) Operation
support data rates up to 2kSPS. For data rates of
• Digital Supply: +2.7V to +5.25V
20SPS or less, both 50Hz and 60Hz interference are
rejected by the filter.
• Operating Temperature –40°C to +125°C
The ADS1246 is offered in a small TSSOP-16
APPLICATIONS
package, the ADS1247 is available in a TSSOP-20
package, and the ADS1248 in a TSSOP-28 package.
• Temperature Measurement
All three devices are rated over the extended
– RTDs, Thermocouples, and Thermistors
specified temperature range of –40°C to +105°C.
• Pressure Measurement
• Industrial Process Control
1
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.
2SPI is a trademark of Motorola, Inc.
3All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Copyright © 2008–2011, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
ADS1246
ADS1247
ADS1248
SBAS426G –AUGUST 2008–REVISED OCTOBER 2011
www.ti.com
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 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
(1)
DUAL SENSOR
EXCITATION CURRENT PACKAGE-
PRODUCT NUMBER OF INPUTS VOLTAGE REFERENCE SOURCES LEAD
1 Differential
ADS1246 or External NO TSSOP-16
1 Single-Ended
2 Differential
ADS1247 or Internal or External YES TSSOP-20
3 Single-Ended
4 Differential
ADS1248 or Internal or External YES TSSOP-28
7 Single-Ended
(1) For the most current package and ordering information, see the Package Option Addendum at the end of this data sheet, or see the TI
website at www.ti.com
ABSOLUTE MAXIMUM RATINGS
(1)
Over operating free-air temperature range (unless otherwise noted).
ADS1246, ADS1247, ADS1248
PARAMETER MIN MAX UNIT
AVDD to AVSS –0.3 +5.5 V
AVSS to DGND –2.8 +0.3 V
DVDD to DGND –0.3 +5.5 V
100, momentary mA
Input current
10, continuous mA
Analog input voltage to AVSS AVSS – 0.3 AVDD + 0.3 V
Digital input voltage to DGND –0.3 DVDD + 0.3 V
Maximum junction temperature +150 °C
Operating temperature range –40 +125 °C
Storage temperature range –60 +150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated is not implied. Exposure to
absolute-maximum-rated conditions for extended periods may affect device reliability.
2 Copyright © 2008–2011, Texas Instruments Incorporated
(V )(Gain)
IN
2
AVSS 0.1V+ +
AVDD 0.1V- -
(V )(Gain)
IN
2
ADS1246
ADS1247
ADS1248
www.ti.com
SBAS426G –AUGUST 2008–REVISED OCTOBER 2011
ELECTRICAL CHARACTERISTICS
Minimum/maximum specifications apply from –40°C to +105°C. Typical specifications are at +25°C. All specifications at
AVDD = +5V, DVDD = +3.3V, AVSS = 0V, V
REF
= +2.048V, and oscillator frequency = 4.096MHz, unless otherwise noted.
ADS1246, ADS1247, ADS1248
PARAMETER CONDITIONS MIN TYP MAX UNIT
ANALOG INPUTS
Full-scale input voltage
±V
REF
/PGA
(1)
V
(V
IN
= ADCINP – ADCINN)
Common-mode input range V
Differential input current 100 pA
Absolute input current See Table 7
PGA gain settings 1, 2, 4, 8, 16, 32, 64, 128
Burnout current source 0.5, 2, or 10 μA
Bias voltage (AVDD + AVSS)/2 V
Bias voltage output impedance 400 Ω
SYSTEM PERFORMANCE
Resolution No missing codes 24 Bits
Data rate 5, 10, 20, 40, 80, 160, 320, 640, 1000, 2000 SPS
Differential input, end point fit, PGA = 1
Integral nonlinearity (INL) 6 15 ppm
V
CM
= 2.5V
Offset error After calibration
(2)
–15 15 μV
Offset drift See Figure 11 to Figure 14 nV/°C
T = +25°C, all PGAs,
Gain error –0.02 ±0.005 0.02 %
data rate = 40, 80, or 160SPS
Gain drift See Figure 19 to Figure 22 ppm/°C
ADC conversion time Single-cycle settling
Noise See Table 1 to Table 4
Normal-mode rejection See Table 9
At dc, PGA = 1 80 90 dB
Common-mode rejection
At dc, PGA = 32 90 125 dB
AVDD/DVDD at dc, PGA = 32,
Power-supply rejection 100 135 dB
data rate = 80SPS
VOLTAGE REFERENCE INPUT
Voltage reference input
0.5 (AVDD – AVSS) – 1 V
(V
REF
= V
REFP
– V
REFN
)
Negative reference input (REFN) AVSS – 0.1 REFP – 0.5 V
Positive reference input (REFP) REFN + 0.5 AVDD + 0.1 V
Reference input current 30 nA
ON-CHIP VOLTAGE REFERENCE
Output voltage 2.038 2.048 2.058 V
Output current
(3)
±10 mA
Load regulation 50 μV/mA
T
A
= +25°C to +105°C 2 10 ppm/°C
Drift
(4)
T
A
= –40°C to +105°C 6 15 ppm/°C
Startup time See Table 10 μs
(1) For V
REF
> 2.7V, the analog input differential voltage should not exceed 2.7V/PGA.
(2) Offset calibration on the order of noise.
(3) Do not exceed this loading on the internal voltage reference.
(4) Specified by the combination of design and final production test.
Copyright © 2008–2011, Texas Instruments Incorporated 3
ADS1246
ADS1247
ADS1248
SBAS426G –AUGUST 2008–REVISED OCTOBER 2011
www.ti.com
ELECTRICAL CHARACTERISTICS (continued)
Minimum/maximum specifications apply from –40°C to +105°C. Typical specifications are at +25°C. All specifications at
AVDD = +5V, DVDD = +3.3V, AVSS = 0V, V
REF
= +2.048V, and oscillator frequency = 4.096MHz, unless otherwise noted.
ADS1246, ADS1247, ADS1248
PARAMETER CONDITIONS MIN TYP MAX UNIT
CURRENT SOURCES (IDACS)
Output current 50, 100, 250, 500, 750, 1000, 1500 μA
Voltage compliance All currents AVDD – 0.7 V
Initial error All currents, each IDAC –6 ±1 6 % of FS
Initial mismatch All currents, between IDACs ±0.15 % of FS
Temperature drift Each IDAC 100 ppm/°C
Temperature drift matching Between IDACs 10 ppm/°C
SYSTEM MONITORS
Voltage T
A
= +25°C 118 mV
Temperature
sensor reading
Drift 405 μV/°C
GENERAL-PURPOSE INPUT/OUTPUT (GPIO)
V
IH
0.7AVDD AVDD V
V
IL
AVSS 0.3AVDD V
Logic levels
V
OH
I
OH
= 1mA 0.8AVDD V
V
OL
I
OL
= 1mA 0.2 AVDD V
DIGITAL INPUT/OUTPUT (other than GPIO)
V
IH
0.7DVDD DVDD V
V
IL
DGND 0.3DVDD V
Logic levels
V
OH
I
OH
= 1mA 0.8DVDD V
V
OL
I
OL
= 1mA DGND 0.2 DVDD V
Input leakage DGND < V
IN
< DVDD ±10 μA
Frequency 1 4.5 MHz
Clock input
(CLK)
Duty cycle 25 75 %
Internal oscillator frequency 3.89 4.096 4.3 MHz
POWER SUPPLY
DVDD 2.7 5.25 V
AVSS –2.5 0 V
AVDD AVSS + 2.7 AVSS + 5.25 V
Normal mode, DVDD = 5V,
230 μA
data rate = 20SPS, internal oscillator
DVDD current Normal mode, DVDD = 3.3V,
210 μA
data rate = 20SPS, internal oscillator
Sleep mode 0.2 µA
Converting, AVDD = 5V,
225 µA
data rate = 20SPS, external reference
Converting, AVDD = 3.3V,
200 µA
data rate = 20SPS, external reference
AVDD current
Sleep mode 0.1 µA
Additional current with internal reference
180 μA
enabled
AVDD = DVDD = 5V,
data rate = 20SPS, internal oscillator, 2.3 mW
external reference
Power dissipation
AVDD = DVDD = 3.3V,
data rate = 20SPS, internal oscillator, 1.4 mW
external reference
TEMPERATURE RANGE
Specified –40 +105 °C
Operating –40 +125 °C
Storage –60 +150 °C
4 Copyright © 2008–2011, Texas Instruments Incorporated
ADS1246
ADS1247
ADS1248
www.ti.com
SBAS426G –AUGUST 2008–REVISED OCTOBER 2011
THERMAL INFORMATION
ADS1246,
ADS1247,
ADS1248
THERMAL METRIC
(1)
UNITS
TSSOP (IPW)
28
θ
JA
Junction-to-ambient thermal resistance
(2)
54.6
θ
JC(top)
Junction-to-case(top) thermal resistance
(3)
11.3
θ
JB
Junction-to-board thermal resistance
(4)
13.0
°C/W
ψ
JT
Junction-to-top characterization parameter
(5)
0.5
ψ
JB
Junction-to-board characterization parameter
(6)
12.7
θ
JC(bottom)
Junction-to-case(bottom) thermal resistance
(7)
n/a
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
(2) The junction-to-ambient thermal resistance under natural convection is obtained in a simulation on a JEDEC-standard, high-K board, as
specified in JESD51-7, in an environment described in JESD51-2a.
(3) The junction-to-case (top) thermal resistance is obtained by simulating a cold plate test on the package top. No specific
JEDEC-standard test exists, but a close description can be found in the ANSI SEMI standard G30-88.
(4) The junction-to-board thermal resistance is obtained by simulating in an environment with a ring cold plate fixture to control the PCB
temperature, as described in JESD51-8.
(5) The junction-to-top characterization parameter, ψ
JT
, estimates the junction temperature of a device in a real system and is extracted
from the simulation data for obtaining θ
JA
, using a procedure described in JESD51-2a (sections 6 and 7).
(6) The junction-to-board characterization parameter, ψ
JB
, estimates the junction temperature of a device in a real system and is extracted
from the simulation data for obtaining θ
JA
, using a procedure described in JESD51-2a (sections 6 and 7).
(7) The junction-to-case (bottom) thermal resistance is obtained by simulating a cold plate test on the exposed (power) pad. No specific
JEDEC standard test exists, but a close description can be found in the ANSI SEMI standard G30-88.
Copyright © 2008–2011, Texas Instruments Incorporated Submit Documentation Feedback 5
Product Folder Link(s): ADS1246 ADS1247 ADS1248
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