ADS1232                                                                                                                   ...
ADS1232ADS1234                                                                                                            ...
ADS1232                                                                                                                   ...
ADS1232ADS1234                                                                                                            ...
ADS1232                                                                                                                   ...
ADS1232ADS1234                                                                                                            ...
ADS1232                                                                                                                   ...
ADS1232ADS1234                                                                                                            ...
ADS1232                                                                                                                   ...
ADS1232ADS1234                                                                                                            ...
ADS1232                                                                                                                   ...
ADS1232ADS1234                                                                                                            ...
ADS1232                                                                                                                   ...
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
24 bit analog-to-digital converter for bridge sensors
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24 bit analog-to-digital converter for bridge sensors

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24 bit analog-to-digital converter for bridge sensors

  1. 1. ADS1232 ADS1234 www.ti.com SBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 24-Bit Analog-to-Digital Converter For Bridge Sensors1FEATURES DESCRIPTION•2 Complete Front-End for Bridge Sensors The ADS1232 and ADS1234 are precision 24-bit• Up to 23.5 Effective Bits analog-to-digital converters (ADCs). With an onboard,• Onboard, Low-Noise PGA low-noise programmable gain amplifier (PGA), precision delta-sigma ADC and internal oscillator, the• RMS Noise: ADS1232/4 provide a complete front-end solution for 17nV at 10SPS (PGA = 128) bridge sensor applications including weigh scales, 44nV at 80SPS (PGA = 128) strain gauges and pressure sensors.• 19.2-Bit Noise-Free Resolution at Gain = 64 The input multiplexer accepts either two (ADS1232)• Over 100dB Simultaneous 50Hz and 60Hz or four (ADS1234) differential inputs. The ADS1232 Rejection also includes an onboard temperature sensor to• Flexible Clocking: monitor ambient temperature. The onboard, low-noise Low-Drift Onboard Oscillator (±3%) PGA has a selectable gain of 1, 2, 64, or 128 supporting a full-scale differential input of ±2.5V, Optional External Crystal ±1.25V, ±39mV, or ±19.5mV. The delta-sigma ADC• Selectable Gains of 1, 2, 64, and 128 has 23.5-bit effective resolution and is comprised of a• Easy Ratiometric Measurements– 3rd-order modulator and 4th-order digital filter. Two External Voltage Reference up to 5V data rates are supported: 10SPS (with both 50Hz and 60Hz rejection) and 80SPS. The ADS1232/4 can be• Selectable 10SPS or 80SPS Data Rates clocked externally using an oscillator or a crystal.• Two-Channel Differential Input with Built-In There is also an internal oscillator available that Temperature Sensor (ADS1232) requires no external components. Offset calibration is• Four-Channel Differential Input (ADS1234) performed on-demand and the ADS1232/4 can be put in a low-power standby mode or shut off• Simple Serial Digital Interface completely in power-down mode. All of the features of• Supply Range: 2.7V to 5.3V the ADS1232/4 are operated through simple• –40°C to +105°C Temperature Range pin-driven control. There are no digital registers to program in order to simplify software development.APPLICATIONS Data are output over an easily-isolated serial interface that connects directly to the MSP430 and• Weigh Scales other microcontrollers.• Strain Gauges The ADS1232 is available in a TSSOP-24 package• Pressure Sensors and the ADS1234 is in a TSSOP-28. Both are fully• Industrial Process Control specified from -40°C to +105°C. AVDD CAP REFP REFN DVDD Gain = GAIN [1:0] AINP1 1, 2, 64, or 128 AINN1 PDWN AINP2 DRDY/DOUT AINN2 Input PGA DS ADC Mux SCLK AINP3 AINN3 Internal Oscillator ADS1234 Only AINP4 SPEED External Oscillator AINN4 (1) A1/TEMP A0 AGND CAP CLKIN/XTAL1 XTAL2 DGND NOTE: (1) A1 for ADS1234, TEMP for ADS1232.1 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.2 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 Copyright © 2005–2008, Texas Instruments IncorporatedInstruments standard warranty. Production processing does notnecessarily include testing of all parameters.
  2. 2. ADS1232ADS1234 www.ti.comSBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 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 INFORMATIONFor the most current package and ordering information, see the Package Option Addendum at the end of thisdata sheet, or see the TI website at www.ti.com.ABSOLUTE MAXIMUM RATINGSover operating free-air temperature range (unless otherwise noted) (1) ADS1232, ADS1234 UNITAVDD to AGND –0.3 to +6 VDVDD to DGND –0.3 to +6 VAGND to DGND –0.3 to +0.3 VInput Current 100, Momentary mAInput Current 10, Continuous mAAnalog Input Voltage to AGND –0.3 to AVDD + 0.3 VDigital Input Voltage to DGND –0.3 to DVDD + 0.3 VMaximum Junction Temperature +150 °COperating Temperature Range –40 to +105 °CStorage Temperature Range –60 to +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 under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.2 Copyright © 2005–2008, Texas Instruments Incorporated Product Folder Link(s): ADS1232 ADS1234
  3. 3. ADS1232 ADS1234 www.ti.com SBAS350F – JUNE 2005 – REVISED FEBRUARY 2008ELECTRICAL CHARACTERISTICSAll specifications at TA = –40°C to +105°C, AVDD = DVDD = VREFP = +5V, and VREFN = AGND, unless otherwise noted. ADS1232, ADS1234 PARAMETER CONDITIONS MIN TYP MAX UNITAnalog InputsFull-Scale Input Voltage ±0.5VREF/Gain V(AINP – AINN) AINxP or AINxN with respect to GND, AGND – 0.1 AVDD + 0.1 VCommon-Mode Input Range Gain = 1, 2 Gain = 64, 128 AGND + 1.5V AVDD – 1.5V V Gain = 1 ±3 nADifferential Input Current Gain = 2 ±6 nA Gain = 64, 128 ±3.5 nASystem PerformanceResolution No Missing Codes 24 Bits Internal Oscillator, SPEED = High 78 80 82.4 SPS Internal Oscillator, SPEED = Low 9.75 10 10.3 SPSData Rate External Oscillator, SPEED = High fCLK/61,440 SPS External Oscillator, SPEED = Low fCLK/491,520 SPSDigital Filter Settling Time Full Settling 4 Conversions Differential Input, End-Point Fit ±0.0002 ±0.001 % of FSR (1) Gain = 1, 2Integral Nonlinearity (INL) Differential Input, End-Point Fit ±0.0004 % of FSR Gain = 64, 128 Gain = 1 ±0.2 ±5 ppm of FSInput Offset Error (2) Gain = 128 ±0.02 ±1 ppm of FS Gain = 1 ±0.3 µV/°CInput Offset Drift Gain = 128 ±10 nV/°C (3) Gain = 1 ±0.001 ±0.02 %Gain Error Gain = 128 ±0.01 ±0.1 % Gain = 1 ±0.2 ppm/°CGain Drift Gain = 128 ±2.5 ppm/°C Internal Oscillator, fDATA = 10SPS 100 110 dB fIN = 50Hz or 60Hz, ±1HzNormal-Mode Rejection (4) External Oscillator, fDATA = 10SPS 120 130 dB fIN = 50Hz or 60Hz, ±1Hz at DC, Gain = 1, ΔV = 1V 95 110 dBCommon-Mode Rejection at DC, Gain = 128, ΔV = 0.1V 95 110 dBInput-Referred Noise See Noise Performance Tables at DC, Gain = 1, ΔV = 1V 100 120 dBPower-Supply Rejection at DC, Gain = 128, ΔV = 0.1V 100 120 dBVoltage Reference InputVoltage Reference Input (VREF) VREF = VREFP – VREFN 1.5 AVDD AVDD + 0.1V VNegative Reference Input (VREFN) AGND – 0.1 VREFP – 1.5 VPositive Reference Input (VREFP) VREFN + 1.5 AVDD + 0.1 VVoltage Reference 10 nAInput Current(1) FSR = full-scale range = VREF/Gain.(2) Offset calibration can minimize these errors to the level of noise at any temperature.(3) Gain errors are calibrated at the factory (AVDD = +5V, all gains, TA = +25°C).(4) Specification is assured by the combination of design and final production test.Copyright © 2005–2008, Texas Instruments Incorporated 3 Product Folder Link(s): ADS1232 ADS1234
  4. 4. ADS1232ADS1234 www.ti.comSBAS350F – JUNE 2005 – REVISED FEBRUARY 2008ELECTRICAL CHARACTERISTICS (continued)All specifications at TA = –40°C to +105°C, AVDD = DVDD = VREFP = +5V, and VREFN = AGND, unless otherwise noted. ADS1232, ADS1234 PARAMETER CONDITIONS MIN TYP MAX UNITDigitalLogic Levels VIH 0.7 DVDD DVDD + 0.1 V VIL DGND 0.2 DVDD V VOH IOH = 1mA DVDD – 0.4 V VOL IOL = 1mA 0.2 DVDD VInput Leakage 0 < VIN < DVDD ±10 µAExternal Clock Input Frequency 0.2 4.9152 8 MHz(fCLKIN)Serial Clock Input Frequency (fSCLK) 5 MHzPower SupplyPower-Supply Voltage 2.7 5.3 V(AVDD, DVDD) Normal Mode, AVDD = 3V, 600 1300 µA Gain = 1, 2 Normal Mode, AVDD = 3V, 1350 2500 µA Gain = 64, 128 Normal Mode, AVDD = 5V,Analog Supply Current 650 1300 µA Gain = 1, 2 Normal Mode, AVDD = 5V, 1350 2500 µA Gain = 64, 128 Standby Mode 0.1 1 µA Power-Down 0.1 1 µA Normal Mode, DVDD = 3V, 60 95 µA Gain = 1, 2 Normal Mode, DVDD = 3V, 75 120 µA Gain = 64, 128 Normal Mode, DVDD = 5V, 95 130 µA Gain = 1, 2Digital Supply Current Normal mode, DVDD = 5V, 75 120 µA Gain = 64, 128 Standby Mode, SCLK = High, DVDD = 3V 45 80 µA Standby Mode, SCLK = High, DVDD = 5V 65 80 µA Power-Down 0.2 1.3 µA Normal Mode, AVDD = DVDD = 3V, 2 4.2 mW Gain = 1, 2 Normal Mode, AVDD = DVDD = 5V, 3.7 7.2 mW Gain = 1, 2Power Dissipation, Total Normal Mode, AVDD = DVDD = 3V, 4.3 7.9 mW Gain = 64, 128 Normal Mode, AVDD = DVDD = 5V, 7.1 13.1 mW Gain = 64, 128 Standby Mode, AVDD = DVDD = 5V 0.3 0.4 mW4 Copyright © 2005–2008, Texas Instruments Incorporated Product Folder Link(s): ADS1232 ADS1234
  5. 5. ADS1232 ADS1234 www.ti.com SBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 NOISE PERFORMANCEThe ADS1232/4 offer outstanding noise performance that can be optimized for a given full-scale range using theon-chip programmable gain amplifier. Table 1 through Table 4 summarize the typical noise performance withinputs shorted externally for different gains, data rates, and voltage reference values.The RMS and Peak-to-Peak noise are referred to the input. The Effective Number of Bits (ENOB) is defined as:• ENOB = ln (FSR/RMS noise)/ln(2)The Noise-Free Bits are defined as:• Noise-Free Bits = ln (FSR/Peak-to-Peak Noise)/ln(2)Where FSR (Full-Scale Range) = VREF/Gain Table 1. AVDD = 5V, VREF = 5V, Data Rate = 10SPS GAIN RMS NOISE PEAK-TO-PEAK NOISE (1) ENOB (RMS) NOISE-FREE BITS 1 420nV 1.79µV 23.5 21.4 2 270nV 900nV 23.1 21.4 64 19nV 125nV 22.0 19.2 128 17nV 110nV 21.1 18.4(1) Peak-to-peak noise data are based on direct measurement. Table 2. AVDD = 5V, VREF = 5V, Data Rate = 80SPS GAIN RMS NOISE PEAK-TO-PEAK NOISE (1) ENOB (RMS) NOISE-FREE BITS 1 1.36µV 8.3µV 21.8 19.2 2 850nV 5.5µV 21.5 18.8 64 48nV 307nV 20.6 18 128 44nV 247nV 19.7 17.2(1) Peak-to-peak noise data are based on direct measurement. Table 3. AVDD = 3V, VREF = 3V, Data Rate = 10SPS GAIN RMS NOISE PEAK-TO-PEAK NOISE (1) ENOB (RMS) NOISE-FREE BITS 1 450nV 2.8µV 22.6 20 2 325nV 1.8µV 22.1 19.7 64 20nV 130nV 21.2 18.5 128 18nV 115nV 20.3 17.6(1) Peak-to-peak noise data are based on direct measurement. Table 4. AVDD = 3V, VREF = 3V, Data Rate = 80SPS GAIN RMS NOISE PEAK-TO-PEAK NOISE (1) ENOB (RMS) NOISE-FREE BITS 1 2.2µV 12µV 20.4 17.9 2 1.2µV 6.8µV 20.2 17.8 64 54nV 340nV 19.7 17.1 128 48nV 254nV 18.9 16.5(1) Peak-to-peak noise data are based on direct measurement of 1024 samples.Copyright © 2005–2008, Texas Instruments Incorporated 5 Product Folder Link(s): ADS1232 ADS1234
  6. 6. ADS1232ADS1234 www.ti.comSBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 PIN CONFIGURATION DVDD 1 28 DRDY/DOUT DVDD 1 24 DRDY/DOUT DGND 2 27 SCLK DGND 2 23 SCLK CLKIN/XTAL1 3 26 PDWN CLKIN/XTAL1 3 22 PDWN XTAL2 4 25 SPEED XTAL2 4 21 SPEED DGND 5 24 GAIN1 DGND 5 20 GAIN1 DGND 6 23 GAIN0 DGND 6 19 GAIN0 A1 7 22 AVDD ADS1232 ADS1234 TEMP 7 18 AVDD A0 8 21 AGND A0 8 17 AGND CAP 9 20 REFP CAP 9 16 REFP CAP 10 19 REFN CAP 10 15 REFN AINP1 11 18 AINP2 AINP1 11 14 AINP2 AINN1 12 17 AINN2 AINN1 12 13 AINN2 AINP3 13 16 AINP4 AINN3 14 15 AINN46 Copyright © 2005–2008, Texas Instruments Incorporated Product Folder Link(s): ADS1232 ADS1234
  7. 7. ADS1232 ADS1234 www.ti.com SBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 PIN DESCRIPTIONS TERMINAL ANALOG/DIGITALNAME ADS1232 ADS1234 INPUT/OUTPUT DESCRIPTIONDVDD 1 1 Digital Digital Power Supply: 2.7V to 5.3VDGND 2 2 Digital Digital GroundCLKIN/ External Clock Input: typically 4.9152MHz. Tie low to activate internal oscillator. Can also use 3 3 Digital/Digital InputXTAL1 external crystal across CLKIN/XTAL1 and XTAL2 pins. See text for more details.XTAL2 4 4 Digital External crystal connectionDGND 5 5 Digital Digital GroundDGND 6 6 Digital Digital GroundTEMP 7 – Digital Input Onboard Temperature Diode Enable Input Mux Select Input pin (MSB) Input Mux Select Input pin (LSB): A1 A0 ChannelA1 – 7 Digital Input 0 0 AIN1A0 8 8 0 1 AIN2 1 0 AIN3 1 1 AIN4CAP 9 9 Analog Gain Amp Bypass Capacitor ConnectionCAP 10 10 Analog Gain Amp Bypass Capacitor ConnectionAINP1 11 11 Analog Input Positive Analog Input Channel 1AINN1 12 12 Analog Input Negative Analog Input Channel 1AINP3 – 13 Analog Input Positive Analog Input Channel 3AINN3 – 14 Analog Input Negative Analog Input Channel 3AINN4 – 15 Analog Input Negative Analog Input Channel 4AINP4 – 16 Analog Input Positive Analog Input Channel 4AINN2 13 17 Analog Input Negative Analog Input Channel 2AINP2 14 18 Analog Input Positive Analog Input Channel 2REFN 15 19 Analog Input Negative Reference InputREFP 16 20 Analog Input Positive Reference InputAGND 17 21 Analog Analog GroundAVDD 18 22 Analog Analog Power Supply, 2.7V to 5.3V Gain Select GAIN1 GAIN0 GAINGAIN0 19 23 0 0 1 Digital InputGAIN1 20 24 0 1 2 1 0 64 1 1 128 Data Rate Select: SPEED DATA RATESPEED 21 25 Digital Input 0 10SPS 1 80SPSPDWN 22 26 Digital Input Power-Down: Holding this pin low powers down the entire converter and resets the ADC. Serial Clock: Clock out data on the rising edge. Also used to initiate Offset Calibration and SleepSCLK 23 27 Digital Input modes. See text for more details. Dual-Purpose Output:DRDY/ 24 28 Digital Output Data Ready: Indicates valid data by going low.DOUT Data Output: Outputs data, MSB first, on the first rising edge of SCLK.Copyright © 2005–2008, Texas Instruments Incorporated 7 Product Folder Link(s): ADS1232 ADS1234
  8. 8. ADS1232ADS1234 www.ti.comSBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 TYPICAL CHARACTERISTICS At TA = +25°C, AVDD = DVDD = VREFP = 5V, and VREFN = AGND, unless otherwise noted. NOISE PLOT NOISE PLOT 6 25 PGA = 1 5 20 Data Rate = 10SPS 4 15 3 Output Code (LSB) Output Code (LSB) 10 2 5 1 0 −1 −5 −2 −10 −3 −4 −15 −20 PGA = 128 −5 Data Rate = 10SPS −6 −25 0 200 400 600 800 1000 0 200 400 600 800 1000 Time (Reading Number) Time (Reading Number) Figure 1. Figure 2. NOISE HISTOGRAM NOISE HISTOGRAM 300 100 PGA = 1 PGA = 128 Data Rate = 10SPS 90 Data Rate = 10SPS 250 80 70 200 Occurrence Occurrence 60 150 50 40 100 30 20 50 10 0 0 −4 −2 0 2 4 −16 −8 0 8 16 Output Code (LSB) Output Code (LSB) Figure 3. Figure 4. NOISE PLOT NOISE PLOT 22.5 70 PGA = 128 PGA = 1 17.5 Data Rate = 80SPS Data Rate = 80SPS 50 12.5 Output Code (LSB) 30 Output Code(LSB) 7.5 2.5 10 −2.5 −10 −7.5 −30 −12.5 −50 −17.5 −22.5 −70 0 200 400 600 800 1000 0 200 400 600 800 1000 Time (Reading Number) Time (Reading Number) Figure 5. Figure 6.8 Copyright © 2005–2008, Texas Instruments Incorporated Product Folder Link(s): ADS1232 ADS1234
  9. 9. ADS1232 ADS1234 www.ti.com SBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 TYPICAL CHARACTERISTICS (continued)At TA = +25°C, AVDD = DVDD = VREFP = 5V, and VREFN = AGND, unless otherwise noted. NOISE HISTOGRAM NOISE HISTOGRAM 180 50 PGA = 1 PGA = 128 160 45 Data Rate = 80SPS Data Rate = 80SPS 140 40 35 120 Occurance Occurance 30 100 25 80 20 60 15 40 10 20 5 0 0 −12 −6 0 6 12 −40 −20 0 20 40 Output Code (LSB) Output Code (LSB) Figure 7. Figure 8. OFFSET DRIFT (–40°C to +25°C) OFFSET DRIFT (+25°C to +105°C) 35 35 PGA = 1 PGA = 1 30 Data Rate = 10SPS 30 Data Rate = 10SPS 90 Samples from 3 Lots 90 Samples from 3 Lots 25 25 20 20 Counts Counts 15 15 10 10 5 5 0 0 -600 -500 -400 -300 -200 -100 0 100 200 300 400 500 600 -500 -400 -300 -200 -100 0 100 200 300 400 500 Offset Drift (nV/°C) Offset Drift (nV/°C) Figure 9. Figure 10. GAIN DRIFT (–40°C to +25°C) GAIN DRIFT (+25°C to +105°C) 18 20 PGA = 1 PGA = 1 16 Data Rate = 10SPS 18 Data Rate = 10SPS 90 Samples from 3 Lots 16 90 Samples from 3 Lots 14 12 14 12 Counts Counts 10 10 8 8 6 6 4 4 2 2 0 0 -1.2 -1.1 -1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 -1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Gain Drift (ppm/°C) Gain Drift (ppm/°C) Figure 11. Figure 12.Copyright © 2005–2008, Texas Instruments Incorporated 9 Product Folder Link(s): ADS1232 ADS1234
  10. 10. ADS1232ADS1234 www.ti.comSBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 TYPICAL CHARACTERISTICS (continued)At TA = +25°C, AVDD = DVDD = VREFP = 5V, and VREFN = AGND, unless otherwise noted. OFFSET DRIFT (–40°C to +25°C) OFFSET DRIFT (+25°C to +105°C) 30 20 PGA = 128 PGA = 128 Data Rate = 10SPS 18 Data Rate = 10SPS 25 90 Samples from 3 Lots 16 90 Samples from 3 Lots 20 14 12 Counts Counts 15 10 8 10 6 5 4 2 0 0 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 -50 -40 -30 -20 -10 0 10 20 30 40 Offset Drift (nV/°C) 50 Offset Drift (nV/°C) Figure 13. Figure 14. GAIN DRIFT (–40°C to +25°C) GAIN DRIFT (+25°C to +105°C) 25 20 PGA = 128 PGA = 128 Data Rate = 10SPS 18 Data Rate = 10SPS 20 90 Samples from 3 Lots 16 90 Samples from 3 Lots 14 15 12 Counts Counts 10 10 8 6 5 4 2 0 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Gain Drift (ppm/°C) Gain Drift (ppm/°C) Figure 15. Figure 16. OFFSET vs TEMPERATURE GAIN ERROR vs TEMPERATURE 1000 0.04 PGA = 128 PGA = 128 Data Rate = 10SPS Data Rate = 10SPS 0.03 500 0.02 Gain Error (%) Offset (nV) 0 0.01 0 −500 −0.01 −1000 −0.02 −50 −30 −10 10 30 50 70 90 110 −50 −30 −10 10 30 50 70 90 110 Temperature (_C) Temperature (_C) Figure 17. Figure 18.10 Copyright © 2005–2008, Texas Instruments Incorporated Product Folder Link(s): ADS1232 ADS1234
  11. 11. ADS1232 ADS1234 www.ti.com SBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 TYPICAL CHARACTERISTICS (continued)At TA = +25°C, AVDD = DVDD = VREFP = 5V, and VREFN = AGND, unless otherwise noted. NOISE vs INPUT SIGNAL NOISE vs INPUT SIGNAL 1000 50 PGA = 1 PGA = 128 900 45 Data Rate = 10SPS Data Rate = 10SPS 800 40 700 35 RMS Noise (nV) RMS Noise (nV) 600 30 500 25 400 20 300 15 200 10 100 5 0 0 −2.5 −2.0 −1.5 −1.0 −0.5 0 0.5 1.0 1.5 2.0 2.5 −19 −14.25 −9.5 −4.75 0 4.75 9.5 14.25 19 VIN (V) VIN (mV) Figure 19. Figure 20. INTEGRAL NONLINEARITY INTEGRAL NONLINEARITY vs INPUT SIGNAL vs INPUT SIGNAL 5 25 10 390.625 PGA = 1 PGA = 128 4 20 8 312.5 3 15 6 234.375 2 10 4 156.25 INL (ppm of FSR) INL (ppmof FSR) 1 5 2 78.125 INL (µV) INL (nV) 0 0 0 0 −1 −5 −2 −78.125 −2 −10 −4 −156.25 −3 −15 −6 −234.375 −4 −20 −8 −312.5 −5 −25 −10 −390.625 −2.5 −2.0 −1.5 −1.0 −0.5 0 0.5 1.0 1.5 2.0 2.5 −19 −14.25 −9.5 −4.75 0 4.75 9.5 14.25 19 VIN (V) VIN (mV) Figure 21. Figure 22. ANALOG CURRENT DIGITAL CURRENT vs TEMPERATURE vs TEMPERATURE 2000 120 Normal Mode, PGA = 64, 128 Normal Mode, PGA = 1, 2 100 1600 Analog Current (µA) Digital Current (µA) Normal Mode, PGA = 64, 128 80 1200 Sleep Mode, All PGAs 60 Normal Mode, PGA = 1, 2 800 40 400 20 0 0 −50 −30 −10 10 30 50 70 90 110 −50 −30 −10 10 30 50 70 90 110 Temperature (_C) Temperature (_C) Figure 23. Figure 24.Copyright © 2005–2008, Texas Instruments Incorporated 11 Product Folder Link(s): ADS1232 ADS1234
  12. 12. ADS1232ADS1234 www.ti.comSBAS350F – JUNE 2005 – REVISED FEBRUARY 2008 TYPICAL CHARACTERISTICS (continued)At TA = +25°C, AVDD = DVDD = VREFP = 5V, and VREFN = AGND, unless otherwise noted. DATA RATE vs TEMPERATURE 10.06 SPEED = LOW CLKIN/XTAL1 = LOW (Internal Oscillator) 10.01 Data Rate (SPS) 9.96 9.91 9.86 −50 −30 −10 10 30 50 70 90 110 Temperature (_C) Figure 25.12 Copyright © 2005–2008, Texas Instruments Incorporated Product Folder Link(s): ADS1232 ADS1234
  13. 13. ADS1232 ADS1234 www.ti.com SBAS350F – JUNE 2005 – REVISED FEBRUARY 2008OVERVIEW TEMPERATURE SENSOR (ADS1232 only)The ADS1232 and ADS1234 are highly integrated, On-chip diodes provide temperature-sensing24-bit ADCs that include an input multiplexer, capability. By setting the TEMP pin high, the selectedlow-noise PGA, third-order delta-sigma (ΔΣ) analog inputs are disconnected and the inputs to themodulator, and fourth-order digital filter. With ADC are connected to the anodes of two diodesinput-referred RMS noise down to 17nV, the scaled to 1x and 80x in current and size, as shown inADS1232/4 are ideally suited for measuring the very Figure 26. By measuring the difference in voltage oflow signals produced by bridge sensors in these diodes, temperature changes can be inferredapplications such as weigh scales, strain gauges, and from a baseline temperature. Typically, the differencepressure sensors. in diode voltage is 111.7mV at 25°C with a temperature coefficient of 379µV/°C. With PGA = 1Clocking can be supplied by an external oscillator, an and 2, the difference voltage output from the PGA willexternal crystal, or by a precision internal oscillator. be 111.7mV and 223.4mV, respectively. With PGA =Data can be output at 10SPS for excellent 50Hz and 64 and 128, it is impossible to use the temperature60Hz rejection, or at 80SPS when higher speeds are sensor function. A similar structure is used in theneeded. The ADS1232/4 are easy to configure, and MSC1210 for temperature measurement. For moreall digital control is accomplished through dedicated information, see TI application report SBAA100,pins; there are no registers to program. A simple Using the MSC121x as a High-Precision Intelligenttwo-wire serial interface retrieves the data. Temperature Sensor, available for download at www.ti.com.ANALOG INPUTS (AINPx, AINNx)The input signal to be measured is applied to theinput pins AINPx and AINNx. The positive internalinput is generalized as AINP, and the negative ADS1232 Onlyinternal input generalized as AINN. The signal is AVDDselected through the input mux, which is controlled bypins A0 and A1 (ADS1234 only), as shown inTable 5. For the ADS1232, the A1 pin is replaced by 10I 1Ithe TEMP pin to activate the onboard diodes (see theTemperature Sensor section for more details). The AINPADS1232/4 accept differential input signals, but can AINNalso measure unipolar signals. When measuringunipolar (or single-ended signals) with respect to 1X 8Xground, connect the negative input (AINNx) to groundand connect the input signal to the positive input(AINPx). Note that when the ADS1232/4 areconfigured this way, only half of the converterfull-scale range is used, since only positive digital AINP1output codes are produced. AINN1 AINP2 Table 5. Input Channel Selection with A0 and A1 AINN2 (ADS1234 only) AINP3 MUX PINS SELECTED ANALOG INPUTS AINN3 A1 A0 POSITIVE INPUT NEGATIVE INPUT AINP4 0 0 AINP1 AINN1 AINN4 0 1 AINP2 AINN2 1 0 AINP3 AINN3 ADS1234 Only A1 A0 1 1 AINP4 AINN3 Figure 26. Measurement of the Temperature Sensor in the Input MultiplexerCopyright © 2005–2008, Texas Instruments Incorporated 13 Product Folder Link(s): ADS1232 ADS1234

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