ADS1118_13 Datasheet, PDF (13/38 Pages) Texas Instruments – Ultra-Small, Low-Power, SPI™-Compatible, 16-Bit Analog-to-Digital Converter and Temperature Sensor with Internal Reference

ADS1118
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OVERVIEW
SBAS457C – OCTOBER 2010 – REVISED FEBRUARY 2013
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.
The ADS1118 consists of a ΔΣ ADC core with adjustable gain, an internal voltage reference, a clock oscillator,
and an SPI. This device is also a highly linear and accurate temperature sensor. All of these features are
intended to reduce required external circuitry and improve performance. Figure 38 shows the ADS1118
functional block diagram.
VDD
Device
AIN0
MUX
AIN1
AIN2
AIN3
Gain = 2/3, 1,
2, 4, 8, or 16
Voltage
Reference
PGA
16-Bit DS
ADC
SPI
Interface
Oscillator
Temperature
Sensor
CS
SCLK
DIN
DOUT/DRDY
GND
Figure 38. ADS1118 Functional Block Diagram
The ADS1118 ADC core measures a differential signal, V_IN, that is the difference of AIN_P and AIN_N. The
converter core consists of a differential, switched-capacitor ΔΣ modulator followed by a digital filter. This
architecture results in a very strong attenuation in any common-mode signals. Input signals are compared to the
internal voltage reference. The digital filter receives a high-speed bitstream from the modulator and outputs a
code proportional to the input voltage.
The ADS1118 has two available conversion modes: single-shot mode and continuous conversion mode. In
single-shot mode, the ADC performs one conversion of the input signal upon request and stores the value to an
internal conversion register. The device then enters a power-down state. This mode is intended to provide
significant power savings in systems that require only periodic conversions or when there are long idle periods
between conversions. In continuous conversion mode, the ADC automatically begins a conversion of the input
signal as soon as the previous conversion is completed. The rate of continuous conversion is equal to the
programmed data rate. Data can be read at any time and always reflect the most recently completed conversion.
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