ADS1246| Datasheet

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ADS1246 ADS1247 ADS1248

www.ti.com ................................................................................................................................................................................................ SBAS426 AUGUST 2008

24-Bit Analog-to-Digital Converters for Temperature Sensors
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FEATURES
24 Bits, No Missing Codes Data Output Rates Up to 2kSPS Single-Cycle Settling for All Data Rates Simultaneous 50/60Hz Rejection at 20SPS 4 Differential/7 Signal-Ended Inputs (ADS1248) 2 Differential/3 Single-Ended Inputs (ADS1247) Low-Noise PGA: 48nV at PGA = 128 Matched Current Source DACs Very Low Drift Internal Voltage Reference: 10ppm/ C (max) with 10mA Output Capacity Sensor Burnout Detection 4/8 General-Purpose I/Os (ADS1247/48) Internal Temperature Sensor Power Supply and VREF Monitoring Self and System Calibration SPITM-Compatible Serial Interface Unipolar (+3V to +5V)/Bipolar( 2.5V) Operation Digital Supply: +2.7V to +5.25V Operating Temperature 40 C to +125 C

DESCRIPTION
The ADS1246, ADS1247, and ADS1248 are highly-integrated, precision, 24-bit analog-to-digital converters (ADCs). The ADS1246/7/8 feature an onboard, low-noise, programmable gain amplifier (PGA), a precision delta-sigma ADC with a single-cycle settling digital filter, and an internal oscillator. The ADS1247 and ADS1248 also provide a built-in, very low drift voltage reference with 10mA output capacity, and two matched programmable current digital-to-analog converters (DACs). The ADS1246/7/8 provide a complete front-end solution for temperature/bridge sensor applications including thermal couples, thermistors, RTDs, and strain-gauge applications.

APPLICATIONS
Temperature Measurement RTDs, Thermocouples, and Thermistors Weigh Scales and Bridge Sensors Pressure Measurement Industrial Process Control

The ADS1246 is offered in a small TSSOP-16 package, the ADS1247 is available in a TSSOP-20 package, and the ADS1248 in a TSSOP-28 package. All three devices are specified over the extended temperature range of 40 C to +105 C.
AVDD Burnout Detect VBIAS VREF Mux GPIO REFP0/ REFN0/ ADS1248 Only GPIO0 GPIO1 REFP1 REFN1 VREFOUT VREFCOM DVDD

AVDD Burnout Detect

REFP

REFN

DVDD

ADS1246
System Monitor Serial Interface and Control SCLK DIN 3rd Order DS Modulator DRDY DOUT/DRDY CS START VBIAS Internal Oscillator/ External Clock RESET AIN0/IEXC AIN1/IEXC AIN2/IEXC/GPIO2 AIN3/IEXC/GPIO3 AIN4/IEXC/GPIO4 AIN5/IEXC/GPIO5 AIN6/IEXC/GPIO6 AIN7/IEXC/GPIO7 ADS1248 Only

Voltage Reference

ADS1247 ADS1248
SCLK DIN

System Monitor Input Mux PGA 3rd Order DS Modulator Dual Current DACs Burnout Detect Programmable Digital Filter Serial Interface and Control

AIN0 AIN1

Input Mux

PGA

Programmable Digital Filter

DRDY DOUT/DRDY CS START RESET

Burnout Detect

Internal Oscillator/ External Clock

AVSS

CLK

DGND

AVSS

IEXC1 IEXC2 ADS1248 Only

CLK

DGND

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. SPI is a trademark of Motorola, Inc. All other trademarks are the property of their respective owners.
Copyright 2008, Texas Instruments Incorporated

PRODUCT PREVIEW information concerns products in the formative or design phase of development. Characteristic data and other specifications are design goals. Texas Instruments reserves the right to change or discontinue these products without notice.

PRODUCT PREVIEW

An input multiplexer supports four differential inputs for the ADS1248, two for the ADS1247, and one for the ADS1246. In addition, the multiplexer has a sensor burnout detect, voltage bias for thermocouples, system monitoring, and general-purpose digital I/Os (ADS1247 and ADS1248). The onboard, low-noise PGA provides selectable gains of 1 to 128. The delta-sigma modulator and programmable digital filter settle in only one cycle, for fast channel cycling when using the input multiplexer, and support data rates up to 2kSPS. For data rates of 20SPS or less, both 50Hz and 60Hz interference are effectively rejected by the filter.