Burr Brown Products from Texas Instruments
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AD S12
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ADS1225 ADS1226
SBAS346 – MAY 2006
24-Bit Analog-to-Digital Converter with One- and Two-Channel Differential Inputs and Internal Oscillator
FEATURES
• • • • • • • • • • • • • • • • • 100SPS Data Rate (High-Speed Mode) Single-Cycle Settling Easy Conversion Control with START Pin Automatic Shutdown Low Noise: 4µVRMS Noise (High-Resolution Mode) Input Multiplexer with Two Differential Channels (ADS1226) Voltage Reference Supports Ratiometric Measurements Self-Calibrating Simple Read-Only 2-Wire Serial Interface Internal High-Impedance Input Buffer Internal Temperature Sensor Internal Oscillator Low-Power: 1mW While Operating, < 1µA During Shutdown Analog and Digital Supplies: 2.7V to 5.5V
DESCRIPTION
The ADS1225 and ADS1226 are 24-bit delta-sigma analog-to-digital (A/D) converters. They offer excellent performance, ease-of-use, and low power in a small 4mm × 4mm QFN package and are well-suited for demanding high-resolution measurements, especially in portable and other space-saving and power-constrained applications. The ADS1225 and ADS1226 convert on command using a dedicated START pin. Simply pulse this pin to initiate a conversion. Data is read in a single cycle for retrieval over a 2-wire serial interface that easily connects to popular microcontrollers like the MSP430. After the conversion completes, the ADS1225 and ADS1226 automatically shuts down all circuitry. Internal features include a two-channel multiplexer (ADS1226), selectable input buffer, temperature sensor, and oscillator. The full-scale range is defined by the external voltage reference with support provided for up to a 5V differential input signal. Two operating modes allow for speed (100SPS data rate, 15µVRMS noise) or resolution (4µVRMS noise, 16SPS data rate). The ADS1225/6 supports 2.7 to 5.5V analog and digital supplies. Power consumption is 1mW while converting with 3V supplies. The ADS1225 and ADS1226 are fully specified over an extended industrial temperature range of –40°C to +105°C.
TEMPEN AVDD VREFP VREFN DVDD START AINP1 AINN1 AINP2 AINN2 Oscillator MODE MUX Buffer DS ADC Serial Interface SCLK DRDY/DOUT
APPLICATIONS
Hand-Held Instrumentation Portable Medical Equipment Industrial Process Control
MUX ADS1226 Only
BUFEN
GND
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. All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.
Copyright © 2006, Texas Instruments Incorporated
ADS1225 ADS1226
www.ti.com
SBAS346 – MAY 2006
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.
ORDERING INFORMATION
For the most current package and ordering information, see the Package Option Addendum located at the end of this data sheet or see the TI web site at www.ti.com.
ABSOLUTE MAXIMUM RATINGS
Over operating free-air temperature range (unless otherwise noted) (1)
ADS1225, ADS1226 AVDD to GND DVDD to GND Input current Analog input voltage to GND Digital input voltage to GND Maximum junction temperature Operating temperature range Storage temperature range (1) –0.3 to +6 –0.3 to +6 100, momentary 10, continuous –0.3 to AVDD +0.3 –0.3 to to AVDD +0.3 +150 –55 to +125 –50 to +150 UNIT V V mA mA V V °C °C °C
Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied.
2
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ADS1225 ADS1226
www.ti.com
SBAS346 – MAY 2006
ELECTRICAL CHARACTERISTICS
All specifications at TA = –40°C to +105°C, AVDD = +5V, DVDD = +3V, and VREF = +5V, unless otherwise noted.
ADS1225, ADS1226 PARAMETER Analog Input Full-scale input voltage Absolute input voltage AINP – AINN Buffer off; AINP, AINN with respect to GND Buffer on; AINP, AINN with respect to GND Buffer off Buffer on Buffer off GND – 0.1 GND + 0.05 2 1 4 ±VREF AVDD + 0.1 AVDD – 1.5 V V V MΩ GΩ MΩ Bits 100 16 0.0005 60 0.3 0.004 0.3 At DC At DC, ± 10% ∆ in AVDD At DC, DVDD = 2.7V to 5.5V High-Speed mode Noise High-Resolution mode Temperature Sensor Temperature sensor voltage Temperature sensor coefficient Voltage Reference Input Reference input voltage Negative reference input Positive reference input Voltage reference impedance VREF = VREFP – VREFN 0.5 GND - 0.1 VREFN + 0.5 1.5 5 AVDD VREFP – 0.5 AVDD + 0.1 V V V MΩ TA = +25°C 106 360 mV µV/°C 0.4 85 95 95 80 1.5 0.025 125 22 0.0020 200 SPS (1) SPS (1) % of FSR (2) µV µV/°C % ppm/°C dB dB dB ppm of FSR, rms ppm of FSR, rms TEST CONDITIONS MIN TYP MAX UNIT
Differential input impedance Common-mode input impedance System Performance Resolution Data rate Integral nonlinearity (INL) Offset error Offset error drift Gain error Gain error drift Common-mode rejection Analog power-supply rejection Digital power-supply rejection
24 High-Speed mode High-Resolution mode End-point fit 75 12
(1) (2)
SPS = samples per second. FSR = full-scale range = 2 × VREF.
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ADS1225 ADS1226
www.ti.com
SBAS346 – MAY 2006
ELECTRICAL CHARACTERISTICS (continued)
All specifications at TA = –40°C to +105°C, AVDD = +5V, DVDD = +3V, and VREF = +5V, unless otherwise noted.
ADS1225, ADS1226 PARAMETER Digital Input/Output VIH Logic levels VIL VOH VOL Input leakage Power Supply AVDD DVDD Shutdown AVDD = 5V, converting, buffer off AVDD current AVDD = 5V, converting, buffer on AVDD = 3V, converting, buffer off AVDD = 3V, converting, buffer on Shutdown DVDD current DVDD = 5V, converting DVDD = 3V, converting Total power dissipation Temperature Range Specified Operating Storage –40 –55 –60 +105 +125 +150 °C °C °C AVDD = 5V, DVDD = 3V, buffer off AVDD = DVDD = 3V, buffer off 2.7 2.7