12-Bit Capacitance-to-Digital Converter

Data Sheet

AD7152/AD7153

Rev. A

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FEATURES

Capacitance-to-digital converters

Interfaces to floating sensors

Resolution down to 0.25 fF (that is, up to 12 ENOB)

Linearity: 0.05%

Common-mode (not changing) capacitance up to 5 pF

Four capacitance ranges selectable per operation mode

±0.25 pF to ±2 pF in differential mode

0.5 pF to 4 pF in single-ended mode

Tolerant of parasitic capacitance to ground up to 50 pF

Conversion time per channel: 5 ms, 20 ms, 50 ms, and 60 ms

Internal clock oscillator

Power

2.7 V to 3.6 V single-supply operation

100 μA current consumption

Operating temperature: −40°C to +85°C

10-lead MSOP

APPLICATIONS

Automotive, industrial, and medical systems for

Pressure measurement

Position sensing

Level sensing

Flowmeters

Humidity sensing

FUNCTIONAL BLOCK DIAGRAMS

DIGITAL

FILTER

12-BIT Σ-∆

MODULATOR

CLOCK

GENERATOR

VOLTAGE

REFERENCE

AD7152

SERIAL

INTERFACE

EXCITATION

EXC2

CIN1(+)

CIN1(–)

CIN2(+)

CIN2(–)

EXC1

SDA

SCL

VDD

GND

CONTROL LOGIC

CALIBRATION

CAP+

CAP–

MUX

Figure 1.

DIGITAL

FILTER

12-BIT Σ-∆

MODULATOR

CLOCK

GENERATOR

VOLTAGE

REFERENCE

AD7153

SERIAL

INTERFACE

EXCITATION

CIN1(+)

CIN1(–)

EXC1

SDA

SCL

VDD

GND

CONTROL LOGIC

CALIBRATION

CAP+

CAP–

MUX

Figure 2.

GENERAL DESCRIPTION

The AD7152/AD7153 are 12-bit sigma-delta (Σ-Δ) capacitance-to-

digital converters (CDCs). The capacitance to be measured is

connected directly to the device inputs. The architecture features

inherent high resolution (12-bit no missing codes, up to 12-bit

effective resolution) and high linearity (±0.05%). The AD7152/

AD7153 have four capacitance input ranges per operation mode,

±0.25 pF to ±2 pF in differential mode and 0.5 pF to 4 pF in

single-ended mode.

The AD7152/AD7153 can accept up to 5 pF common-mode

capacitance (not changing), which can be balanced by a

programmable on-chip, digital-to-capacitance converter

(CAPDAC).

The AD7153 has one capacitance input channel, while the

AD7152 has two channels. Each channel can be configured

as single-ended or differential. The AD7152/AD7153 are

designed for floating capacitive sensors.

interface. Both devices can operate with a single power supply

from 2.7 V to 3.6 V. They are specified over the temperature

range of −40°C to +85°C and are available in a 10-lead MSOP.