ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 24-Bit Analog-to-Digital Converters for Temperature Sensors Check for Samples: ADS1246, ADS1247, ADS1248 FEATURES 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 (ΔΣ) 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 sensor applications including thermal couples, thermistors, and RTDs. 1 23 • • • • • • • • • 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 Single-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) Sensor Burnout Detection 4/8 General-Purpose I/Os (ADS1247/8) Internal Temperature Sensor Power Supply and VREF Monitoring (ADS1247/8) Self and System Calibration SPI™-Compatible Serial Interface Analog Supply Unipolar (+2.7V to +5.25V)/Bipolar (±2.5V) Operation Digital Supply: +2.7V to +5.25V Operating Temperature –40°C to +125°C APPLICATIONS • • • Temperature Measurement – RTDs, Thermocouples, and Thermistors Pressure Measurement Industrial Process Control REFP AVDD REFN 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 ΔΣ modulator and adjustable 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 rejected by the filter. 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 rated over the extended specified temperature range of –40°C to +105°C. DVDD Burnout Detect AVDD REFP0/ REFN0/ ADS1248 Only GPIO0 GPIO1 REFP1 REFN1 VREFOUT VREFCOM Burnout Detect ADS1246 VBIAS Voltage Reference VREF Mux VBIAS DVDD ADS1247 ADS1248 GPIO SCLK DIN AIN0 AIN1 Input Mux PGA 3rd Order DS Modulator Adjustable Digital Filter Serial Interface and Control DRDY DOUT/DRDY CS START RESET Internal Oscillator AIN0/IEXC AIN1/IEXC SCLK System Monitor AIN2/IEXC/GPIO2 AIN3/IEXC/GPIO3 Input Mux AIN4/IEXC/GPIO4 AIN5/IEXC/GPIO5 PGA DIN 3rd Order DS Modulator Dual Current DACs AIN6/IEXC/GPIO6 AIN7/IEXC/GPIO7 ADS1248 Only Adjustable Digital Filter Serial Interface and Control DRDY DOUT/DRDY CS START RESET Internal Oscillator Burnout Detect Burnout Detect AVSS CLK DGND AVSS IEXC1 IEXC2 ADS1248 Only CLK DGND 1 2 3 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. 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 © 2008–2010, Texas Instruments Incorporated ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 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) (1) PRODUCT NUMBER OF INPUTS VOLTAGE REFERENCE DUAL SENSOR EXCITATION CURRENT SOURCES ADS1246 1 Differential or 1 Single-Ended External NO TSSOP-16 ADS1247 2 Differential or 3 Single-Ended Internal or External YES TSSOP-20 ADS1248 4 Differential or 7 Single-Ended Internal or External YES TSSOP-28 PACKAGELEAD 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 Input current 100, momentary mA 10, continuous mA Analog input voltage to AVSS AVSS – 0.3 AVDD + 0.3 Digital input voltage to DGND –0.3 DVDD + 0.3 V +150 °C Maximum junction temperature V Operating temperature range –40 +125 °C Storage temperature range –60 +150 °C (1) 2 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. Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 THERMAL INFORMATION ADS1246, ADS1247, ADS1248 THERMAL METRIC (1) UNITS TSSOP (IPW) 28 qJA Junction-to-ambient thermal resistance (2) qJC(top) Junction-to-case(top) thermal resistance 54.6 (3) 11.3 (4) qJB Junction-to-board thermal resistance yJT Junction-to-top characterization parameter yJB Junction-to-board characterization parameter qJC(bottom) (1) (2) (3) (4) (5) (6) (7) 13.0 (5) Junction-to-case(bottom) thermal resistance 0.5 (6) (7) °C/W 12.7 n/a For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. 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. 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. 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. The junction-to-top characterization parameter, yJT, estimates the junction temperature of a device in a real system and is extracted from the simulation data for obtaining qJA, using a procedure described in JESD51-2a (sections 6 and 7). The junction-to-board characterization parameter, yJB estimates the junction temperature of a device in a real system and is extracted from the simulation data for obtaining qJA , using a procedure described in JESD51-2a (sections 6 and 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 © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 3 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com 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, VREF = +2.048V, and oscillator frequency = 4.096MHz, unless otherwise noted. ADS1246, ADS1247, ADS1248 PARAMETER CONDITIONS MIN TYP MAX ±VREF/PGA 2.7/PGA UNIT ANALOG INPUTS Full-scale input voltage (VIN = ADCINP – ADCINN) (VIN)(Gain) AVSS + 0.1V + Common-mode input range 2 Differential input current AVDD - 0.1V - (VIN)(Gain) 2 100 Absolute input current V V pA See Table 11 PGA gain settings 1, 2, 4, 8, 16, 32, 64, 128 Burnout current source Bias voltage 0.5, 2, or 10 mA (AVDD + AVSS)/2 V 400 Ω Bias voltage output impedance SYSTEM PERFORMANCE Resolution No missing codes Data rate Integral nonlinearity (INL) Differential input, end point fit, PGA = 1 Offset error After calibration (1) Offset drift Gain error 24 Bits 5, 10, 20, 40, 80, 160, 320, 640, 1000, 2000 6 SPS 15 –15 15 See Figure 11 to Figure 14 T = +25°C, all PGAs, data rate = 40, 80, or 160SPS Gain drift –0.02 ±0.005 mV nV/°C 0.02 See Figure 19 to Figure 22 ADC conversion time ppm % ppm/°C Single-cycle settling Noise See Table 5 to Table 8 Normal-mode rejection Common-mode rejection Power-supply rejection See Table 13 At dc, PGA = 1 80 90 dB At dc, PGA = 32 90 125 dB 100 135 dB AVDD/DVDD at dc, PGA = 32, data rate = 80SPS VOLTAGE REFERENCE INPUT Voltage reference input (VREF = VREFP – VREFN) 0.5 (AVDD – AVSS) – 1 V V Negative reference input (REFN) AVSS – 0.1 REFP – 0.5 Positive reference input (REFP) REFN + 0.5 AVDD + 0.1 Reference input current 30 V nA ON-CHIP VOLTAGE REFERENCE Output voltage 2.038 2.048 Output current (2) Load regulation TA = –40°C to +105°C Startup time (1) (2) (3) 4 V ±10 mA 2 10 ppm/°C 6 15 ppm/°C 50 TA = +25°C to +105°C Drift (3) 2.058 See Table 14 mV/mA ms Offset calibration on the order of noise. Do not exceed this loading on the internal voltage reference. Specified by the combination of design and final production test. Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 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, VREF = +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 Voltage compliance All currents Initial error All currents, each IDAC Initial mismatch All currents, between IDACs Temperature drift Each IDAC Temperature drift matching Between IDACs mA AVDD – 0.7 –6 ±1.0 V 6 % of FS ±0.15 % of FS 100 ppm/°C 10 ppm/°C SYSTEM MONITORS Temperature sensor reading Voltage TA = +25°C Drift 118 mV 405 mV/°C GENERAL-PURPOSE INPUT/OUTPUT (GPIO) Logic levels VIH 0.7AVDD AVDD V VIL AVSS 0.3AVDD V VOH IOH = 1mA VOL IOL = 1mA 0.8AVDD V 0.2 AVDD V DIGITAL INPUT/OUTPUT (other than GPIO) Logic levels VIH 0.7DVDD DVDD V VIL DGND 0.3DVDD V VOH IOH = 1mA 0.8DVDD VOL IOL = 1mA DGND Input leakage Clock input (CLK) V DGND < VIN < DVDD 0.2 DVDD V ±10 mA MHz Frequency 1 4.5 Duty cycle 25 75 % 4.3 MHz Internal oscillator frequency 3.89 4.096 POWER SUPPLY DVDD 2.7 5.25 V AVSS –2.5 0 V AVDD AVSS + 2.7 AVSS + 5.25 V DVDD current AVDD current Power dissipation Normal mode, DVDD = 5V, data rate = 20SPS, internal oscillator 230 mA Normal mode, DVDD = 3.3V, data rate = 20SPS, internal oscillator 210 mA Sleep mode 0.2 µA Converting, AVDD = 5V, data rate = 20SPS, external reference 225 µA Converting, AVDD = 3.3V, data rate = 20SPS, external reference 200 µA Sleep mode 0.1 µA Additional current with internal reference enabled 180 mA AVDD = DVDD = 5V, data rate = 20SPS, internal oscillator, external reference 2.3 mW AVDD = DVDD = 3.3V, data rate = 20SPS, internal oscillator, external reference 1.4 mW TEMPERATURE RANGE Specified –40 +105 °C Operating –40 +125 °C Storage –60 +150 °C Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 5 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com PIN CONFIGURATIONS PW PACKAGE TSSOP-28 (TOP VIEW) 6 DVDD 1 28 SCLK DGND 2 27 DIN CLK 3 26 DOUT/DRDY RESET 4 25 DRDY REFP0/GPIO0 5 24 CS REFN0/GPIO1 6 23 START REFP1 7 22 AVDD REFN1 8 21 AVSS VREFOUT 9 20 IEXC1 VREFCOM 10 19 IEXC2 AIN0/IEXC 11 18 AIN3/IEXC/GPIO3 AIN1/IEXC 12 17 AIN2/IEXC/GPIO2 AIN4/IEXC/GPIO4 13 16 AIN7/IEXC/GPIO7 AIN5/IEXC/GPIO5 14 15 AIN6/IEXC/GPIO6 Submit Documentation Feedback ADS1248 Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 ADS1248 (TSSOP-28) PIN DESCRIPTIONS NAME PIN NO. FUNCTION DVDD 1 Digital Digital power supply DESCRIPTION DGND 2 Digital Digital ground CLK 3 Digital input External clock input. Tie this pin to DGND to activate the internal oscillator. RESET 4 Digital input Chip reset (active low). Returns all register values to reset values. REFP0/GPIO0 5 Analog input Digital in/out Positive external reference input 0, or general-purpose digital input/output pin 0 REFN0/GPIO1 6 Analog input Digital in/out Negative external reference 0 input, or general-purpose digital input/output pin 1 REFP1 7 Analog input Positive external reference 1 input REFN1 8 Analog input Negative external reference 1 input VREFOUT 9 Analog output Positive internal reference voltage output VREFCOM 10 Analog output Negative internal reference voltage output. Connect this pin to AVSS when using a unipolar supply, or to the midvoltage of the power supply when using a bipolar supply. AIN0/IEXC 11 Analog input Analog input 0, optional excitation current output AIN1/IEXC 12 Analog input Analog input 1, optional excitation current output AIN4/IEXC/GPIO4 13 Analog input Digital in/out Analog input 4, optional excitation current output, or general-purpose digital input/output pin 4 AIN5/IEXC/GPIO5 14 Analog input Digital in/out Analog input 5, optional excitation current output, or general-purpose digital input/output pin 5 AIN6/IEXC/GPIO6 15 Analog input Digital in/out Analog input 6, optional excitation current output, or general-purpose digital input/output pin 6 AIN7/IEXC/GPIO7 16 Analog input Digital in/out Analog input 7, optional excitation current output, or general-purpose digital input/output pin 7 AIN2/IEXC/GPIO2 17 Analog input Digital in/out Analog input 2, optional excitation current output, or general-purpose digital input/output pin 2 AIN3/IEXC/GPIO3 18 Analog input Digital in/out Analog input 3, optional excitation current output, or general-purpose digital input/output pin 3 IOUT2 19 Analog output Excitation current output 2 IOUT1 20 Analog output Excitation current output 1 AVSS 21 Analog Negative analog power supply AVDD 22 Analog Positive analog power supply START 23 Digital input Conversion start. See text for complete description. CS 24 Digital input Chip select (active low) DRDY 25 Digital output Data ready (active low) DOUT/DRDY 26 Digital output Serial Data Out Output, or Data Out combined with Data Ready (active low when DRDY function enabled) DIN 27 Digital input Serial data input SCLK 28 Digital input Serial clock input Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 7 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com PW PACKAGE TSSOP-20 (TOP VIEW) DVDD 1 20 SCLK DGND 2 19 DIN CLK 3 18 DOUT/DRDY RESET 4 17 DRDY REFP0/GPIO0 5 16 CS REFN0/GPIO1 6 15 START VREFOUT 7 14 AVDD VREFCOM 8 13 AVSS AIN0/IEXC 9 12 AIN3/IEXC/GPIO3 AIN1/IEXC 10 11 AIN2/IEXC/GPIO2 ADS1247 ADS1247 (TSSOP-20) PIN DESCRIPTIONS NAME PIN NO. FUNCTION DVDD 1 Digital Digital power supply DGND 2 Digital Digital ground CLK 3 Digital input External clock input. Tie this pin to DGND to activate the internal oscillator. RESET 4 Digital input Chip reset (active low). Returns all register values to reset values. REFP0/GPIO0 5 Analog input Digital in/out Positive external reference input, or general-purpose digital input/output pin 0 REFN0/GPIO1 6 Analog input Digital in/out Negative external reference input, or general-purpose digital input/output pin 1 VREFOUT 7 Analog output Positive internal reference voltage output VREFCOM 8 Analog output Negative internal reference voltage output. Connect this pin to AVSS when using a unipolar supply, or to the midvoltage of the power supply when using a bipolar supply. AIN0/IEXC 9 Analog input Analog input 0, optional excitation current output AIN1/IEXC 10 Analog input Analog input 1, optional excitation current output AIN2/IEXC/GPIO2 11 Analog input Digital in/out Analog input 2, optional excitation current output, or general-purpose digital input/output pin 2 AIN3/IEXC/GPIO3 12 Analog input Digital in/out Analog input 3, with or without excitation current output, or general-purpose digital input/output pin 3 AVSS 13 Analog Negative analog power supply AVDD 14 Analog Positive analog power supply START 15 Digital input Conversion start. See text for description of use. CS 16 Digital input Chip select (active low) DRDY 17 Digital output Data ready (active low) DOUT/DRDY 18 Digital output Serial data out output, or Data out combined with Data Ready (active low when DRDY function enabled) DIN 19 Digital input Serial data input SCLK 20 Digital input Serial clock input 8 Submit Documentation Feedback DESCRIPTION Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 PW PACKAGE TSSOP-16 (TOP VIEW) DVDD 1 16 SCLK DGND 2 15 DIN CLK 3 14 DOUT/DRDY RESET 4 13 DRDY REFP 5 12 CS REFN 6 11 START AINP 7 10 AVDD AINN 8 9 AVSS ADS1246 ADS1246 (TSSOP-16) PIN DESCRIPTIONS NAME PIN NO. FUNCTION DVDD 1 Digital Digital power supply DESCRIPTION DGND 2 Digital Digital ground CLK 3 Digital input External clock input. Tie this pin to DGND to activate the internal oscillator. RESET 4 Digital input Chip reset (active low). Returns all register values to reset values. REFP 5 Analog input Positive external reference input REFN 6 Analog input Negative external reference input AINP 7 Analog input Positive analog input AINN 8 Analog input Negative analog input AVSS 9 Analog Negative analog power supply AVDD 10 Analog Positive analog power supply START 11 Digital input Conversion start. See text for description of use. CS 12 Digital input Chip select (active low) DRDY 13 Digital output Data ready (active low) DOUT/DRDY 14 Digital output Serial data out output, or Data out combined with Data Ready (active low when DRDY function enabled) DIN 15 Digital input Serial data input SCLK 16 Digital input Serial clock input Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 9 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com TIMING DIAGRAMS CS tCSSC tSPWH tSCLK tSCCS SCLK DIN DIN[0] tSPWL tDIHD tDIST DIN[7] DIN[6] DIN[5] DIN[4] DIN[1] tDOPD DOUT/DRDY (1) DOUT[7] DOUT[6] DIN[0] tDOHD DOUT[5] DOUT[4] DOUT[1] DOUT[0] tCSDO Figure 1. Serial Interface Timing Table 1. Timing Characteristics for Figure 1 SYMBOL (1) DESCRIPTION tCSSC CS low to first SCLK high (set up time) tSCCS MIN MAX UNIT 10 ns SCLK low to CS high (hold time) 7 tOSC tDIST DIN set up time 5 ns tDIHD DIN hold time 5 ns tDOPD SCLK rising edge to new data valid tDOHD DOUT hold time 30 0 (2) ns ns 500 ns tSCLK SCLK period tSPWH SCLK pulse width high 0.25 0.75 tSCLK tSPWL SCLK pulse width low 0.25 0.75 tSCLK tCSDO CS high to DOUT high impedance (1) (2) 64 10 Conversions ns DRDY MODE bit = 0. tOSC = 1/fCLK. The default clock frequency fCLK = 4.096MHz. tDTS tPWH DRDY 1 2 3 4 5 6 7 8 tSTD SCLK(3) Figure 2. SPI Interface Timing to Allow Conversion Result Loading (3) (4) Table 2. Timing Characteristics for Figure 2 SYMBOL DESCRIPTION MIN MAX UNIT tPWH DRDY pulse width high 3 tOSC tSTD SCLK low prior to DRDY low 5 tOSC tDTS DRDY falling edge to SCLK rising edge 30 ns (3) (4) 10 This timing diagram is applicable only when the CS pin is low. SCLK need not be low during tSTD when CS is high. SCLK should only be sent in multiples of eight during partial retrieval of output data. Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 tSTART START Figure 3. Minimum START Pulse Width Table 3. Timing Characteristics for Figure 3 SYMBOL tSTART DESCRIPTION MIN START pulse width high MAX 3 UNIT tOSC tRESET RESET CS SCLK tRHSC Figure 4. Reset Pulse Width and SPI Communication After Reset Table 4. Timing Characteristics for Figure 4 SYMBOL DESCRIPTION MIN t RESET RESET pulse width low 4 tOSC tRHSC RESET high to SPI communication start 0.6 (1) ms (1) MAX UNIT Applicable only when fOSC = 4.096MHz and scales proportionately with fOSC frequency. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 11 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com NOISE PERFORMANCE The ADS1246/7/8 noise performance can be optimized by adjusting the data rate and PGA setting. As the averaging is increased by reducing the data rate, the noise drops correspondingly. Increasing the PGA value reduces the input-referred noise, particularly useful when measuring low-level signals. Table 5 to Table 10 summarize noise performance of the ADS1246/7/8. The data are representative of typical noise performance at T = +25°C. The data shown are the result of averaging the readings from multiple devices and were measured with the inputs shorted together. A minimum of 128 consecutive readings were used to calculate the RMS and peak-to-peak noise for each reading. Table 5, Table 7, and Table 9 list the input-referred noise in units of mVRMS and mVPP for the conditions shown. Table 6, Table 8, and Table 10 list the corresponding data in units of ENOB (effective number of bits) where: ENOB = ln(Full-Scale Range/Noise)/ln(2) (1) Table 7 to Table 10 use the internal reference available on the ADS1247 and ADS1248. The data though are also representative of the ADS1246 noise performance when using a low-noise external reference such as the REF5020. 12 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 Table 5. Noise in mVRMS and (mVPP) at AVDD = 5V, AVSS = 0V, and External Reference = 2.5V DATA RATE (SPS) PGA SETTING 1 2 4 8 16 32 64 128 5 1.10 (4.99) 0.68 (3.80) 0.37 (1.90) 0.19 (0.98) 0.10 (0.44) 0.07 (0.31) 0.05 (0.27) 0.05 (0.21) 10 1.53 (8.82) 0.82 (3.71) 0.50 (2.69) 0.27 (1.33) 0.15 (0.67) 0.08 (0.50) 0.06 (0.36) 0.07 (0.34) 20 2.32 (13.37) 1.23 (6.69) 0.71 (3.83) 0.34 (1.90) 0.18 (1.01) 0.12 (0.71) 0.10 (0.51) 0.09 (0.54) 40 2.72 (17.35) 1.33 (7.65) 0.68 (3.83) 0.38 (2.21) 0.22 (1.13) 0.14 (0.77) 0.15 (0.78) 0.14 (0.76) 80 3.56 (22.67) 1.87 (12.30) 0.81 (5.27) 0.50 (3.49) 0.30 (1.99) 0.19 (1.24) 0.19 (1.16) 0.18 (1.04) 160 5.26 (42.03) 2.52 (17.57) 1.32 (9.22) 0.67 (5.25) 0.41 (2.89) 0.26 (1.91) 0.27 (1.74) 0.26 (1.74) 320 9.39 (74.91) 4.68 (39.48) 2.69 (18.95) 1.24 (9.94) 0.68 (5.25) 0.45 (3.08) 0.38 (2.71) 0.36 (2.46) 640 13.21 (119.66) 6.93 (59.31) 3.59 (28.55) 1.53 (10.68) 0.95 (8.70) 0.63 (4.94) 0.53 (3.74) 0.50 (3.55) 1000 32.34 (443.91) 16.11 (185.67) 11.54 (92.23) 4.65 (37.55) 2.02 (23.14) 1.15 (12.29) 0.77 (7.42) 0.64 (4.98) 2000 32.29 (372.54) 15.99 (182.27) 8.02 (91.73) 4.08 (45.89) 2.19 (24.14) 1.36 (12.32) 1.08 (8.03) 1.00 (6.93) Table 6. Effective Number of Bits From RMS Noise and (Peak-to-Peak Noise) at AVDD = 5V, AVSS = 0V, and External Reference = 2.5V DATA RATE (SPS) PGA SETTING 1 2 4 8 16 32 64 128 5 21.8 (19.6) 21.5 (19.0) 21.4 (19.0) 21.4 (19.0) 21.3 (19.2) 20.9 (18.7) 20.2 (17.8) 19.4 (17.2) 10 21.4 (18.8) 21.3 (19.1) 21.0 (18.5) 20.8 (18.6) 20.7 (18.6) 20.6 (18.0) 19.9 (17.5) 18.9 (16.5) 20 20.8 (18.2) 20.7 (18.2) 20.5 (18.0) 20.5 (18.0) 20.4 (18.0) 20.0 (17.5) 19.3 (16.9) 18.4 (15.9) 40 20.5 (17.8) 20.6 (18.0) 20.5 (18.0) 20.4 (17.8) 20.2 (17.8) 19.8 (17.4) 18.7 (16.3) 17.8 (15.4) 80 20.1 (17.5) 20.1 (17.3) 20.3 (17.6) 20.0 (17.2) 19.7 (17.0) 19.4 (16.7) 18.4 (15.7) 17.5 (14.9) 160 19.6 (16.6) 19.6 (16.8) 19.6 (16.8) 19.5 (16.6) 19.3 (16.4) 18.9 (16.0) 17.9 (15.2) 16.9 (14.2) 320 18.7 (15.7) 18.7 (15.7) 18.5 (15.7) 18.7 (15.7) 18.5 (15.6) 18.1 (15.3) 17.4 (14.5) 16.5 (13.7) 640 18.2 (15.1) 18.2 (15.1) 18.1 (15.1) 18.4 (15.5) 18.0 (14.8) 17.6 (14.7) 16.9 (14.1) 16.0 (13.1) 1000 17.0 (13.2) 17.0 (13.4) 16.4 (13.4) 16.7 (13.7) 17.0 (13.4) 16.8 (13.3) 16.4 (13.1) 15.6 (12.6) 2000 17.0 (13.4) 17.0 (13.5) 17.0 (13.4) 16.9 (13.4) 16.8 (13.4) 16.5 (13.3) 15.9 (13.0) 15.0 (12.2) Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 13 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com Table 7. Noise in mVRMS and (mVPP) at AVDD = 5V, AVSS = 0V, and Internal Reference = 2.048V DATA RATE (SPS) PGA SETTING 1 2 4 8 16 32 64 128 5 1.35 (7.78) 0.70 (4.17) 0.35 (2.03) 0.17 (0.95) 0.10 (0.53) 0.06 (0.32) 0.05 (0.31) 0.05 (0.29) 10 1.80 (10.82) 0.88 (5.26) 0.50 (2.75) 0.24 (1.47) 0.13 (0.80) 0.09 (0.49) 0.07 (0.39) 0.07 (0.40) 20 2.62 (14.32) 1.22 (7.05) 0.66 (3.88) 0.35 (2.05) 0.19 (1.09) 0.12 (0.66) 0.10 (0.61) 0.10 (0.55) 40 2.64 (16.29) 1.34 (7.75) 0.69 (4.06) 0.35 (2.07) 0.21 (1.15) 0.15 (0.85) 0.14 (0.81) 0.13 (0.75) 80 3.69 (23.62) 1.82 (10.81) 0.89 (5.48) 0.51 (2.68) 0.30 (1.69) 0.21 (1.32) 0.20 (1.09) 0.18 (0.98) 160 5.70 (35.74) 2.63 (16.90) 1.34 (8.82) 0.68 (4.24) 0.40 (2.65) 0.30 (1.92) 0.28 (1.88) 0.26 (1.57) 320 9.67 (67.44) 4.95 (35.30) 2.59 (17.52) 1.29 (8.86) 0.72 (4.35) 0.49 (3.03) 0.40 (2.44) 0.37 (2.34) 640 13.66 (93.06) 7.04 (45.20) 3.63 (18.73) 1.84 (12.97) 1.02 (6.51) 0.68 (4.20) 0.58 (3.69) 0.53 (3.50) 1000 31.18 (284.59) 16.00 (129.77) 7.58 (61.30) 3.98 (33.04) 2.08 (16.82) 1.16 (9.08) 0.83 (5.42) 0.68 (4.65) 2000 31.42 (273.39) 15.45 (130.68) 8.07 (67.13) 4.06 (36.16) 2.29 (19.22) 1.38 (9.87) 1.06 (6.93) 1.00 (6.48) Table 8. Effective Number of Bits From RMS Noise and (Peak-to-Peak Noise) at AVDD = 5V, AVSS = 0V, and Internal Reference = 2.048V 14 DATA RATE (SPS) PGA SETTING 1 2 4 8 16 32 64 128 5 21.5 (19.0) 21.5 (18.9) 21.5 (18.9) 21.5 (19.0) 21.3 (18.9) 21.0 (18.6) 20.2 (17.7) 19.2 (16.8) 10 21.1 (18.5) 21.1 (18.6) 21.0 (18.5) 21.0 (18.4) 20.9 (18.3) 20.5 (18.0) 19.8 (17.3) 18.7 (16.3) 20 20.6 (18.1) 20.7 (18.1) 20.6 (18.0) 20.5 (17.9) 20.4 (17.8) 20.1 (17.6) 19.2 (16.7) 18.3 (15.8) 40 20.6 (17.9) 20.5 (18.0) 20.5 (17.9) 20.5 (17.9) 20.2 (17.8) 19.7 (17.2) 18.8 (16.3) 17.9 (15.4) 80 20.1 (17.4) 20.1 (17.5) 20.1 (17.5) 20.0 (17.5) 19.7 (17.2) 19.2 (16.6) 18.3 (15.8) 17.5 (15.0) 160 19.5 (16.8) 19.6 (16.9) 19.5 (16.8) 19.5 (16.9) 19.3 (16.6) 18.7 (16.0) 17.8 (15.1) 16.9 (14.3) 320 18.7 (15.9) 18.7 (15.8) 18.6 (15.8) 18.6 (15.8) 18.4 (15.8) 18.0 (15.4) 17.3 (14.7) 16.4 (13.7) 640 18.2 (15.4) 18.1 (15.5) 18.1 (15.7) 18.1 (15.3) 17.9 (15.3) 17.5 (14.9) 16.8 (14.1) 15.9 (13.2) 1000 17.0 (13.8) 17.0 (13.9) 17.0 (14.0) 17.0 (13.9) 16.9 (13.9) 16.8 (13.8) 16.2 (13.5) 15.5 (12.7) 2000 17.0 (13.9) 17.0 (13.9) 17.0 (13.9) 16.9 (13.8) 16.8 (13.7) 16.5 (13.7) 15.9 (13.2) 15.0 (12.3) Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 Table 9. Noise in mVRMS and (mVPP) at AVDD = 3V, AVSS = 0V, and Internal Reference = 2.048V DATA RATE (SPS) PGA SETTING 1 2 4 8 16 32 64 128 5 2.50 (14.24) 1.32 (6.92) 0.67 (3.48) 0.32 (1.68) 0.17 (0.90) 0.09 (0.51) 0.08 (0.42) 0.07 (0.39) 10 3.09 (16.85) 1.69 (9.32) 0.82 (4.68) 0.42 (2.41) 0.23 (1.18) 0.11 (0.63) 0.11 (0.66) 0.10 (0.55) 20 4.55 (24.74) 2.19 (12.82) 1.07 (5.94) 0.55 (3.38) 0.28 (1.66) 0.16 (1.00) 0.15 (0.92) 0.14 (0.87) 40 5.06 (34.59) 2.39 (14.49) 1.27 (7.75) 0.66 (4.01) 0.36 (2.18) 0.21 (1.16) 0.21 (1.27) 0.15 (0.84) 80 6.63 (43.46) 3.28 (20.22) 1.79 (10.64) 0.89 (5.48) 0.47 (2.95) 0.29 (1.63) 0.28 (1.64) 0.21 (1.24) 160 9.75 (68.28) 4.89 (32.19) 2.36 (17.74) 1.26 (9.87) 0.65 (4.77) 0.40 (2.60) 0.40 (2.70) 0.30 (2.12) 320 19.22 (140.06) 9.80 (82.24) 4.81 (32.74) 2.47 (18.59) 1.27 (9.45) 0.71 (5.83) 0.50 (3.36) 0.43 (2.86) 640 27.07 (192.96) 13.54 (100.26) 6.88 (49.07) 3.40 (25.93) 1.76 (12.49) 1.02 (7.49) 0.71 (4.81) 0.60 (4.06) 1000 40.83 (388.28) 20.39 (185.96) 10.39 (89.38) 5.09 (43.28) 2.66 (22.78) 1.45 (11.01) 0.93 (6.74) 0.74 (4.86) 2000 42.06 (322.85) 21.15 (166.75) 10.66 (92.68) 5.61 (44.08) 2.92 (23.06) 1.68 (11.71) 1.19 (8.23) 1.05 (6.97) Table 10. Effective Number of Bits From RMS and (Peak-to-Peak Noise) at AVDD = 3V, AVSS = 0V, and Internal Reference = 2.048V DATA RATE (SPS) PGA SETTING 1 2 4 8 16 32 64 128 5 20.6 (18.1) 20.6 (18.2) 20.5 (18.2) 20.6 (18.2) 20.5 (18.1) 20.4 (17.9) 19.6 (17.2) 18.8 (16.3) 10 20.3 (17.9) 20.2 (17.7) 20.3 (17.7) 20.2 (17.7) 20.1 (17.7) 20.1 (17.6) 19.1 (16.6) 18.3 (15.8) 20 19.8 (17.3) 19.8 (17.3) 19.9 (17.4) 19.8 (17.2) 19.8 (17.2) 19.6 (17.0) 18.7 (16.1) 17.8 (15.2) 40 19.6 (16.9) 19.7 (17.1) 19.6 (17.0) 19.6 (17.0) 19.5 (16.8) 19.2 (16.8) 18.2 (15.6) 17.7 (15.2) 80 19.2 (16.5) 19.3 (16.6) 19.1 (16.6) 19.1 (16.5) 19.0 (16.4) 18.7 (16.3) 17.8 (15.3) 17.2 (14.7) 160 18.7 (15.9) 18.7 (16.0) 18.7 (15.8) 18.6 (15.7) 18.6 (15.7) 18.3 (15.6) 17.3 (14.5) 16.7 (13.9) 320 17.7 (14.8) 17.7 (14.6) 17.7 (14.9) 17.7 (14.7) 17.6 (14.7) 17.5 (14.4) 17.0 (14.2) 16.2 (13.4) 640 17.2 (14.4) 17.2 (14.3) 17.2 (14.3) 17.2 (14.3) 17.1 (14.3) 16.9 (14.1) 16.5 (13.7) 15.7 (12.9) 1000 16.6 (13.4) 16.6 (13.4) 16.6 (13.5) 16.6 (13.5) 16.6 (13.5) 16.4 (13.5) 16.1 (13.2) 15.4 (12.7) 2000 16.6 (13.6) 16.6 (13.6) 16.6 (13.4) 16.5 (13.5) 16.4 (13.4) 16.2 (13.4) 15.7 (12.9) 14.9 (12.2) Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 15 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com TYPICAL CHARACTERISTICS At TA = +25°C, AVDD = 5V, VREF = 2.5V, and AVSS = 0V, unless otherwise noted. NOISE HISTOGRAM PLOT NOISE HISTOGRAM PLOT 1800 1400 1600 1400 1200 1000 800 AVDD = 5V PGA = 32 Data Rate = 20SPS 12k Samples s = 19 1000 800 600 600 400 400 200 200 0 0 -69 -63 -58 -52 -47 -41 -36 -30 -25 -20 -14 -9 -3 1 7 12 18 23 28 34 39 45 50 56 61 67 73 -53 -49 -45 -41 -37 -33 -29 -26 -22 -18 -14 -10 -6 -3 0 4 8 12 16 19 23 27 31 35 39 43 47 Counts 1200 AVDD = 5V PGA = 1 Data Rate = 20SPS 12k Samples s = 13 Counts 1600 1800 (LSB) (LSB) Figure 5. Figure 6. NOISE HISTOGRAM PLOT NOISE HISTOGRAM PLOT 1600 1200 Counts 1000 AVDD = 3.3V PGA = 1 Data Rate = 20SPS 12k Samples s = 18.5 1200 1000 Counts 1400 1400 800 AVDD = 3.3V PGA = 32 Data Rate = 20SPS 12k Samples s = 22 800 600 600 (LSB) RMS NOISE vs INPUT SIGNAL AVDD = 5V PGA = 32 Data Rate = 5SPS 100 60 80 45 25 35 AVDD = 3.3V PGA = 32 Data Rate = 5SPS 0.25 RMS Noise (mV) RMS Noise (mV) 5 RMS NOISE vs INPUT SIGNAL 0.30 0.20 0.15 0.10 0.05 0.20 0.15 0.10 0.05 -80 -60 -40 -20 20 40 60 80 100 0 -100 -80 -60 VIN (% of FSR) Submit Documentation Feedback -40 -20 20 40 60 80 100 VIN (% of FSR) Figure 9. 16 15 Figure 8. 0.30 0 -100 -5 (LSB) Figure 7. 0.25 -15 -80 -25 0 -35 0 -45 200 -60 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 60 70 80 90 100 110 200 -60 400 400 Figure 10. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = 5V, VREF = 2.5V, and AVSS = 0V, unless otherwise noted. OFFSET vs TEMPERATURE OFFSET vs TEMPERATURE 4 8 AVDD = 5V Data Rate = 20SPS 2 1 AVDD = 5V Data Rate = 160SPS 6 Input-Referred Offset (mV) Input-Referred Offset (mV) 3 PGA = 128 0 PGA = 32 -1 PGA = 1 -2 4 2 PGA = 32 0 PGA = 128 -2 -4 PGA = 1 -6 -3 -8 -40 0 -20 20 40 60 80 100 120 -40 0 -20 Temperature (°C) 40 60 80 120 Figure 12. OFFSET vs TEMPERATURE OFFSET vs TEMPERATURE 8 15 AVDD = 5V Data Rate = 640SPS 6 2 Input-Referred Offset (mV) 4 PGA = 32 0 -2 PGA = 128 -4 -6 -8 PGA = 1 -10 AVDD = 5V Data Rate = 2kSPS 10 5 0 PGA = 32 -5 PGA = 128 -10 PGA = 1 -12 -15 -14 -40 -20 0 20 40 60 80 100 120 -40 -20 0 20 40 60 80 100 120 Temperature (°C) Temperature (°C) Figure 13. Figure 14. OFFSET vs TEMPERATURE OFFSET vs TEMPERATURE 4 5 AVDD = 3.3V Data Rate = 20SPS 2 1 0 -1 PGA = 1 PGA = 32 PGA = 128 -2 AVDD = 3.3V Data Rate = 160SPS 4 Input-Referred Offset (mV) 3 Input-Referred Offset (mV) 100 Temperature (°C) Figure 11. Input-Referred Offset (mV) 20 PGA = 1 3 2 PGA = 32 1 0 -1 PGA = 128 -2 -3 -4 -5 -3 -6 -40 -20 0 20 40 60 80 100 120 -40 -20 0 Temperature (°C) Figure 15. 20 40 60 80 100 120 Temperature (°C) Figure 16. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 17 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = 5V, VREF = 2.5V, and AVSS = 0V, unless otherwise noted. OFFSET vs TEMPERATURE OFFSET vs TEMPERATURE 10 8 AVDD = 3.3V Data Rate = 640SPS 6 PGA = 1 4 PGA = 32 2 0 -2 AVDD = 3.3V Data Rate = 2kSPS 6 Input-Referred Offset (mV) Input-Referred Offset (mV) 8 PGA = 128 -4 PGA = 1 4 PGA = 128 2 0 PGA = 32 -2 -4 -6 -6 -8 -40 -20 0 20 40 60 80 100 120 -40 0 -20 20 Temperature (°C) Figure 17. GAIN vs TEMPERATURE 80 120 GAIN vs TEMPERATURE AVDD = 5V Data Rate = 160SPS 0.02 PGA = 1 0.03 PGA = 1 0.01 Gain Error (%) 0.02 0.01 PGA = 32 0 -0.01 -0.02 0 -0.01 PGA = 32 -0.02 PGA = 128 PGA = 128 -0.03 -0.03 AVDD = 5V Data Rate = 20SPS -0.05 -0.04 -40 -20 0 20 40 60 80 100 120 -40 -20 0 Temperature (°C) 20 40 60 80 100 120 Temperature (°C) Figure 19. Figure 20. GAIN vs TEMPERATURE GAIN vs TEMPERATURE 0.03 0.02 AVDD = 5V Data Rate = 2kSPS Data Rate = 640SPS 0.02 0.01 PGA = 1 Gain Error (%) 0.01 Gain Error (%) 100 0.03 0.04 -0.04 60 Figure 18. 0.05 Gain Error (%) 40 Temperature (°C) PGA = 1 0 -0.01 PGA = 128 0 -0.01 PGA = 128 -0.02 -0.02 PGA = 32 -0.03 -0.03 PGA = 32 -0.04 -0.04 -40 -20 0 20 40 60 80 100 120 -40 -20 0 Figure 21. 18 Submit Documentation Feedback 20 40 60 80 100 120 Temperature (°C) Temperature (°C) Figure 22. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = 5V, VREF = 2.5V, and AVSS = 0V, unless otherwise noted. GAIN vs TEMPERATURE GAIN vs TEMPERATURE 0.04 0.04 AVDD = 3.3V Data Rate = 20SPS 0.03 AVDD = 3.3V Data Rate = 160SPS 0.03 PGA = 128 0.02 PGA = 32 Gain Error (%) Gain Error (%) 0.02 0.01 0 PGA = 1 -0.01 PGA = 128 0.01 -0.01 PGA = 32 -0.02 -0.02 -0.03 -0.03 -0.04 PGA = 1 0 -0.04 -40 0 -20 20 40 60 80 100 120 -40 0 -20 20 Temperature (°C) Figure 23. 60 80 100 120 Figure 24. GAIN vs TEMPERATURE GAIN vs TEMPERATURE 0.05 0.05 0.04 AVDD = 3.3V Data Rate = 640SPS PGA = 128 0.04 0.03 0.03 0.02 0.02 Gain Error (%) Gain Error (%) 40 Temperature (°C) 0.01 0 -0.01 -0.02 AVDD = 3.3V Data Rate = 2kSPS PGA = 128 0.01 PGA = 32 0 PGA = 1 -0.01 -0.02 PGA = 1 -0.03 -0.03 PGA = 32 -0.04 -0.04 -0.05 -0.05 -40 -20 0 20 40 60 80 100 120 -40 -20 0 Temperature (°C) 20 40 60 80 100 120 Temperature (°C) Figure 25. Figure 26. ANALOG CURRENT vs DATA RATE DIGITAL CURRENT vs DATA RATE 600 290 550 270 450 AVDD = 5V 400 350 AVDD = 3.3V 300 250 200 Digital Current (mA) Analog Current (mA) 500 250 DVDD = 5V 230 DVDD = 3.3V 210 190 150 170 100 5 10 20 40 80 160 320 640 1000 2000 5 10 20 Data Rate (SPS) Figure 27. 40 80 160 320 640 1000 2000 Data Rate (SPS) Figure 28. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 19 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = 5V, VREF = 2.5V, and AVSS = 0V, unless otherwise noted. ANALOG CURRENT vs TEMPERATURE DIGITAL CURRENT vs TEMPERATURE 800 330 AVDD = 5V DVDD = 5V 2kSPS 700 310 320/640/1kSPS 500 40/80/160SPS 400 5/10/20SPS 300 200 Digital Current (mA) Analog Current (mA) 2kSPS 600 290 320/640/1kSPS 270 250 230 40/80/160SPS 100 210 0 190 5/10/20SPS -40 0 -20 20 40 60 80 100 120 -40 -20 0 20 Temperature (°C) Figure 29. 60 80 100 120 Figure 30. ANALOG CURRENT vs TEMPERATURE DIGITAL CURRENT vs TEMPERATURE 700 310 AVDD = 3.3V 2kSPS DVDD = 3.3V 600 290 500 320/640/1kSPS 400 40/80/160SPS 300 5/10/20SPS 200 Digital Current (mA) 2kSPS Analog Current (mA) 40 Temperature (°C) 270 320/640/1kSPS 250 230 40/80/160SPS 100 210 0 190 5/10/20SPS -40 -20 0 20 40 60 80 100 120 -40 -20 0 Temperature (°C) INTEGRAL NONLINEARITY vs INPUT SIGNAL 80 100 120 INTEGRAL NONLINEARITY vs INPUT SIGNAL 8 PGA = 1 Data Rate = 20SPS 6 PGA = 32 Data Rate = 20SPS 6 4 INL (ppm of FSR) 4 INL (ppm of FSR) 60 Figure 32. 8 -40°C 2 -10°C 0 -2 +25°C -4 2 -10°C 0 -40°C -2 -4 +25°C -6 +105°C -6 +105°C -8 -50 0 50 100 -10 -100 -50 VIN (% of FSR) Submit Documentation Feedback 0 50 100 VIN (% of FSR) Figure 33. 20 40 Temperature (°C) Figure 31. -8 -100 20 Figure 34. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = 5V, VREF = 2.5V, and AVSS = 0V, unless otherwise noted. INTEGRAL NONLINEARITY vs INPUT SIGNAL INTEGRAL NONLINEARITY vs INPUT SIGNAL 8 8 6 -10°C 4 -40°C INL (ppm of FSR) INL (ppm of FSR) 4 -10°C 2 0 -2 +25°C -4 -6 0 -50 +25°C 2 0 -2 -4 +105°C -8 -100 50 PGA = 1 Data Rate = 2kSPS -6 -8 -100 100 50 Figure 36. DATA RATE ERROR vs TEMPERATURE (Using Internal Oscillator) CMRR vs TEMPERATURE 3.0 130 2.5 125 2.0 120 1.5 1.0 CMRR (dB) DVDD = 5V DVDD = 3.3V -0.5 PGA = 32 115 0.5 0 100 VIN (% of FSR) Figure 35. Data Rate Error (%) 0 -50 VIN (% of FSR) -1.0 110 PGA = 128 105 100 95 -1.5 PGA = 1 90 -2.0 85 -2.5 80 -3.0 -40 -20 0 20 40 60 80 100 120 -40 -20 0 20 40 60 80 100 120 Temperature (°C) Temperature (°C) Figure 37. Figure 38. INTERNAL VREF vs TEMPERATURE IDAC LINE REGULATION 2.050 1.002 14 Units 1.001 Normalized Output Current Output Voltage (V) +105°C -40°C PGA = 128 Data Rate = 20SPS 6 2.049 2.048 2.047 1.000 0.999 50mA 100mA 0.998 0.997 500mA 0.996 250mA 0.995 750mA 0.994 0.993 1mA 0.992 2.046 IDAC Current Settings 1.5mA 0.991 -40 -20 0 20 40 60 80 100 120 2.0 2.5 3.0 Temperature (°C) Figure 39. 3.5 4.0 4.5 5.0 5.5 6.0 AVDD (V) Figure 40. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 21 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, AVDD = 5V, VREF = 2.5V, and AVSS = 0V, unless otherwise noted. IDAC DRIFT POWER-SUPPLY REJECTION vs GAIN 0.004 8 1.5mA Setting, 10 Units Power-Supply Rejection (mV/V) IEXC1 - IEXC2 (mA) 0.003 0.002 0.001 0 -0.001 -0.002 -0.003 -0.004 7 2000SPS 6 5 320/640/1000SPS 4 3 40/80/160SPS 2 5/10/20SPS 1 0 -40 -20 0 20 40 60 80 100 120 1 2 4 8 Temperature (°C) 16 32 64 128 Gain Figure 41. Figure 42. INTERNAL VREF INITIAL ACCURACY HISTOGRAM IDAC INITIAL ACCURACY HISTOGRAM 700 200 2280 Units 180 600 2280 Units 140 400 120 Counts 300 100 80 60 200 40 100 20 0 2.25 2.50 2.00 1.50 1.75 1.00 1.25 0.50 0.75 0 Initial Accuracy (V) 0.25 -0.50 -0.25 -1.00 -1.25 2.0485 2.0484 2.0483 2.0482 2.0481 2.0480 2.0479 2.0478 2.0477 2.0476 2.0475 0 -0.75 Counts 160 500 Initial Accuracy (%) Figure 43. Figure 44. IDAC MISMATCH HISTOGRAM 350 2280 Units 300 Counts 250 200 150 100 50 0.6 0.5 0.4 0.3 0.2 0 0.1 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 0 Initial Accuracy (%) Figure 45. 22 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 GENERAL DESCRIPTION OVERVIEW The ADS1247 and ADS1248 also include a flexible input multiplexer with system monitoring capability and general-purpose I/O settings, a very low-drift voltage reference, and two matched current sources for sensor excitation. Figure 46 and Figure 47 show the various functions incorporated in each device. The ADS1246, ADS1247 and ADS1248 are highly integrated 24-bit data converters. They include a low-noise, high-impedance programmable gain amplifier (PGA), a delta-sigma (ΔΣ) ADC with an adjustable single-cycle settling digital filter, internal oscillator, and a simple but flexible SPI-compatible serial interface. REFP AVDD REFN DVDD Burnout Detect ADS1246 VBIAS SCLK DIN AIN0 AIN1 Input Mux 3rd Order DS Modulator PGA Adjustable Digital Filter Serial Interface and Control DRDY DOUT/DRDY CS START RESET Internal Oscillator Burnout Detect AVSS DGND CLK Figure 46. ADS1246 Diagram AVDD REFP0/ REFN0/ ADS1248 Only GPIO0 GPIO1 REFP1 REFN1 VREFOUT VREFCOM Burnout Detect Voltage Reference VREF Mux VBIAS DVDD ADS1247 ADS1248 GPIO AIN0/IEXC AIN1/IEXC SCLK System Monitor AIN2/IEXC/GPIO2 AIN3/IEXC/GPIO3 Input Mux AIN4/IEXC/GPIO4 AIN5/IEXC/GPIO5 PGA DIN 3rd Order DS Modulator Dual Current DACs AIN6/IEXC/GPIO6 AIN7/IEXC/GPIO7 ADS1248 Only Adjustable Digital Filter Serial Interface and Control DRDY DOUT/DRDY CS START RESET Internal Oscillator Burnout Detect AVSS IEXC1 IEXC2 CLK DGND ADS1248 Only Figure 47. ADS1247, ADS1248 Diagram Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 23 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com ADC INPUT AND MULTIPLEXER Any analog input pin can be selected as the positive input or negative input through the MUX0 register. The ADS1246/7/8 have a true fully differential mode, meaning that the input signal range can be from –2.5V to +2.5V (when AVDD = 2.5V and AVSS = –2.5V). The ADS1246/7/8 ADC measures the input signal through the onboard PGA. All analog inputs are connected to the internal AINP or AINN analog inputs through the analog multiplexer. A block diagram of the analog input multiplexer is shown in Figure 48. The input multiplexer connects to eight (ADS1248), four (ADS1247), or two (ADS1246) analog inputs that can be configured as single-ended inputs, differential inputs, or in a combination of single-ended and differential inputs. The multiplexer also allows the on-chip excitation current and/or bias voltage to be selected to a specific channel. AVDD Through the input multiplexer, the ambient temperature (internal temperature sensor), AVDD, DVDD, and external reference can all be selected for measurement. Refer to the System Monitor section for details. On the ADS1247 and ADS1248, the analog inputs can also be configured as general-purpose inputs/outputs (GPIOs). See the General-Purpose Digital I/O section for more details. AVDD IDAC2 IDAC1 System Monitors AVSS AVDD VBIAS AVDD AVDD AIN0 AVSS AVDD VBIAS Temperature Diode VREFP VREFN AIN1 ADS1247/48 Only AVSS AVDD VREFP1/4 VBIAS VREFN1/4 VREFP0/4 AIN2 AVSS AVDD VREFN0/4 VBIAS AVDD/4 AIN3 AVSS/4 DVDD/4 ADS1248 Only AVSS AVDD DGND/4 VBIAS AIN4 AVDD AVSS AVDD Burnout Current Source (0.5mA, 2mA, 10mA) VBIAS AIN5 AINP AVSS AVDD VBIAS AVSS AVDD VBIAS AINN PGA To ADC AIN6 AIN7 Burnout Current Source (0.5mA, 2mA, 10mA) AVSS Figure 48. Analog Input Multiplexer Circuit 24 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 ESD diodes protect the ADC inputs. To prevent these diodes from turning on, make sure the voltages on the input pins do not go below AVSS by more than 100mV, and do not exceed AVDD by more than 100mV, as shown in Equation 2. Note that the same caution is true if the inputs are configured to be GPIOs. AVSS – 100mV < (AINX) < AVDD + 100mV (2) Settling Time for Channel Multiplexing The ADS1246/7/8 is a true single-cycle settling ΔΣ converter. The first data available after the start of a conversion are fully settled and valid for use. The time required to settle is roughly equal to the inverse of the data rate. The exact time depends on the specific data rate and the operation that resulted in the start of a conversion; see Table 20 for specific values. VOLTAGE REFERENCE INPUT The voltage reference for the ADS1246/7/8 is the differential voltage between REFP and REFN: VREF = VREFP – VREFN In the case of the ADS1246, these pins are dedicated inputs. For the ADS1247 and ADS1248, there is a multiplexer that selects the reference inputs, as shown in Figure 49. The reference input uses a buffer to increase the input impedance. As with the analog inputs, REFP0 and REFN0 can be configured as digital I/Os on the ADS1247/8. ADS1248 Only REFP1 REFN1 REFP0 REFN0 VREFOUT VREFCOM ANALOG INPUT IMPEDANCE The ADS1246/7/8 inputs are buffered through a high-impedance PGA before they reach the ΔΣ modulator. For the majority of applications, the input current leakage is minimal and can be neglected. However, because the PGA is chopper-stabilized for noise and offset performance, the input impedance is best described as small absolute input current. The absolute current leakage for selected channels is approximately proportional to the selected modulator clock. Table 11 shows the typical values for these currents with a differential voltage coefficient and the corresponding input impedances over data rate. Internal Voltage Reference Reference Multiplexer REFP REFN ADC Figure 49. Reference Input Multiplexer The reference input circuit has ESD diodes to protect the inputs. To prevent the diodes from turning on, make sure the voltage on the reference input pin is not less than AVSS – 100mV, and does not exceed AVDD + 100mV, as shown in Equation 3: AVSS – 100mV < (VREFP or VREFN) < AVDD + 100mV (3) Table 11. Typical Values for Analog Input Current Over Data Rate (1) (1) CONDITION ABSOLUTE INPUT CURRENT EFFECTIVE INPUT IMPEDANCE DR = 5SPS, 10SPS, 20SPS ± (0.5nA + 0.1nA/V) 5000MΩ DR = 40SPS, 80SPS, 160SPS ± (2nA + 0.5nA/V) 1200MΩ DR = 320SPS, 640SPS, 1kSPS ± (4nA + 1nA/V) 600MΩ DR = 2kSPS ± (8nA + 2nA/V) 300MΩ Input current with VCM = 2.5V. TA = +25°C, AVDD = 5V, and AVSS = 0V. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 25 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com LOW-NOISE PGA MODULATOR The ADS1246/7/8 feature a low-drift, low-noise, high input impedance programmable gain amplifier (PGA). The PGA can be set to gain of 1, 2, 4, 8, 16, 32, 64, or 128 by register SYS0. A simplified diagram of the PGA is shown in Figure 50. A third-order modulator is used in the ADS1246/7/8. The modulator converts the analog input voltage into a pulse code modulated (PCM) data stream. To save power, the modulator clock runs from 32kHz up to 512kHz for different data rates, as shown in Table 12. The PGA consists of two chopper-stabilized amplifiers (A1 and A2) and a resistor feedback network that sets the gain of the PGA. The PGA input is equipped with an electromagnetic interference (EMI) filter, as shown in Figure 50. Note that as with any PGA, it is necessary to ensure that the input voltage stays within the specified common-mode input range specified in the Electrical Characteristics. The common-mode input (VCMI) must be within the range shown in Equation 4: Table 12. Modulator Clock Frequency for Different Data Rates ( AVSS + 0.1V + ) ( ) (VIN)(Gain) (V )(Gain) £ VCMI £ AVDD - 0.1V - IN 2 2 (4) 454W AINP 7.5pF A1 R 7.5pF C R ADC fMOD (kHz) 5, 10, 20 32 40, 80, 160 128 320, 640, 1000 256 2000 512 DIGITAL FILTER The ADS1246/7/8 use linear-phase finite impulse response (FIR) digital filters that can be adjusted for different output data rates. The digital filter always settles in a single cycle. Table 13 shows the exact data rates when an external oscillator equal to 4.096MHz is used. Also shown is the signal –3dB bandwidth, and the 50Hz and 60Hz attenuation. For good 50Hz or 60Hz rejection, use a data rate of 20SPS or slower. The frequency responses of the digital filter are shown in Figure 51 to Figure 61. Figure 54 shows a detailed view of the filter frequency response from 48Hz to 62Hz for a 20SPS data rate. All filter plots are generated with 4.096MHz external clock. 7.5pF A2 454W DATA RATE (SPS) AINN 7.5pF Figure 50. Simplified Diagram of the PGA Table 13. Digital Filter Specifications (1) ATTENUATION NOMINAL DATA RATE ACTUAL DATA RATE –3dB BANDWIDTH fIN = 50Hz ±0.3Hz fIN = 60Hz ±0.3Hz fIN = 50Hz ±1Hz fIN = 60Hz ±1Hz 5SPS 5.018SPS 2.26Hz –106dB –74dB –81dB –69dB 10SPS 10.037SPS 4.76Hz –106dB –74dB –80dB –69dB 20SPS 20.075SPS 14.8Hz –71dB –74dB –66dB –68dB 40SPS 40.15SPS 9.03Hz (1) 26 80SPS 80.301SPS 19.8Hz 160SPS 160.6SPS 118Hz 320SPS 321.608SPS 154Hz 495Hz 640SPS 643.21SPS 1000SPS 1000SPS 732Hz 2000SPS 2000SPS 1465Hz Values shown for fOSC = 4.096MHz. Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 0 -60 -20 -70 Magnitude (dB) Magnitude (dB) www.ti.com -40 -60 -80 -80 -90 -100 -110 -100 -120 -120 0 20 40 60 80 48 100 120 140 160 180 200 50 Figure 51. Filter Profile with Data Rate = 5SPS 52 54 56 58 60 62 Frequency (Hz) Frequency (Hz) Figure 54. Detailed View of Filter Profile with Data Rate = 20SPS between 48Hz and 62Hz 0 0 -20 Magnitude (dB) Magnitude (dB) -20 -40 -60 -80 -40 -60 -80 -100 -100 -120 0 20 40 60 80 100 120 140 160 180 200 -120 0 Frequency (Hz) 200 400 600 800 1000 1200 1400 1600 1800 2000 Frequency (Hz) Figure 52. Filter Profile with Data Rate = 10SPS Figure 55. Filter Profile with Data Rate = 40SPS 0 0 -20 -40 Gain (dB) Magnitude (dB) -20 -40 -60 -80 -60 -80 -100 -100 -120 0 20 40 60 80 100 120 140 160 180 200 Frequency (Hz) -120 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Frequency (Hz) Figure 53. Filter Profile with Data Rate = 20SPS Figure 56. Filter Profile with Data Rate = 80SPS Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 27 ADS1246 ADS1247 ADS1248 www.ti.com 0 0 -20 -20 Magnitude (dB) Magnitude (dB) SBAS426D – AUGUST 2008 – REVISED MARCH 2010 -40 -60 -80 -100 -40 -60 -80 -100 -120 -120 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 1 2 3 Frequency (Hz) 0 0 -20 -20 -40 -60 -80 -100 6 7 8 9 10 -40 -60 -80 -100 -120 -120 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 2 4 Frequency (Hz) Figure 58. Filter Profile with Data Rate = 320SPS 6 8 10 12 14 16 18 20 Frequency (kHz) Figure 61. Filter Profile with Data Rate = 2kSPS CLOCK SOURCE 0 The ADS1246/7/8 can use either the internal oscillator or an external clock. Connect the CLK pin to DGND before power-on or reset to activate the internal oscillator. Connecting an external clock to the CLK pin at any time deactivates the internal oscillator, with the device then operating on the external clock. After the device switches to the external clock, it cannot be switched back to the internal oscillator without cycling the power supplies or resetting the device. -20 Magnitude (dB) 5 Figure 60. Filter Profile with Data Rate = 1kSPS Magnitude (dB) Magnitude (dB) Figure 57. Filter Profile with Data Rate = 160SPS 4 Frequency (kHz) -40 -60 -80 -100 -120 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Frequency (Hz) Figure 59. Filter Profile with Data Rate = 640SPS 28 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 INTERNAL VOLTAGE REFERENCE EXCITATION CURRENT SOURCE DACS The ADS1247/8 includes an onboard voltage reference with a low temperature coefficient. The output of the voltage reference is 2.048V with the capability of both sourcing and sinking up to 10mA of current. The ADS1247/8 provide two matched excitation current sources for RTD applications. For three- or four-wire RTD applications, the matched current sources can be used to cancel the errors caused by sensor lead resistance. The output current of the current source DACs can be programmed to 50mA, 100mA, 250mA, 500mA, 750mA, 1000mA, or 1500mA. The voltage reference must have a capacitor connected between VREFOUT and VREFCOM. The value of the capacitance should be in the range of 1mF to 47mF. Large values provide more filtering of the reference; however, the turn-on time increases with capacitance, as shown in Table 14. For stability reasons, VREFCOM must have a path with an impedance less than 10Ω to ac ground nodes, such as GND (for a 0V to 5V analog power supply), or AVSS (for a ±2.5V analog power supply). In case this impedance is higher than 10Ω, a capacitor of at least 0.1mF should be connected between VREFCOM and an ac ground node (for example, GND). Note that because it takes time for the voltage reference to settle to the final voltage, care must be taken when the device is turned off between conversions. Allow adequate time for the internal reference to fully settle. Table 14. Internal Reference Settling Time VREFOUT CAPACITOR 1mF 4.7mF 47mF SETTLING ERROR TIME TO REACH THE SETTLING ERROR ±0.5% 70ms ±0.1% 110ms ±0.5% 290ms ±0.1% 375ms ±0.5% 2.2ms ±0.1% 2.4ms The onboard reference is controlled by the registers; by default, it is off after startup (see the ADS1247/48 Detailed Register Definitions section for more details). Therefore, the internal reference must first be turned on and then connected via the internal reference multiplexer. Because the onboard reference is used to generate the current reference for the excitation current sources, it must be turned on before the excitation currents become available. The two matched current sources can be connected to dedicated current output pins IOUT1 and IOUT2 (ADS1248 only), or to any AIN pin (ADS1247/8); refer to the ADS1247/48 Detailed Register Definitions section for more information. It is possible to connect both current sources to the same pin. Note that the internal reference must be turned on and properly compensated when using the excitation current source DACs. SENSOR DETECTION The ADS1246/7/8 provide a selectable current (0.5mA, 2mA, or 10mA) to help detect a possible sensor malfunction. When enabled, two burnout current sources flow through the selected pair of analog inputs to the sensor. One sources the current to the positive input channel, and the other sinks the same current from the negative input channel. When the burnout current sources are enabled, a full-scale reading may indicate an open circuit in the front-end sensor, or that the sensor is overloaded. It may also indicate that the reference voltage is absent. A near-zero reading may indicate a short-circuit in the sensor. BIAS VOLTAGE GENERATION A selectable bias voltage is provided for use with ungrounded thermocouples. The bias voltage is (AVDD + AVSS)/2 and can applied to any analog input channel through internal input multiplexer. The bias voltage turn-on times for different sensor capacitances are listed in Table 15. Table 15. Bias Voltage Settling Time SENSOR CAPACITANCE SETTLING TIME 0.1mF 220ms 1mF 2.2ms 10mF 22ms 200mF 450ms Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 29 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com GENERAL-PURPOSE DIGITAL I/O Power-Supply Monitor The ADS1248 has eight pins and the ADS1247 has four pins that serve a dual purpose as either analog inputs or general-purpose digital inputs/outputs (GPIOs). The system monitor can measure the analog or digital power supply. When measuring the power supply, the resulting conversion is approximately 1/4 of the actual power supply voltage. Figure 62 shows a diagram of how these functions are combined onto a single pin. Note that when the pin is configured as a GPIO, the corresponding logic is powered from AVDD and AVSS. When the ADS1247/8 are operated with bipolar analog supplies, the GPIO outputs bipolar voltages. Care must be taken loading the GPIO pins when used as outputs because large currents can cause droop or noise on the analog supplies. Conversion Result = (VSP/4)/VREF IOCFG IODIR REFx0/GPIOx AINx/GPIOx DIO WRITE To Analog Mux DIO READ Figure 62. Analog/Data Interface Pin SYSTEM MONITOR The ADS1247 and ADS1248 provide a system monitor function. This function can measure the analog power supply, digital power supply, external voltage reference, or ambient temperature. Note that the system monitor function provides a coarse result. When the system monitor is enabled, the analog inputs are disconnected. 30 Submit Documentation Feedback (5) Where VSP is the selected supply to be measured. External Voltage Reference Monitor The ADS1246/7/8 can be selected to measure the external voltage reference. In this configuration, the monitored external voltage reference is connected to the analog input. The result (conversion code) is approximately 1/4 of the actual reference voltage. Conversion Result = (VREX/4)/VREF Where VREX monitored. is the external (6) reference to be NOTE: The internal reference voltage must be enabled when measuring an external voltage reference using the system monitor. Ambient Temperature Monitor On-chip diodes provide temperature-sensing capability. When selecting the temperature monitor function, the anodes of two diodes are connected to the ADC. Typically, the difference in diode voltage is 118mV at +25°C with a temperature coefficient of 405mV/°C. Note that when the onboard temperature monitor is selected, the PGA is automatically set to '1'. However, the PGA register bits in are not affected and the PGA returns to its set value when the temperature monitor is turned off. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 CALIBRATION The conversion data are scaled by offset and gain registers before yielding the final output code. As shown in Figure 63, the output of the digital filter is first subtracted by the offset register (OSC) and then multiplied by the full-scale register (FSC). A digital clipping circuit ensures that the output code does not exceed 24 bits. Equation 7 shows the scaling. + S ´ OFC Register FSC Register 400000h ADC - Output Data Clipped to 24 Bits Final Output Figure 63. Calibration Block Diagram FSC[2:0] Final Output Data = (Input - OFC[2:0]) ´ 400000h (7) The values of the offset and full-scale registers are set by writing to them directly, or they are set automatically by calibration commands. Offset Calibration Register: OFC[2:0] The offset calibration is a 24-bit word, composed of three 8-bit registers. The offset is in twos complement format with a maximum positive value of 7FFFFFh and a maximum negative value of 800000h. This value is subtracted from the conversion data. A register value of 000000h provides no offset correction. Note that while the offset calibration register value can correct offsets ranging from –FS to +FS (as shown in Table 16), make sure to avoid overloading the analog inputs. Table 16. Final Output Code versus Offset Calibration Register Setting full-scale calibration register can correct gain errors > 1 (with gain scaling < 1), make sure to avoid overloading the analog inputs. The default or reset value of FSC depends on the PGA setting. A different factory-trimmed FSC Reset value is stored for each PGA setting which provides outstanding gain accuracy over all the ADS1246/7/8 input ranges. Note: The factory-trimmed FSC reset value loads automatically loaded whenever the PGA setting changes. Table 17. Gain Correction Factor versus Full-Scale Calibration Register Setting FULL-SCALE REGISTER GAIN SCALING 800000h 2.0 400000h 1.0 200000h 0.5 000000h 0 Calibration Commands The ADS1246/7/8 provide commands for three types of calibration: system gain calibration, system offset calibration and self offset calibration. Where absolute accuracy is needed, it is recommended that calibration be performed after power on, a change in temperature, a change of PGA and in some cases a change in channel. At the completion of calibration, the DRDY signal goes low indicating the calibration is finished. The first data after calibration are always valid. If the START pin is taken low or a SLEEP command is issued after any calibration command, the devices goes to sleep after completing calibration. System Gain Calibration System gain calibration corrects for gain error in the signal path. The system gain calibration is initiated by sending the SYSGCAL command while applying a full-scale input to the selected analog inputs. Afterwards the full-scale calibration register (FSC) is updated. When a system gain calibration command is issued, the ADS1246/7/8 stop the current conversion and start the calibration procedure immediately. OFFSET REGISTER FINAL OUTPUT CODE WITH VIN = 0 7FFFFFh 8000000h 000001h FFFFFFh 000000h 000000h System Offset and Self Offset Calibration FFFFFFh 000001h 8000000h 7FFFFFh System offset calibration corrects both internal and external offset errors. The system offset calibration is initiated by sending the SYSGOCAL command while applying a zero differential input (VIN = 0) to the selected analog inputs. The self offset calibration is initiated by sending the SELFOCAL command. During self offset calibration, the selected inputs are disconnected from the internal circuitry and a zero differential signal is applied internally. With both offset 1. Excludes effects of noise and inherent offset errors. Full-Scale Calibration Register: FSC[2:0] The full-scale or gain calibration is a 24-bit word composed of three 8-bit registers. The full-scale calibration value is 24-bit, straight binary, normalized to 1.0 at code 400000h. Table 17 summarizes the scaling of the full-scale register. Note that while the Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 31 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com calibrations the offset calibration register (OFC) is updated afterwards. When either offset calibration command is issued, the ADS1246/7/8 stop the current conversion and start the calibration procedure immediately. ADC SLEEP MODE Calibration Timing During sleep mode, the internal reference status depends on the setting of the VREFCON bits in the MUX1 register; see the Register Descriptions section for details. When calibration is initiated, the device performs 16 consecutive data conversions and averages the results to calculate the calibration value. This provides a more accurate calibration value. The time required for calibration is shown in Table 18 and can be calculated using Equation 8: 50 32 16 + + Calibration Time = fOSC fMOD fDATA (8) Table 18. Calibration Time versus Data Rate DATA RATE (SPS) CALIBRATION TIME (ms) 5 3201.01 10 1601.01 20 801.012 40 400.26 80 200.26 160 100.14 320 50.14 640 25.14 1000 16.14 2000 8.07 1. For fOSC = 4.096MHz. ADC POWER-UP When DVDD is pulled up, the internal power-on reset module generates a pulse that resets all digital circuitry. All the digital circuits are held in a reset state for 216 system clocks to allow the analog circuits and the internal digital power supply to settle. SPI communication cannot occur until the internal reset is released. 32 Submit Documentation Feedback Power consumption can be dramatically reduced by placing the ADS1246/7/8 into sleep mode. There are two ways to put the device into sleep mode: the sleep command (SLEEP) and through the START pin. ADC CONTROL ADC Conversion Control The START pin provides easy and precise control of conversions. Pulse the START pin high to begin a conversion, as shown in Figure 64 and Table 19. The conversion completion is indicated by the DOUT/DRDY pin going low. When the conversion completes, the ADS1246/7/8 automatically shuts down to save power. During shutdown, the conversion result can be retrieved; however, START must be taken high before communicating with the configuration registers. The device stays shut down until the START pin is once again taken high to begin a new conversion. When the START pin is taken back high again, the decimation filter is held in a reset state for 32 modulator clock cycles internally to allow the analog circuits to settle. The ADS1246/7/8 can be configured to convert continuously by holding the START pin high, as shown in Figure 65. With the START pin held high, the ADC converts the selected input channels continuously. This configuration continues until the START pin is taken low. The START pin can also be used to perform the synchronized measurement for the multi-channel applications by pulsing the START pin. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 tSTART START tCONV DOUT/DRDY 1 2 3 24 SCLK DRDY ADS1246/47/48 Status Shutdown Converting Figure 64. Timing for Single Conversion Using START Pin Table 19. START Pin Conversion Times for Figure 64 SYMBOL tCONV DESCRIPTION DATA RATE (SPS) VALUE UNIT 5 200.295 ms 10 100.644 ms 20 50.825 ms 40 25.169 ms Time from START pulse to DRDY and DOUT/DRDY going low START Data Ready 80 12.716 ms 160 6.489 ms 320 3.247 ms 640 1.692 ms 1000 1.138 ms 2000 0.575 ms Data Ready Data Ready DOUT/DRDY ADS1246/47/48 Status Converting Converting Converting Converting NOTE: SCLK held low in this example. Figure 65. Timing for Conversion with START Pin High Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 33 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 RESET When the RESET pin goes low, the device is immediately reset. All the registers are restored to default values. The device stays in reset mode as long as the RESET pin stays low. When it goes high, the ADC comes out of reset mode and is able to convert data. After the RESET pin goes high, and when the system clock frequency is 4.096MHz, the digital filter and the registers are held in a reset state for 0.6ms when fOSC = 4.096MHz. Therefore, valid SPI communication can only be resumed 0.6ms after the RESET pin goes high; see Figure 4. When the RESET pin goes low, the clock selection is reset to the internal oscillator. Channel Cycling and Overload Recovery When cycling through channels, care must be taken when configuring the ADS1246/7/8 to ensure that settling occurs within one cycle. For setups that simply cycle through MUX channels, but do not change PGA and data rate settings, simply changing the MUX0 register is sufficient. However, when changing PGA and data rate settings it is important to ensure that an overloaded condition cannot occur during the transmission. When configuration data are transferred to the ADS1246/7/8, new settings become active at the end of each byte sent. Therefore, a brief overload condition can occur during the transmission of configuration data after the completion of the MUX0 byte and before completion of the SYS0 byte. This temporary overload can result in intermittent incorrect readings. To ensure that an overload does not occur, it may be necessary to split the communication into two separate communications allowing the change of the SYS0 register before the change of the MUX0 register. 34 Submit Documentation Feedback www.ti.com In the event of an overloaded state, care must also be taken to ensure single cycle settling into the next cycle. Because the ADS1246/7/8 implement a chopper-stabilized PGA, changing data rates during an overload state can cause the chopper to become unstable. This instability results in slow settling time. To prevent this slow settling, always change the PGA setting or MUX setting to a non-overloaded state before changing the data rate. Digital Filter Reset Operation Apart from the RESET command and the RESET pin, the digital filter is reset automatically when either a write operation to the MUX0, VBIAS, MUX1, or SYS0 registers is performed, when a SYNC command is issued, or the START pin is taken high. The filter is reset two system clocks after the last bit of the SYNC command is sent. The reset pulse created internally lasts for two multiplier clock cycles. If any write operation takes place in the MUX0 register, the filter is reset regardless of whether the value changed or not. Internally, the filter pulse lasts for two system clock periods. If any write activity takes place in the VBIAS, MUX1, or SYS0 registers, the filter is reset as well, regardless of whether the value changed or not. The reset pulse lasts for 32 modulator clocks after the write operation. If there are multiple write operations, the resulting reset pulse may be viewed as the ANDed result of the different active low pulses created individually by each action. Table 20 shows the conversion time after a filter reset. Note that this time depends on the operation initiating the reset. Also, the first conversion after a filter reset has a slightly different time than the second and subsequent conversions. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 Table 20. Data Conversion Time FIRST DATA CONVERSION TIME AFTER FILTER RESET SYNC COMMAND, MUX0 REGISTER WRITE (ms) (1) NO. OF SYSTEM CLOCK CYCLES 5.019 199.264 10 10.038 20 SECOND AND SUBSEQUENT CONVERSION TIME AFTER FILTER RESET (ms) (1) NO. OF SYSTEM CLOCK CYCLES (ms) NO. OF SYSTEM CLOCK CYCLES 816188 200.260 820265 199.250 816128 99.639 408124 100.635 412201 99.625 408064 20.075 49.827 204092 50.822 208169 49.812 204032 40 40.151 24.920 102076 25.172 103106 24.906 102016 80 80.301 12.467 51068 12.719 52098 12.453 51008 160 160.602 6.241 25564 6.492 26594 6.226 25504 320 321.608 3.124 12796 3.250 13314 3.109 12736 640 643.216 1.569 6428 1.695 6946 1.554 6368 1000 1000.000 1.014 4156 1.141 4674 1.000 4096 2000 2000.000 0.514 2108 0.578 2370 0.500 2048 NOMINAL DATA RATE (SPS) EXACT DATA RATE (SPS) 5 (1) HARDWARE RESET, RESET COMMAND, START PIN HIGH, WAKEUP COMMAND, VBIAS, MUX1, or SYS0 REGISTER WRITE For fOSC = 4.096MHz. Data Format The ADS1246/7/8 output 24 bits of data in binary twos complement format. The least significant bit (LSB) has a weight of (VREF/PGA)/(223 – 1). The positive full-scale input produces an output code of 7FFFFFh and the negative full-scale input produces an output code of 800000h. The output clips at these codes for signals exceeding full-scale. Table 21 summarizes the ideal output codes for different input signals. Table 21. Ideal Output Code vs Input Signal INPUT SIGNAL, VIN (AINP – AINN) IDEAL OUTPUT CODE ≥ +VREF/PGA 7FFFFFh (+VREF/PGA)/(223 – 1) 000001h 0 000000h 23 (–VREF/PGA)/(2 – 1) ≤ –(VREF/PGA) × (223/223 – 1) FFFFFFh 800000h 1. Excludes effects of noise, linearity, offset, and gain errors. Digital Interface The ADS1246/7/8 provide a standard SPI serial communication interface plus a data ready signal (DRDY). Communication is full-duplex with the exception of a few limitations in regards to the RREG command and the RDATA command. These limitations are explained in detail in the SPI Commands section of this data sheet. For the basic serial interface timing characteristics, see Figure 1 and Figure 2 of this datasheet. CS The chip select pin (active low). The CS pin activates SPI communication. CS must be low before data transactions and must stay low for the entire SPI communication period. When CS is high, the DOUT/DRDY pin enters a high-impedance state. Therefore, reading and writing to the serial interface are ignored and the serial interface is reset. DRDY pin operation is independent of CS. Taking CS high deactivates only the SPI communication with the device. Data conversion continues and the DRDY signal can be monitored to check if a new conversion result is ready. A master device monitoring the DRDY signal can select the appropriate slave device by pulling the CS pin low. SCLK The serial clock signal. SCLK provides the clock for serial communication. It is a Schmitt-trigger input, but it is highly recommended that SCLK be kept as clean as possible to prevent glitches from inadvertently shifting the data. Data are shifted into DIN on the falling edge of SCLK and shifted out of DOUT on the rising edge of SCLK. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 35 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com DIN The data input pin. DIN is used along with SCLK to send data to the device. Data on DIN are shifted into the device on the falling edge of SCLK. The communication of this device is full-duplex in nature. The device monitors commands shifted in even when data are being shifted out. Data that are present in the output shift register are shifted out when sending in a command. Therefore, it is important to make sure that whatever is being sent on the DIN pin is valid when shifting out data. When no command is to be sent to the device when reading out data, the NOP command should be sent on DIN. DRDY The data ready pin. The DRDY pin goes low to indicate a new conversion is complete, and the conversion result is stored in the conversion result buffer. The SPI clock must be low in a short time frame around the DRDY low transition (see Figure 2) so that the conversion result is loaded into both the result buffer and the output shift register. Therefore, no commands should be issued during this time frame if the conversion result is to be read out later. This constraint applies only when CS is asserted. When CS is not asserted, SPI communication with other devices on the SPI bus does not affect loading of the conversion result. After the DRDY pin goes low, it is forced high on the first falling edge of SCLK (so that the DRDY pin can be polled for '0' instead of waiting for a falling edge). If the DRDY pin is not taken high after it falls low, a short high pulse is created on it to indicate the next data are ready. When the DRDY MODE bit is set to '0', this pin functions as DOUT only. Data are clocked out at rising edge of SCLK, MSB first (see Figure 66). When the DRDY MODE bit is set to '1', this pin functions as both DOUT and DRDY. Data are shifted out from this pin, MSB first, at the rising edge of SCLK. This combined pin allows for the same control but with fewer pins. When the DRDY MODE bit is enabled and a new conversion is complete, DOUT/DRDY goes low if it is high. If it is already low, then DOUT/DRDY goes high and then goes low (see Figure 67). Similar to the DRDY pin, a falling edge on the DOUT/DRDY pin signals that a new conversion result is ready. After DOUT/DRDY goes low, the data can be clocked out by providing 24 SCLKs. In order to force DOUT/DRDY high (so that DOUT/DRDY can be polled for a '0' instead of waiting for a falling edge), a no operation command (NOP) or any other command that does not load the data output register can be sent after reading out the data. Because SCLKs can only be sent in multiples of eight, a NOP can be sent to force DOUT/DRDY high if no other command is pending. The DOUT/DRDY pin goes high after the first rising edge of SCLK after reading the conversion result completely (see Figure 68). The same condition also applies after an RREG command. After all the register bits have been read out, the rising edge of SCLK forces DOUT/DRDY high. Figure 69 illustrates an example where sending four NOP commands after an RREG command forces the DOUT/DRDY pin high. DOUT/DRDY This pin has two modes: data out (DOUT) only, or data out (DOUT) combined with data ready (DRDY). The DRDY MODE bit determines the function of this pin. In either mode, the DOUT/DRDY pin goes to a high-impedance state when CS is taken high. SCLK DOUT/DRDY(1) 1 2 D[23] D[22] 3 D[21] 22 D[2] 23 D[1] 24 1 2 8 D[0] DRDY (1) CS tied low. Figure 66. Data Retrieval with the DRDY MODE Bit = 0 (Disabled) 36 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 SCLK DOUT/DRDY(1) 1 2 3 22 D[23] D[22] D[21] D[2] 23 D[1] 24 D[0] 1 2 D[23] D[22] NOP DIN 24 D[0] NOP DRDY (1) CS tied low. Figure 67. Data Retrieval with the DRDY MODE Bit = 1 (Enabled) SCLK DOUT/DRDY(1) DIN 1 2 3 22 D[23] D[22] D[21] D[2] 23 D[1] 24 1 2 8 D[0] NOP 1 2 D[23] D[22] NOP 24 D[0] NOP DRDY (1) DRDY MODE bit enabled, CS tied low. Figure 68. DOUT/DRDY Forced High After Retrieving the Conversion Result 1 2 7 8 1 2 7 8 SCLK DOUT/DRDY(1) reg[7] DIN (1) reg[1] reg[0] NOP NOP DRDY MODE bit enabled, CS tied low. Figure 69. DOUT/DRDY Forced High After Reading Register Data The DRDY MODE bit modifies only the DOUT/DRDY pin functionality. The DRDY pin functionality remains unaffected. SPI Reset SPI communication can be reset in several ways. In order to reset the SPI interface (without resetting the registers or the digital filter), the CS pin can be pulled high. Taking the RESET pin low causes the SPI interface to be reset along with all the other digital functions. In this case, the registers and the conversion are reset. SPI Communication During Sleep Mode When the START pin is low or the device is in sleep mode, only the RDATA, RDATAC, SDATAC, WAKEUP, and NOP commands can be issued. The RDATA command can be used to repeatedly read the last conversion result during sleep mode. Other commands do not function because the internal clock is shut down to save power during sleep mode. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 37 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com REGISTER DESCRIPTIONS ADS1246 REGISTER MAP Table 22. ADS1246 Register Map ADDRESS REGISTER BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 00h BCS BCS1 BCS0 0 0 0 0 0 1 01h VBIAS 0 0 0 0 0 0 VBIAS1 VBIAS0 02h MUX1 CLKSTAT 0 0 0 0 MUXCAL2 MUXCAL1 MUXCAL0 03h SYS0 0 PGA2 PGA1 PGA0 DR3 DR2 DR1 DR0 04h OFC0 OFC7 OFC6 OFC5 OFC4 OFC3 OFC2 OFC1 OFC0 05h OFC1 OFC15 OFC14 OFC13 OFC12 OFC11 OFC10 OFC9 OFC8 06h OFC2 OFC23 OFC22 OFC21 OFC20 OFC19 OFC18 OFC17 OFC16 07h FSC0 FSC7 FSC6 FSC5 FSC4 FSC3 FSC2 FSC1 FSC0 08h FSC1 FSC15 FSC14 FSC13 FSC12 FSC11 FSC10 FSC9 FSC8 09h FSC2 FSC23 FSC22 FSC21 FSC20 FSC19 FSC18 FSC17 FSC16 ID0 DRDY MODE 0 0 0 0Ah ID ID3 ID2 ID1 BIT 0 ADS1246 DETAILED REGISTER DEFINITIONS BCS—Burnout Current Source Register. These bits control the settling of the sensor burnout detect current source. BCS - ADDRESS 00h RESET VALUE = 01h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 BCS1 BCS0 0 0 0 0 0 1 Bits 7:6 BCS1:0 These bits select the magnitude of the sensor burnout detect current source. 00 = Burnout current source off (default) 01 = Burnout current source on, 0.5mA 10 = Burnout current source on, 2mA 11 = Burnout current source on, 10mA Bits 5:0 These bits must always be set to '000001'. 38 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 ADS1246 DETAILED REGISTER DEFINITIONS (continued) VBIAS—Bias Voltage Register. This register enables a bias voltage on the analog inputs. VBIAS - ADDRESS 01h RESET VALUE = 00h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0 0 0 0 0 0 VBIAS1 VBIAS0 Bits 7:2 These bits must always be set to '000000'. Bits 1:0 VBIAS1:0 These bits apply a bias voltage of midsupply (AVDD + AVSS)/2 to the selected analog input. Bit 0 is for AIN0, and bit 1 is for AIN1. 0 = Bias voltage not enabled (default) 1 = Bias voltage is applied to the analog input MUX—Multiplexer Control Register. MUX - ADDRESS 02h RESET VALUE = x0h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 CLKSTAT 0 0 0 0 MUXCAL2 MUXCAL1 MUXCAL0 Bit 7 CLKSTAT This bit is read-only and indicates whether the internal or external oscillator is being used. 0 = Internal oscillator in use 1 = External oscillator in use Bits 6:3 These bits must always be set to '0000'. Bits 2:0 MUXCAL2:0 These bits are used to select a system monitor. The MUXCAL selection supercedes selections from the VBIAS register. 000 = Normal operation (default) 001 = Offset calibration. The analog inputs are disconnected and AINP and AINN are internally connected to midsupply (AVDD + AVSS)/2. 010 = Gain calibration. The analog inputs are connected to the voltage reference. 011 = Temperature measurement. The inputs are connected to a diode circuit that produces a voltage proportional to the ambient temperature of the device.. Table 23 lists the ADC input connection and PGA settings for each MUXCAL setting. The PGA setting reverts to the original SYS0 register setting when MUXCAL is taken back to normal operation or offset measurement. Table 23. MUXCAL Settings MUXCAL[2:0] PGA GAIN SETTING ADC INPUT 000 Set by SYS0 register Normal operation 001 Set by SYS0 register Offset calibration: inputs shorted to midsupply (AVDD + AVSS)/2 010 Forced to 1 Gain calibration: VREFP – VREFN (full-scale) 011 Forced to 1 Temperature measurement diode Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 39 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com ADS1246 DETAILED REGISTER DEFINITIONS (continued) SYS0—System Control Register 0. SYS0 - ADDRESS 03h RESET VALUE = 00h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0 PGA2 PGA1 PGA0 DOR3 DOR2 DOR1 DOR0 Bit 7 These bits must always be set to '0'. Bits 6:4 PGA2:0 These bits determine the gain of the PGA. 000 = 1 (default) 001 = 2 010 = 4 011 = 8 100 = 16 101 = 32 110 = 64 111 = 128 Bits 3:0 DOR3:0 These bits select the output data rate of the ADC. Bits with a value higher than 1001 select the highest data rate of 2kSPS. 0000 = 5SPS (default) 0001 = 10SPS 0010 = 20SPS 0011 = 40SPS 0100 = 80SPS 0101 = 160SPS 0110 = 320SPS 0111 = 640SPS 1000 = 1000SPS 1001 to 1111 = 2000SPS OFC23:0 These bits make up the offset calibration coefficient register of the ADS1248. OFC0—Offset Calibration Coefficient Register 0 OFC0 - ADDRESS 04h RESET VALUE = 00h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 OFC7 OFC6 OFC5 OFC4 OFC3 OFC2 OFC1 OFC0 OFC1—Offset Calibration Coefficient Register 1 OFC1 - ADDRESS 05h RESET VALUE = 00h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 OFC15 OFC14 OFC13 OFC12 OFC11 OFC10 OFC9 OFC8 OFC2—Offset Calibration Coefficient Register 2 OFC2 - ADDRESS 06h 40 RESET VALUE = 00h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 OFC23 OFC22 OFC21 OFC20 OFC19 OFC18 OFC17 OFC16 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 ADS1246 DETAILED REGISTER DEFINITIONS (continued) FSC23:0 These bits make up the full-scale calibration coefficient register. FSC0—Full-Scale Calibration Coefficient Register 0 RESET VALUE IS PGA DEPENDENT (1) FSC0 - ADDRESS 07h (1) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FSC7 FSC6 FSC5 FSC4 FSC3 FSC2 FSC1 FSC0 The reset value for FSC is factory-trimmed for each PGA setting. Note: the factory-trimmed FSC reset value is automatically loaded whenever the PGA setting is changed. FSC1—Full-Scale Calibration Coefficient Register 1 RESET VALUE IS PGA DEPENDENT (1) FSC1 - ADDRESS 08h (1) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FSC15 FSC14 FSC13 FSC12 FSC11 FSC10 FSC9 FSC8 The reset value for FSC is factory-trimmed for each PGA setting. Note: the factory-trimmed FSC reset value is automatically loaded whenever the PGA setting is changed. FSC2—Full-Scale Calibration Coefficient Register 2 RESET VALUE IS PGA DEPENDENT (1) FSC2 - ADDRESS 09h (1) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FSC23 FSC22 FSC21 FSC20 FSC19 FSC18 FSC17 FSC16 The reset value for FSC is factory-trimmed for each PGA setting. Note: the factory-trimmed FSC reset value is automatically loaded whenever the PGA setting is changed. ID—ID Register IDAC0 - ADDRESS 0Ah RESET VALUE = x0h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 ID3 ID2 ID1 ID0 DRDY MODE 0 0 0 Bits 7:4 ID3:0 Read-only, factory-programmed bits; used for revision identification. Bit 3 DRDY MODE This bit sets the DOUT/DRDY pin functionality. In either setting of the DRDY MODE bit, the DRDY pin continues to indicate data ready, active low. 0 = DOUT/DRDY pin functions only as Data Out (default) 1 = DOUT/DRDY pin functions both as Data Out and Data Ready, active low Bits 2:0 These bits must always be set to '000'. Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 41 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com ADS1247 AND ADS1248 REGISTER MAP Table 24. ADS1247 and ADS1248 Register Map ADDRESS REGISTER BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 00h MUX0 BCS1 BCS0 MUX_SP2 MUX_SP1 MUX_SP0 MUX_SN2 MUX_SN1 MUX_SN0 01h VBIAS VBIAS7 VBIAS6 VBIAS5 02h MUX1 CLKSTAT 42 VREFCON1 VREFCON0 VBIAS4 VBIAS3 VBIAS2 VBIAS1 VBIAS0 REFSELT1 REFSELT0 MUXCAL2 MUXCAL1 MUXCAL0 03h SYS0 0 PGA2 PGA1 PGA0 DR3 DR2 DR1 DR0 04h OFC0 OFC7 OFC6 OFC5 OFC4 OFC3 OFC2 OFC1 OFC0 05h OFC1 OFC15 OFC14 OFC13 OFC12 OFC11 OFC10 OFC9 OFC8 06h OFC2 OFC23 OFC22 OFC21 OFC20 OFC19 OFC18 OFC17 OFC16 07h FSC0 FSC7 FSC6 FSC5 FSC4 FSC3 FSC2 FSC1 FSC0 08h FSC1 FSC15 FSC14 FSC13 FSC12 FSC11 FSC10 FSC9 FSC8 09h FSC2 FSC23 FSC22 FSC21 FSC20 FSC19 FSC18 FSC17 FSC16 0Ah IDAC0 ID3 ID2 ID1 ID0 DRDY MODE IMAG2 IMAG1 IMAG0 0Bh IDAC1 I1DIR3 I1DIR2 I1DIR1 I1DIR0 I2DIR3 I2DIR2 I2DIR1 I2DIR0 0Ch GPIOCFG IOCFG7 IOCFG6 IOCFG5 IOCFG4 IOCFG3 IOCFG2 IOCFG1 IOCFG0 0Dh GPIODIR IODIR7 IODIR6 IODIR5 IODIR4 IODIR3 IODIR2 IODIR1 IODIR0 0Eh GPIODAT IODAT7 IODAT6 IODAT5 IODAT4 IODAT3 IODAT2 IODAT1 IODAT0 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 ADS1247 and ADS1248 DETAILED REGISTER DEFINITIONS MUX0—Multiplexer Control Register 0. This register allows any combination of differential inputs to be selected on any of the input channels. Note that this setting can be superceded by the MUXCAL and VBIAS bits. MUX0 - ADDRESS 00h RESET VALUE = 01h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 BCS1 BCS0 MUX_SP2 MUX_SP1 MUX_SP0 MUX_SN2 MUX_SN1 MUX_SN0 Bits 7:6 BCS1:0 These bits select the magnitude of the sensor detect current source. 00 = Burnout current source off (default) 01 = Burnout current source on, 0.5mA 10 = Burnout current source on, 2mA 11 = Burnout current source on, 10mA Bits 5:3 MUX_SP2:0 Positive input channel selection bits. 000 = AIN0 (default) 001 = AIN1 010 = AIN2 011 = AIN3 100 = AIN4 (ADS1248 only) 101 = AIN5 (ADS1248 only) 110 = AIN6 (ADS1248 only) 111 = AIN7 (ADS1248 only) Bits 2:0 MUX_SN2:0 Negative input channel selection bits. 000 = AIN0 001 = AIN1 (default) 010 = AIN2 011 = AIN3 100 = AIN4 (ADS1248 only) 101 = AIN5 (ADS1248 only) 110 = AIN6 (ADS1248 only) 111 = AIN7 (ADS1248 only) VBIAS—Bias Voltage Register VBIAS - ADDRESS 01h RESET VALUE = 00h DEVICE BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 ADS1248 VBIAS7 VBIAS6 VBIAS5 VBIAS4 VBIAS3 VBIAS2 VBIAS1 VBIAS0 ADS1247 0 0 0 0 VBIAS3 VBIAS2 VBIAS1 VBIAS0 Bits 7:0 VBIAS7:0 These bits apply a bias voltage of midsupply (AVDD + AVSS)/2 to the selected analog input. 0 = Bias voltage not enabled (default) 1 = Bias voltage is applied on the corresponding analog input (bit 0 corresponds to AIN0, etc.). Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 43 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com ADS1247 and ADS1248 DETAILED REGISTER DEFINITIONS (continued) MUX1—Multiplexer Control Register 1 MUX1 - ADDRESS 02h RESET VALUE = 00h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 CLKSTAT VREFCON1 VREFCON0 REFSELT1 REFSELT0 MUXCAL2 MUXCAL1 MUXCAL0 Bit 7 CLKSTAT This bit is read-only and indicates whether the internal or external oscillator is being used. 0 = Internal oscillator in use 1 = External oscillator in use Bits 6:5 VREFCON1:0 These bits control the internal voltage reference. These bits allow the reference to be turned on or off completely, or allow the reference state to follow the state of the device. Note that the internal reference is required for operation of the IDAC functions. 00 = Internal reference is always off (default) 01 = Internal reference is always on 10 or 11 = Internal reference is on when a conversion is in progress and shuts down when the device receives a shutdown opcode or the START pin is taken low Bits 4:3 REFSELT1:0 These bits select the reference input for the ADC. 00 = REF0 input pair selected (default) 01 = REF1 input pair selected (ADS1248 only) 10 = Onboard reference selected 11 = Onboard reference selected and internally connected to REF0 input pair Bits 2:0 MUXCAL2:0 These bits are used to select a system monitor. The MUXCAL selection supercedes selections from registers MUX0 and MUX1 (MUX_SP, MUX_SN, and VBIAS). 000 = Normal operation (default) 001 = Offset measurement 010 = Gain measurement 011 = Temperature diode 100 = External REF1 measurement (ADS1248 only) 101 = External REF0 measurement 110 = AVDD measurement 111 = DVDD measurement Table 25 provides the ADC input connection and PGA settings for each MUXCAL setting. The PGA setting reverts to the original SYS0 register setting when MUXCAL is taken back to normal operation or offset measurement. Table 25. MUXCAL Settings 44 MUXCAL[2:0] PGA GAIN SETTING ADC INPUT 000 Set by SYS0 register Normal operation 001 Set by SYS0 register Inputs shorted to midsupply (AVDD + AVSS)/2 010 Forced to 1 VREFP – VREFN (full-scale) 011 Forced to 1 Temperature measurement diode 100 Forced to 1 (VREFP1 – VREFN1)/4 101 Forced to 1 (VREFP0 – VREFN0)/4 110 Forced to 1 (AVDD – AVSS)/4 111 Forced to 1 (DVDD – DVSS)/4 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 ADS1247 and ADS1248 DETAILED REGISTER DEFINITIONS (continued) SYS0—System Control Register 0 SYS0 - ADDRESS 03h RESET VALUE = 00h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0 PGA2 PGA1 PGA0 DOR3 DOR2 DOR1 DOR0 Bit 7 This bit must always be set to '0' Bits 6:4 PGA2:0 These bits determine the gain of the PGA. 000 = 1 (default) 001 = 2 010 = 4 011 = 8 100 = 16 101 = 32 110 = 64 111 = 128 Bits 3:0 DOR3:0 These bits select the output data rate of the ADC. Bits with a value higher than 1001 select the highest data rate of 2000SPS. 0000 = 5SPS (default) 0001 = 10SPS 0010 = 20SPS 0011 = 40SPS 0100 = 80SPS 0101 = 160SPS 0110 = 320SPS 0111 = 640SPS 1000 = 1000SPS 1001 to 1111 = 2000SPS OFC23:0 These bits make up the offset calibration coefficient register of the ADS1248. OFC0—Offset Calibration Coefficient Register 0 OFC0 - ADDRESS 04h RESET VALUE = 000000h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 OFC7 OFC6 OFC5 OFC4 OFC3 OFC2 OFC1 OFC0 OFC1—Offset Calibration Coefficient Register 1 OFC1 - ADDRESS 05h RESET VALUE = 000000h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 OFC15 OFC14 OFC13 OFC12 OFC11 OFC10 OFC9 OFC8 OFC2—Offset Calibration Coefficient Register 2 OFC2 - ADDRESS 06h RESET VALUE = 000000h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 OFC23 OFC22 OFC21 OFC20 OFC19 OFC18 OFC17 OFC16 Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 45 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com ADS1247 and ADS1248 DETAILED REGISTER DEFINITIONS (continued) FSC23:0 These bits make up the full-scale calibration coefficient register. FSC0—Full-Scale Calibration Coefficient Register 0 RESET VALUE IS PGA DEPENDENT (1) FSC0 - ADDRESS 07h (1) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FSC7 FSC6 FSC5 FSC4 FSC3 FSC2 FSC1 FSC0 The reset value for FSC is factory-trimmed for each PGA setting. Note: the factory-trimmed FSC reset value is automatically loaded whenever the PGA setting is changed. FSC1—Full-Scale Calibration Coefficient Register 1 RESET VALUE IS PGA DEPENDENT (1) FSC1 - ADDRESS 08h (1) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FSC15 FSC14 FSC13 FSC12 FSC11 FSC10 FSC9 FSC8 The reset value for FSC is factory-trimmed for each PGA setting. Note: the factory-trimmed FSC reset value is automatically loaded whenever the PGA setting is changed. FSC2—Full-Scale Calibration Coefficient Register 2 RESET VALUE IS PGA DEPENDENT (1) FSC2 - ADDRESS 09h (1) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FSC23 FSC22 FSC21 FSC20 FSC19 FSC18 FSC17 FSC16 The reset value for FSC is factory-trimmed for each PGA setting. Note: the factory-trimmed FSC reset value is automatically loaded whenever the PGA setting is changed. IDAC0—IDAC Control Register 0 IDAC0 - ADDRESS 0Ah RESET VALUE = x0h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 ID3 ID2 ID1 ID0 DRDY MODE IMAG2 IMAG1 IMAG0 Bits 7:4 ID3:0 Read-only, factory-programmed bits; used for revision identification. Bit 3 DRDY MODE This bit sets the DOUT/DRDY pin functionality. In either setting of the DRDY MODE bit, the DRDY pin continues to indicate data ready, active low. 0 = DOUT/DRDY pin functions only as Data Out (default) 1 = DOUT/DRDY pin functions both as Data Out and Data Ready, active low Bits 2:0 IMAG2:0 The ADS1247/8 have two programmable current source DACs that can be used for sensor excitation. The IMAG bits control the magnitude of the excitation current. The IDACs require the internal reference to be on. 000 = off (default) 001 = 50mA 010 = 100mA 011 = 250mA 100 = 500mA 101 = 750mA 110 = 1000mA 111 = 1500mA 46 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 ADS1247 and ADS1248 DETAILED REGISTER DEFINITIONS (continued) IDAC1—IDAC Control Register 1 IDAC1 - ADDRESS 0Bh RESET VALUE = FFh DEVICE BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 ADS1248 I1DIR3 I1DIR2 I1DIR1 I1DIR0 I2DIR3 I2DIR2 I2DIR1 I2DIR0 ADS1247 0 0 I1DIR1 I1DIR0 0 0 I2DIR1 I2DIR0 The two IDACs on the ADS1247/8 can be routed to either the IEXC1 and IEXC2 output pins or directly to the analog inputs. Bits 7:4 I1DIR3:0 These bits select the output pin for the first current source DAC. 0000 = AIN0 0001 = AIN1 0010 = AIN2 0011 = AIN3 0100 = AIN4 (ADS1248 only) 0101 = AIN5 (ADS1248 only) 0110 = AIN6 (ADS1248 only) 0111 = AIN7 (ADS1248 only) 10x0 = IEXT1 (ADS1248 only) 10x1 = IEXT2 (ADS1248 only) 11xx = Disconnected (default) Bits 3:0 I2DIR3:0 These bits select the output pin for the second current source DAC. 0000 = AIN0 0001 = AIN1 0010 = AIN2 0011 = AIN3 0100 = AIN4 (ADS1248 only) 0101 = AIN5 (ADS1248 only) 0110 = AIN6 (ADS1248 only) 0111 = AIN7 (ADS1248 only) 10x0 = IEXT1 (ADS1248 only) 10x1 = IEXT2 (ADS1248 only) 11xx = Disconnected (default) Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 47 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com ADS1247 and ADS1248 DETAILED REGISTER DEFINITIONS (continued) GPIOCFG—GPIO Configuration Register. The GPIO and analog pins are shared as follows: GPIO0 shared with REFP0 GPIO1 shared with REFN0 GPIO2 shared with AIN2 GPIO3 shared with AIN3 GPIO4 shared with AIN4 (ADS1248) GPIO5 shared with AIN5 (ADS1248) GPIO6 shared with AIN6 (ADS1248) GPIO7 shared with AIN7 (ADS1248) GPIOCFG - ADDRESS 0Ch RESET VALUE = 00h DEVICE BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 ADS1248 IOCFG7 IOCFG6 IOCFG5 IOCFG4 IOCFG3 IOCFG2 IOCFG1 IOCFG0 ADS1247 0 0 0 0 IOCFG3 IOCFG2 IOCFG1 IOCFG0 Bits 7:0 IOCFG7:0 These bits enable the GPIO because the GPIO pins are shared with the analog pins. Note that the ADS1248 uses all the IOCFG bits, whereas the ADS1247 uses only bits 3:0. 0 = The pin is used as an analog input (default) 1 = The pin is used as a GPIO pin GPIODIR—GPIO Direction Register GPIODIR - ADDRESS 0Dh RESET VALUE = 00h DEVICE BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 ADS1248 IODIR7 IODIR6 IODIR5 IODIR4 IODIR3 IODIR2 IODIR1 IODIR0 ADS1247 0 0 0 0 IODIR3 IODIR2 IODIR1 IODIR0 Bits 7:0 IODIR7:0 These bits control the direction of the GPIO when enabled by the IOCFG bits. Note that the ADS1248 uses all the IODIR bits, whereas the ADS1247 uses only bits 3:0. 0 = The GPIO is an output (default) 1 = The GPIO is an input GPIODAT—GPIO Data Register GPIODAT - ADDRESS 0Eh BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 ADS1248 IODAT7 IODAT6 IODAT5 IODAT4 IODAT3 IODAT2 IODAT1 IODAT0 ADS1247 0 0 0 0 IODAT3 IODAT2 IODAT1 IODAT0 Bits 7:0 48 RESET VALUE = 00h DEVICE IODAT7:0 If a GPIO pin is enabled in the GPIOCFG register and configured as an output in the GPIO Direction register (GPIODIR), the value written to this register appears on the appropriate GPIO pin. If a GPIO pin is configured as an input in GPIODIR, reading this register returns the value of the digital I/O pins. Note that the ADS1248 uses all eight IODAT bits, while the ADS1247 uses only bits 3:0. Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 SPI COMMANDS SPI COMMAND DEFINITIONS The commands shown in Table 26 control the operation of the ADS1246/7/8. Some of the commands are stand-alone commands (for example, RESET), whereas others require additional bytes (for example, WREG requires command, count, and the data bytes). Operands: n = number of registers to be read or written (number of bytes – 1) r = register (0 to 15) x = don't care Table 26. SPI Commands COMMAND TYPE System Control Data Read Read Register Write Register Calibration COMMAND DESCRIPTION 1st COMMAND BYTE WAKEUP Exit sleep mode 0000 000x (00h, 01h) SLEEP Enter sleep mode 0000 001x (02h, 03h) SYNC Synchronize the A/D conversion 0000 010x (04h, 05h) RESET Reset to power-up values 0000 011x (06h, 07h) NOP No operation 1111 1111 (FFh) 2nd COMMAND BYTE 0000-010x (04,05h) RDATA Read data once 0001 001x (12h, 13h) RDATAC Read data continuously 0001 010x (14h, 15h) SDATAC Stop reading data continuously 0001 011x (16h, 17h) RREG Read from register rrrr 0010 rrrr (2xh) 0000_nnnn 0000_nnnn WREG Write to register rrrr 0100 rrrr (4xh) SYSOCAL System offset calibration 0110 0000 (60h) SYSGCAL System gain calibration 0110 0001 (61h) SELFOCAL Self offset calibration 0110 0010 (62h) Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 49 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com SYSTEM CONTROL COMMANDS WAKEUP—Wake up from sleep mode that is set by the SLEEP command. Use this command to awaken the device from sleep mode. After execution of the WAKEUP command, the device wakes up on the rising edge of the eighth SCLK. SLEEP—Set the device to sleep mode; can only be awakened by the WAKEUP command. This command places the part into a sleep (power-saving) mode. When the SLEEP command is issued, the device completes the current conversion and then goes into sleep mode. Note that this command does not automatically power-down the internal voltage reference; see the VREFCON bits in the MUX1 register for each device for further details. To exit sleep mode, issue the WAKEUP command. Single conversions can be performed by issuing a WAKEUP command followed by a SLEEP command. Both WAKEUP and SLEEP are the software command equivalents of using the START pin to control the device. DIN SLEEP WAKEUP 0000 001X 0000 000X SCLK Eighth SCLK DRDY Status Normal Mode Sleep Mode Normal Mode Finish Current Conversion Start New Conversion Figure 70. SLEEP and WAKEUP Commands Operation SYNC—Synchronize DRDY. This command resets the ADC digital filter and starts a new conversion. The DRDY pin from multiple devices connected to the same SPI bus can be synchronized by issuing a SYNC command to all of devices simultaneously. SYNC DIN 0000 010X 0000 010X SCLK 2 tOSC Synchronization Occurs Here Figure 71. SYNC Command Operation RESET—Reset the device to power-up state. This command restores the registers to the respective power-up values. This command also resets the digital filter. RESET is the command equivalent of using the RESET pin to reset the device. However, the RESET command does not reset the SPI interface. If the RESET command is issued when the SPI interface is in the wrong state, the device does not reset. The CS pin can be used to reset SPI interface first, and then a RESET command can be issued to reset the device. The RESET command holds the registers and the decimation filter in a reset state for 0.6ms when the system clock frequency is 4.096MHz, similar to the hardware reset. Therefore, SPI communication can be only be started 0.6ms after the RESET command is issued, as shown in Figure 72. Any SPI Command DIN RESET 1 8 SCLK 0.6ms Figure 72. SPI Communication After an SPI Reset 50 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 DATA RETRIEVAL COMMANDS RDATAC—Read data continuously. The RDATAC command enables the automatic loading of a new conversion result into the output data register. In this mode, the conversion result can be received once from the device after the DRDY signal goes low by sending 24 SCLKs. It is not necessary to read back all the bits, as long as the number of bits read out is a multiple of eight. The RDATAC command must be issued after DRDY goes low, and the command takes effect on the next DRDY. Be sure to complete data retrieval (conversion result or register read-back) before DRDY goes low, or the resulting data will be corrupt. Successful register read operations in RDATAC mode require the knowledge of when the next DRDY falling edge occurs. DRDY RDATAC DIN NOP 0001 010X 24 Bits DOUT SCLK 1 8 1 24 Figure 73. Read Data Continuously SDATAC—Stop reading data continuously. The SDATAC command terminates the RDATAC mode. Afterwards, the conversion result is not automatically loaded into the output shift register when DRDY goes low, and register read operations can be performed without interruption from new conversion results being loaded into the output shift register. Use the RDATA command to retrieve conversion data. The SDATAC command takes effect after the next DRDY. DRDY SDATAC DIN 0001 011X Figure 74. Stop Reading Data Continuously Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 51 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com RDATA—Read data once. The RDATA command loads the most recent conversion result into the output register. After issuing this command, the conversion result can be read out by sending 24 SCLKs, as shown in Figure 75. This command also works in RDATAC mode. When performing multiple reads of the conversion result, the RDATA command can be sent when the last eight bits of the conversion result are being shifted out during the course of the first read operation by taking advantage of the duplex communication nature of the SPI interface, as shown in Figure 76. DRDY RDATA 0001 001X DIN DOUT NOP NOP NOP MSB Mid-Byte LSB SCLK 1 8 1 24 Figure 75. Read Data Once 1 2 7 8 9 10 23 24 1 2 23 24 SCLK DOUT D[23] D[22] NOP DIN D[17] D[16] D[15] D[14] NOP NOP D[1] D[0] RDATA D[23] D[22] NOP D[1] D[0] NOP DRDY Figure 76. Using RDATA in Full-Duplex Mode 52 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 USER REGISTER READ AND WRITE COMMANDS RREG—Read from registers. This command outputs the data from up to 16 registers, starting with the register address specified as part of the instruction. The number of registers read is one plus the second byte. If the count exceeds the remaining registers, the addresses wrap back to the beginning. First Command Byte: 0010 rrrr, where rrrr is the address of the first register to read. Second Command Byte: 0000 nnnn, where nnnn is the number of bytes to read –1. It is not possible to use the full-duplex nature of the SPI interface when reading out the register data. For example, a SYNC command cannot be issued when reading out the VBIAS and MUX1 data, as shown in Figure 77. Any command sent during the readout of the register data is ignored. Thus, it is advisable to send NOP through the DIN when reading out the register data. 1st 2nd Command Command Byte Byte DIN 0010 0001 0000 0001 DOUT VBIAS MUX1 Data Byte Data Byte Figure 77. Read from Register WREG—Write to registers. This command writes to the registers, starting with the register specified as part of the instruction. The number of registers that are written is one plus the value of the second byte. First Command Byte: 0100 rrrr, where rrrr is the address of the first register to be written. Second Command Byte: 0000 nnnn, where nnnn is the number of bytes to be written – 1. Data Byte(s): data to be written to the registers. DIN 0100 0010 0000 0001 MUX2 SYS0 1st 2nd Command Command Data Byte Data Byte Figure 78. Write to Register Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 53 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com CALIBRATION COMMANDS The ADS1246/7/8 provide system and offset calibration commands and a system gain calibration command. SYSOCAL—Offset system calibration. This command initiates a system offset calibration. For a system offset calibration, the input should be externally set to zero. The OFC register is updated when this operation completes. SYSGCAL—System gain calibration. This command initiates the system gain calibration. For a system gain calibration, the input should be set to full-scale. The FSC register is updated after this operation. SELFOCAL—Self offset calibration. This command initiates a self-calibration for offset. The device internally shorts the inputs and performs the calibration. The OFC register is updated after this operation. Calibration Starts Calibration Complete tCAL DRDY Calibration Command DIN SCLK 1 8 Figure 79. Calibration Command 54 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 APPLICATION INFORMATION SPI COMMUNICATION EXAMPLES negative terminal of both sensors (that is, channels AIN1 and AIN3). All these settings can be changed by performing a block write operation on the first four registers of the device. After the DRDY pin goes low, the conversion result can be immediately retrieved by sending in 16 SPI clock pulses because the device defaults to RDATAC mode. As the conversion result is being retrieved, the active input channels can be switched to AIN2 and AIN3 by writing into the MUX0 register in a full-duplex manner, as shown in Figure 80. The write operation is completed with an additional eight SPI clock pulses. The time from the write operation into the MUX0 register to the next DRDY low transition is shown in Figure 80 and is 0.513ms in this case. After DRDY goes low, the conversion result can be retrieved and the active channel can be switched as before. This section contains several examples of SPI communication with the ADS1246/7/8, including the power-up sequence. Channel Multiplexing Example This first example applies only to the ADS1247 and ADS1248. It explains a method to use the device with two sensors connected to two different analog channels. Figure 80 shows the sequence of SPI operations performed on the device. After power-up, 216 system clocks are required before communication may be started. During the first 216 system clock cycles, the devices are internally held in a reset state. In this example, one of the sensors is connected to channels AIN0 and AIN1 and the other sensor is connected to channels AIN2 and AIN3. The ADC is operated at a data rate of 2kSPS. The PGA gain is set to 32 for both sensors. VBIAS is connected to the Power-up sequence 16ms ADC initial setup Multiplexer change is channel 2 Data Retrieval for Channel 2 Conversion (1) DVDD START RESET CS WREG DIN WREG 3 00 01 02 03 NOP 00 00 SCLK Conversion result for channel 2 Conversion result for channel 1 DOUT DRDY tDRDY Initial setting: AIN0 is the positive channel, AIN1 is the negative channel, internal reference selected, PGA gain = 32, data rate = 2kSPS, VBIAS is connected to the negative pins AIN1 and AIN3. 0.513ms for MUX0 Write AIN2 is the positive channel, AIN3 is the negative channel. (1) For fOSC = 4.096MHz. Figure 80. SPI Communication Sequence for Channel Multiplexing Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 55 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com Sleep Mode Example This second example deals with performing one conversion after power-up and then entering into the power-saving sleep mode. In this example, a sensor is connected to input channels AIN0 and AIN1. Commands to set up the devices must occur at least 216 system clock cycles after powering up the devices. The ADC operates at a data rate of 2kSPS. The PGA gain is set to 32 for both sensors. VBIAS is connected to the negative terminal of both the sensors (that is, channel AIN1). All these settings can Power-up sequence 16ms be changed by performing a block write operation on the first four registers of the device. After performing the block write operation, the START pin can be taken low. The device enters the power-saving sleep mode as soon as DRDY goes low 0.575ms after writing into the SYS0 register. The conversion result can be retrieved even after the device enters sleep mode by sending 16 SPI clock pulses. ADC initial setup (1) ADC is put to sleep after a single conversion. Data are retrieved when ADC is sleeping. DVDD START RESET CS WREG DIN NOP 00 01 02 03 SCLK Conversion result for channel 1 DOUT DRDY Initial setting: AIN0 is the positive channel, AIN1 is the negative channel, internal reference selected, PGA gain = 32, data rate = 2kSPS, VBIAS is connected to the negative pins, AIN1 and AIN3. tDRDY (0.575ms) ADC enters power-saving sleep mode (1) For fOSC = 4.096MHz. Figure 81. SPI Communication Sequence for Entering Sleep Mode After a Conversion 56 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 Hardware-Compensated, Three-Wire RTD Measurement Example be equal to the resistance of the PT-100 sensor at +25°C (approximately 110Ω). The IDAC current is set to 1.5mA. This setting results in a differential input swing of ±14.7mV at the inputs of the ADC. The PGA gain is set to 128. The full-scale input for the ADC is ±19.53mV. Fixing RBIAS at 833Ω fixes the reference at 2.5V and the input common-mode at approximately 2.7V, ensuring that the voltage at AIN0 is far away from the IDAC compliance voltage. Figure 82 is an application circuit to measure temperatures in the range of 0°C to +50°C using a PT-100 RTD and the ADS1247 or ADS1248 in a three-wire, hardware-compensated topology. The two onboard matched current DACs of the ADS1247/8 are ideally suited for implementing the three-wire RTD topology. This circuit uses a ratiometric approach, where the reference is derived from the IDAC currents in order to achieve excellent noise performance. The resistance of the PT-100 changes from 100Ω at 0°C to 119.6Ω at +50°C. The compensating resistor (RCOMP) has been chosen to The maximum number of noise-free output codes for this circuit in the 0°C to +50°C temperature range is (2ENOB)(14.7mV)/19.53mV. +5V +3.3V IN TPS79333 0.1mF EN VOUT NR GND AVDD DVDD IDAC1 1.5mA RTD RL(1) 15W AIN0 RL(1) 15W RCOMP(2) 110W AIN1 2.2mF RESET IDAC2 1.5mA PGA MSP430 or other Microprocessor Modulator Gain = 128 RL(1) 15W VDD SCLK REFP0 DIN (2) RBIAS 833W ADS1247/48 DOUT/DRDY CS REFN0 START AVSS (1) RTD line resistances. (2) RBIAS and RCOMP should be as close to the ADC as possible. DGND CLK GND Figure 82. Three-Wire RTD Application with Hardware Compensation Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 57 ADS1246 ADS1247 ADS1248 SBAS426D – AUGUST 2008 – REVISED MARCH 2010 www.ti.com REVISION HISTORY NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision C (August 2009) to Revision D Page • Updated Description section ................................................................................................................................................. 1 • Added Analog Inputs, Full-scale input voltage maximum specification in Electrical Characteristics .................................... 4 • Changed Analog Inputs, Absolute input current parameter of Electrical Characteristics ..................................................... 4 • Added new footnote 1 to Electrical Characteristics .............................................................................................................. 4 • Changed conditions of System Performance, Power-supply rejection parameter of Electricsl Characteristics ................... 4 • Changed typical specification of Current Sources (IDACS), Initial mismatch parameter of Electrical Characteristics ........ 5 • Changed typical specification of Current Sources (IDACS), Temperature drift parameter of Electrical Characteristics ...... 5 • Changed Power Supply, AVDD current typical specification for 3.3V parameter in Electrical Characteristics .................... 5 • Changed title of Table 6 ...................................................................................................................................................... 13 • Changed title of Table 7 ...................................................................................................................................................... 14 • Changed title of Table 9 ...................................................................................................................................................... 15 • Updated Figure 5 ................................................................................................................................................................ 16 • Updated Figure 6 ................................................................................................................................................................ 16 • Added Figure 7, Noise Histogram Plot ............................................................................................................................... 16 • Added Figure 8, Noise Histogram Plot ............................................................................................................................... 16 • Updated Figure 9 ................................................................................................................................................................ 16 • Added Figure 10, RMS Noise vs Input Signal .................................................................................................................... 16 • Updated Figure 11 .............................................................................................................................................................. 17 • Updated Figure 12 .............................................................................................................................................................. 17 • Updated Figure 13 .............................................................................................................................................................. 17 • Updated Figure 14 .............................................................................................................................................................. 17 • Added Figure 15, Offset Drift vs Temperature .................................................................................................................... 17 • Added Figure 16, Offset Drift vs Temperature .................................................................................................................... 17 • Added Figure 17, Offset vs Temperature ........................................................................................................................... 18 • Added Figure 18, Offset vs Temperature ........................................................................................................................... 18 • Updated Figure 19 .............................................................................................................................................................. 18 • Updated Figure 20 .............................................................................................................................................................. 18 • Updated Figure 21 .............................................................................................................................................................. 18 • Updated Figure 22 .............................................................................................................................................................. 18 • Added Figure 23, Gain vs Temperature ............................................................................................................................. 19 • Added Figure 24, Gain vs Temperature ............................................................................................................................. 19 • Added Figure 25, Gain vs Temperature ............................................................................................................................. 19 • Added Figure 26, Gain vs Temperature ............................................................................................................................. 19 • Updated Figure 29 .............................................................................................................................................................. 20 • Added Figure 31, Analog Current vs Temperature ............................................................................................................. 20 • Added Figure 32, Digital Current vs Temperature .............................................................................................................. 20 • Added Figure 42, Power-Supply Rejection vs Gain ........................................................................................................... 22 • Added Figure 43, Internal VREF Initial Accuracy Histogram ................................................................................................ 22 • Added Figure 44, IDAC Initial Accuracy Histogram ............................................................................................................ 22 • Added Figure 45, IDAC Mismatch Histogram ..................................................................................................................... 22 • Changed Table 11 .............................................................................................................................................................. 25 • Updated Figure 55 .............................................................................................................................................................. 27 58 Submit Documentation Feedback Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 ADS1246 ADS1247 ADS1248 www.ti.com SBAS426D – AUGUST 2008 – REVISED MARCH 2010 • Updated Figure 56 .............................................................................................................................................................. 27 • Revised VREFCOM description in Internal Voltage Reference section ............................................................................. 29 • Changed fourth row entry of final output code column in Table 16 .................................................................................... 31 • Added ADC Power-Up section ........................................................................................................................................... 32 • Added Channel Cycling and Overload Recovery section ................................................................................................... 34 • Changed first three rows of hardware reset columns in Table 20 ...................................................................................... 35 • Revised Channel Multiplexing Example section ................................................................................................................. 55 • Revised Sleep Mode Example section ............................................................................................................................... 56 Copyright © 2008–2010, Texas Instruments Incorporated Product Folder Link(s): ADS1246 ADS1247 ADS1248 Submit Documentation Feedback 59 PACKAGE OPTION ADDENDUM www.ti.com 24-May-2010 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) Samples (Requires Login) ADS1246IPW ACTIVE TSSOP PW 16 90 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Request Free Samples ADS1246IPWR ACTIVE TSSOP PW 16 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Purchase Samples ADS1247IPW ACTIVE TSSOP PW 20 70 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Request Free Samples ADS1247IPWR ACTIVE TSSOP PW 20 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Purchase Samples ADS1248IPW ACTIVE TSSOP PW 28 50 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Purchase Samples ADS1248IPWR ACTIVE TSSOP PW 28 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Purchase Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. Addendum-Page 1 PACKAGE OPTION ADDENDUM www.ti.com 24-May-2010 In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 17-Feb-2010 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 5.6 1.6 8.0 12.0 Q1 ADS1246IPWR TSSOP PW 16 2000 330.0 12.4 7.0 ADS1247IPWR TSSOP PW 20 2000 330.0 16.4 6.95 7.1 1.6 8.0 16.0 Q1 ADS1248IPWR TSSOP PW 28 2000 330.0 16.4 7.1 10.4 1.6 12.0 16.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 17-Feb-2010 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS1246IPWR TSSOP PW 16 2000 346.0 346.0 29.0 ADS1247IPWR TSSOP PW 20 2000 346.0 346.0 33.0 ADS1248IPWR TSSOP PW 28 2000 346.0 346.0 33.0 Pack Materials-Page 2 MECHANICAL DATA MTSS001C – JANUARY 1995 – REVISED FEBRUARY 1999 PW (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 14 PINS SHOWN 0,30 0,19 0,65 14 0,10 M 8 0,15 NOM 4,50 4,30 6,60 6,20 Gage Plane 0,25 1 7 0°– 8° A 0,75 0,50 Seating Plane 0,15 0,05 1,20 MAX PINS ** 0,10 8 14 16 20 24 28 A MAX 3,10 5,10 5,10 6,60 7,90 9,80 A MIN 2,90 4,90 4,90 6,40 7,70 9,60 DIM 4040064/F 01/97 NOTES: A. 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