Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsData collecting ICsData acquisition IC - AD converter (ADC) Internal VSSOP 10

SPI

Interface

Oscillator

Voltage

Reference

High Accuracy

Temp Sensor

MUX

PGA

16-Bit DS

ADC

GND

2 V

500 W

0.1 Fm

1 Fm

0.1 Fm

GND

1 MW

GND

2 V

500 W

1 Fm

0.1 Fm

GND

1 MW

GND

2 V

0.1 Fm

GND

AIN0

AIN1

AIN2

AIN3

SCLK

VDD

GND

DOUT/DRDY

DIN

Device

1 MW

GND

ADS1118

www.ti.com

SBAS457D –OCTOBER 2010–REVISED OCTOBER 2013

Ultra-Small, Low-Power, SPI™-Compatible, 16-Bit

Analog-to-Digital Converter and Temperature Sensor with Internal Reference

Check for Samples: ADS1118

FEATURES

DESCRIPTION

The ADS1118 is a precision analog-to-digital

• Ultra-Small QFN Package:

converter (ADC) with 16 bits of resolution offered in

2 mm × 1,5 mm × 0,4 mm

an ultra-small, leadless QFN-10 package or an

• Wide Supply Range: 2.0 V to 5.5 V

MSOP-10 package. The ADS1118 is designed with

• Low Current Consumption:

precision, power, and ease of implementation in

mind. The ADS1118 features an integrated voltage

– Continuous Mode: Only 150 μA

reference and oscillator. Data are transferred via a

– Single-Shot Mode: Auto Power-Down

serial peripheral interface (SPI). The ADS1118

• Programmable Data Rate:

operates from a single power supply ranging from

8 SPS to 860 SPS

2.0 V to 5.5 V.

• Single-Cycle Settling

The ADS1118 can perform conversions at rates up to

860 samples per second (SPS). A programmable

• Internal Low-Drift Voltage Reference

gain amplifier (PGA) is integrated in the ADS1118

• Internal Temperature Sensor:

that offers input ranges from as low as ±256 mV up to

0.5°C (max) Error

the supply rails, allowing both large and small signals

• Internal Oscillator

to be measured with high resolution. The ADS1118

also features an input multiplexer (MUX) that provides

• Internal PGA

two differential or four single-ended inputs. The

• Four Single-Ended or Two Differential Inputs

ADS1118 can also function as a high-accuracy

temperature sensor. This temperature sensor can be

APPLICATIONS

used for system-level temperature monitoring or cold

junction compensation for thermocouples.

• Temperature Measurement:

– Thermocouple Measurement

The ADS1118 operates either in continuous

conversion mode or single-shot mode that

– Cold Junction Compensation

automatically powers down after a conversion.

– Thermistor Measurement

Single-shot mode significantly reduces current

• Portable Instrumentation

consumption during idle periods. The ADS1118 is

specified from –40°C to +125°C.

• Factory Automation and Process Controls

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2SPI is a trademark of Motorola.

3All 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.

Summary of content (40 pages)

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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 Ultra-Small, Low-Power, SPI™-Compatible, 16-Bit Analog-to-Digital Converter and Temperature Sensor with Internal Reference Check for Samples: ADS1118 FEATURES DESCRIPTION • The ADS1118 is a precision analog-to-digital converter (ADC) with 16 bits of resolution offered in an ultra-small, leadless QFN-10 package or an MSOP-10 package. The ADS1118 is designed with precision, power, and ease of implementation in mind.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 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.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 ELECTRICAL CHARACTERISTICS Maximum and minimum specifications are at TA = –40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All specifications are at VDD = 3.3 V, data rate = 8 SPS, and full-scale (FS) = ±2.048 V, unless otherwise noted.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com ELECTRICAL CHARACTERISTICS (continued) Maximum and minimum specifications are at TA = –40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All specifications are at VDD = 3.3 V, data rate = 8 SPS, and full-scale (FS) = ±2.048 V, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT DIGITAL INPUT/OUTPUT Logic level VIH 0.7 VDD VDD V VIL GND 0.2 VDD V VOH IOH = 1 mA 0.
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ADS1118 www.ti.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com SPI TIMING CHARACTERISTICS tCSH CS tSCLK tCSSC tSPWH tSCCS SCLK tDIHD tDIST tSPWL tSCSC DIN tCSDOD tDOHD tDOPD Hi-Z tCSDOZ Hi-Z DOUT Figure 1. Serial Interface Timing TIMING REQUIREMENTS: SERIAL INTERFACE TIMING At TA = –40°C to +125°C and VDD = 2.0 V to 5.5 V, unless otherwise noted.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 TYPICAL CHARACTERISTICS At TA = +25°C and VDD = 3.3 V, unless otherwise noted. TOTAL ERROR vs INPUT SIGNAL 4 DATA RATE vs TEMPERATURE 4 3 2 2 Data Rate Error (%) Total Error (mV) Includes noise, offset, and gain error. 3 1 0 -1 -2 FS = ±2.048 V Data Rate = 860 SPS Differential Inputs -3 -4 -2.048 -1.024 0 VDD = 2.0 V VDD = 3.3 V VDD = 5.0 V 1 0 −1 −2 −3 1.024 −4 −60 −40 −20 2.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C and VDD = 3.3 V, unless otherwise noted. INL vs INPUT SIGNAL INL vs INPUT SIGNAL 5 10 FS = ±2.048V VDD = 3.3V DR = 8SPS Best Fit 3 2 1 0 −1 −2 −40°C +25°C +125°C −3 −4 −5 −2 −1.5 −40°C +25°C +125°C 8 Integral Nonlinearity (ppm) Integral Nonlinearity (ppm) 4 6 4 2 0 −2 −4 FS = ±0.512V VDD = 3.3V DR = 8SPS Best Fit −6 −8 −1 −0.5 0 0.5 Input Signal (V) 1 1.5 −10 −0.5 2 −0.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 TYPICAL CHARACTERISTICS (continued) At TA = +25°C and VDD = 3.3 V, unless otherwise noted. SINGLE-ENDED OFFSET VOLTAGE vs TEMPERATURE SINGLE-ENDED OFFSET VOLTAGE vs SUPPLY 60 60 AIN0 to GND AIN1 to GND AIN2 to GND AIN3 to GND AIN0 to GND AIN1 to GND AIN2 to GND AIN3 to GND 40 Offset Voltage (µV) Offset Voltage (µV) 40 20 0 −20 −40 20 0 −20 −40 FS = ±2.048V −60 −40 −20 FS = ±2.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C and VDD = 3.3 V, unless otherwise noted. GAIN ERROR vs TEMPERATURE GAIN ERROR vs SUPPLY 0.15 0.05 0.04 0.1 0.02 Gain Error (%) Gain Error (%) 0.03 0.01 0 FS = ±0.256V FS = ±0.512V FS = ±1.024V FS = ±2.048V FS = ±4.096V FS = ±6.144V −0.01 −0.02 −0.03 −0.04 −0.05 −40 −20 0 20 40 60 80 Temperature (°C) 100 120 0.05 FS = ±256 mV 0 FS = ±2.048 V -0.05 -0.1 -0.15 140 2 2.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 TYPICAL CHARACTERISTICS (continued) At TA = +25°C and VDD = 3.3 V, unless otherwise noted. TEMPERATURE SENSOR ERROR vs AMBIENT TEMPERATURE (MSOP) TEMPERATURE SENSOR ERROR HISTOGRAM (MSOP) 1 40 Average Temperature Error Average ± 3 sigma Average ± 6 sigma 0.6 TA = −40°C 48 units from 3 production lots. 35 Number of Occurrences 0.4 0.2 0 −0.2 −0.4 −0.6 30 25 20 15 10 5 −0.8 G023 0.5 0.4 0.3 0.2 0 120 0.1 100 0 80 −0.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C and VDD = 3.3 V, unless otherwise noted. TEMPERATURE SENSOR ERROR vs AMBIENT TEMPERATURE (QFN) 1 80 Average Temperature Error Average 3 sigma Average 6 sigma 0.8 0.6 TA í °C 94 units from production. 70 Number of Occurrences 0.4 0.2 0 -0.2 -0.4 -0.6 60 50 40 30 20 10 -0.8 -1 C007 0.5 0.4 0.3 0.2 120 0.1 100 0 80 -0.1 20 40 60 Temperature (C) -0.2 0 -0.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 OVERVIEW The ADS1118 is a very small, low-power, 16-bit, delta-sigma (ΔΣ) analog-to-digital converter (ADC). The ADS1118 is extremely easy to configure and design into a wide variety of applications, and allows precise measurements to be obtained with very little effort. Both experienced and novice users of data converters find designing with the ADS1118 family to be intuitive and problem-free.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com MULTIPLEXER The ADS1118 contains an input multiplexer, as shown in Figure 39. Either four single-ended or two differential signals can be measured. Additionally, AIN0, AIN1, and AIN2 may be measured differentially to AIN3. The multiplexer is configured by three bits (MUX[2:0], bits 14-12) in the Config register.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 ANALOG INPUTS The ADS1118 uses a switched-capacitor input stage where capacitors are continuously charged and then discharged to measure the voltage between AINP and AINN. The capacitors used are small, and to external circuitry, the average loading appears resistive. This structure is shown in Figure 40. The resistance is set by the capacitor values and the rate at which they are switched.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com The typical value of the input impedance cannot be neglected. Unless the input source has a low impedance, the ADS1118 input impedance may affect the measurement accuracy. For sources with high output impedance, buffering may be necessary. Note that active buffers introduce noise, and also introduce offset and gain errors. All of these factors should be considered in high-accuracy applications.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 DATA FORMAT The ADS1118 provides 16 bits of data in binary twos complement format. The positive full-scale input produces an output code of 7FFFh and the negative full-scale input produces an output code of 8000h. The output clips at these codes for signals that exceed full-scale. Table 3 summarizes the ideal output codes for different input signals. Figure 42 shows code transitions versus input voltage. Table 3.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com TEMPERATURE SENSOR The temperature measurement mode of the ADS1118 is configured as a 14-bit result when enabled. Two bytes must be read to obtain data. The first byte is the most significant byte (MSB), followed by a second byte, the least significant byte (LSB). The first 14 bits are used to indicate temperature.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 ALIASING As with any data converter, if the input signal contains frequencies greater than half the data rate, aliasing occurs. To prevent aliasing, the input signal must be bandlimited. However, some signals are inherently bandlimited. For example, the output of a thermocouple (which has a limited rate of change) is inherently bandlimited. Nevertheless, these signals can still contain noise and interference components.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com SERIAL INTERFACE The SPI-compatible serial interface consists of either four signals (CS, SCLK, DIN, and DOUT/DRDY), or three signals (in which case CS may be tied low). The interface is used to read conversion data, read and write registers, and control device operation. CHIP SELECT (CS) The chip select (CS) selects the ADS1118 for SPI communication. This feature is useful when multiple devices share the same serial bus.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 REGISTERS The ADS1118 has two registers that are accessible via the SPI port. The Conversion register contains the result of the last conversion. The Config register allows the user to change the ADS1118 operating modes and query the status of the devices. Conversion Register The 16-bit Conversion register contains the result of the last conversion in binary twos complement format.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 Bit 8 www.ti.com MODE: Device operating mode This bit controls the ADS1118 operating mode. 0 = Continuous conversion mode 1 = Power-down and single-shot mode (default) Bits[7:5] DR[2:0]: Data rate These bits control the data rate setting.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 DATA RETRIEVAL Data can be written to and read from the ADS1118 in the same manner in single-shot mode as in continuous conversion mode, without having to issue any commands. The mode in which ADS1118 operates in can be selected by the MODE bit in the Config register. Setting the MODE bit to '0' puts the device in continuous conversion mode. In this mode, the device is constantly starting new conversions even when CS is high.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com 16-Bit Data Transmission Cycle If Config register data are not required to be readback, the ADS1118 conversion data can also be clocked out in a short 16-bit data transmission cycle, as shown in Figure 46. Therefore, CS must be taken high after the 16th SCLK cycle. Taking CS high resets the SPI interface. The next time CS is taken low, data transmission starts with the currently buffered conversion result on the first SCLK rising edge.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 APPLICATION INFORMATION The following sections give example circuits and suggestions for using the ADS1118 in various situations. BASIC CONNECTIONS AND LAYOUT CONSIDERATIONS For many applications, connecting the ADS1118 is simple. A basic connection diagram for the ADS1118 is shown in Figure 47. Most microcontroller SPI peripherals can operate with the ADS1118. The interface operates in SPI mode 1 where CPOL = 0 and CPHA = 1.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com TI recommends employing best design practices when laying out a printed circuit board (PCB) for both analog and digital components.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 CONNECTING MULTIPLE DEVICES Connecting multiple ADS1118s to a single bus is simple. SCLK, DIN, and DOUT/DRDY can be safely shared by using a dedicated chip-select (CS) for each SPI-enabled device. By default, when CS goes high for the ADS1118, DOUT/DRDY is pulled up to the supply of the ADS1118 by a weak 400 kΩ resistor.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com USING GPIO PORTS FOR COMMUNICATION Most microcontrollers have programmable input/output (I/O) pins that can be set in software to act as inputs or outputs. If an SPI controller is not available, the ADS1118 can be connected to GPIO pins and the SPI bus protocol can be simulated. Using GPIO pins to generate the SPI interface only requires that the pins be configured as push or pull inputs or outputs.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 THERMOCOUPLE MEASUREMENT WITH COLD JUNCTION COMPENSATION For an independent, two-channel thermocouple system, Figure 51 shows the basic connections. This circuit contains a simple low-pass, anti-aliasing filter, mid-point bias, and open detection.
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ADS1118 SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 www.ti.com The two 1-MΩ resistors (RPU and RPD) serve two purposes. The first purpose is to offer a common-mode bias near midsupply. Although the ADS1118 does offer the ability to float the common-mode of a signal or connect any of the inputs to a common point such as ground or supply, TI generally recommends avoiding such situations.
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ADS1118 www.ti.com SBAS457D – OCTOBER 2010 – REVISED OCTOBER 2013 REVISION HISTORY NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision C (February 2013) to Revision D Page • Deleted device graphic ......................................................................................................................................................... 1 • Changed bit 1 to NOP0 in Table 6 ....................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 18-Oct-2013 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.
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PACKAGE MATERIALS INFORMATION www.ti.com 18-Oct-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing ADS1118IDGSR VSSOP DGS 10 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 2500 330.0 12.4 5.3 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 3.3 1.3 8.0 12.0 Q1 ADS1118IDGST VSSOP DGS 10 250 180.0 12.4 5.3 3.3 1.3 8.0 12.0 Q1 ADS1118IRUGR X2QFN RUG 10 3000 179.0 8.4 1.75 2.25 0.65 4.0 8.
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PACKAGE MATERIALS INFORMATION www.ti.com 18-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS1118IDGSR VSSOP DGS 10 2500 370.0 355.0 55.0 ADS1118IDGST VSSOP DGS 10 250 195.0 200.0 45.0 ADS1118IRUGR X2QFN RUG 10 3000 203.0 203.0 35.0 ADS1118IRUGT X2QFN RUG 10 250 203.0 203.0 35.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.