12-Bit

ADC

Σ

Serial

Peripheral

Interface

Voltage

Reference

Oscillator

CS

DIN

SCLK

PGA

Device

AIN1

AIN2

GND

AIN0

AIN3

VDD

Mux

Temperature

Sensor

ADS1018-Q1

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SBAS741A – OCTOBER 2015 – REVISED NOVEMBER 2015

8 Detailed Description

8.1 Overview

The ADS1018-Q1 is a very small, low-power, noise-free, 12-bit, delta-sigma (

ΔΣ) analog-to-digital converter

(ADC). The ADS1018-Q1 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. The Functional Block Diagram

section shows the ADS1018-Q1 functional block diagram.

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 ADS1018-Q1 has two available conversion modes: single-shot and continuous-conversion. 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.

8.2 Functional Block Diagram

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