ANALOG DEVICES AD7150 Service Manual

DIGITAL

FILTER

SERIAL

INTERFACE

C

IN1

C

SENS1

EXC1

«- CDC

C

SENS2

C

IN2

EXC2

MUX

EXCITATION

THRESHOLD

THRESHOLD

SCL

V

DD

GND

AD7150

SDA

OUT1

OUT2

CLOCK

GENERATOR

Features

Ultralow power: 3.3 V, 100 • μA

Response time: 10 ms•

Adaptive environmental •
compensation

2 independent capacitance •
input channels

•

Sensor capacitance (C
0 pF up to 13 pF

•

Sensitivity to 1 fF

EMC tested•

AEC-Q100 qualified•

2 modes of operation:•

•

Standalone with fixed settings

Interfaced to a • μC for user-
defined settings

2 proximity detection •
output flags

2-wire serial interface •

2

C-compatible)

(I

Operating temperature: •

−40°C to +85°C

10-lead MSOP package•

Applications

Smart entry systems•

Remote detection•

Contactless switches•

Level switches•

SENS

):

AD7150 Capacitance Converter

for Proximity Sensing

Addresses Power and Sensitivity Requirements

Problem

Discrete sensors have a history of being expensive and difficult to implement. These con­straints often prevent designers from adding sensing functions to their system designs due
to cost and excessive power consumption.

Solution

Leveraging ADI’s established capacitance technology, the new AD7150 for sensor systems
delivers a complete signal processing solution for proximity sensors. This new device offers
important features such as electromagnetic compatibility, adaptive environmental calibration,
small package, low power consumption, and fast response time. Unlike existing solutions
that use potentially unreliable and power hungry optical sensors, the AD7150 consumes just
100 μA, resulting in a 70% power savings.

The AD7150 has undergone extensive EMC evaluation, making it particularly suitable for
use in the harsh environments of today’s demanding automotive applications. In addition,
ADI’s patented front-end architecture makes the AD7150 tolerant of input parasitic ground
capacitance, leakage currents, and power supply noise. This capability greatly enhances
the implementation of robust and highly sensitive proximity sensor systems that provide
consistent detection every time.

The proximity sensor system is further enhanced by the on-chip adaptive environmental
calibration feature. This feature enables the device to automatically recalibrate and adapt
to capacitance changes due to shifts in environmental conditions, such as temperature,
humidity, and the gradual buildup of dust and dirt.

The AD7150 is specified over the –40°C to +85°C temperature range and communicates
over an I
priced at $1.35 in 1000 unit quantities. Automotive models are available.

www.analog.com/cdc

2

C®-compatible 2-wire serial interface. The AD7150 is available in 10-lead MSOP,

High Precision Capacitance-to-Digital Converters (CDCs)

COMPONENTS

DATA

DIGITAL

PROCESSING

ε

R

COMPENSATION

LEVEL ≈

C

1

C

2

C ≈ ε0 ε

R

a ò b

d

C2 ~ REF

C

1

~ LEVEL

CDC

GROUND

(SHIELDING)

SENSOR

(ELECTRODES

INSIDE PCB)

Analog Devices offers a range of integrated capacitive sensing solutions suitable for industrial, instrumentation, medical, and
automotive applications.

Application Focus: Level Sensing

Capacitance level sensors are finding more popularity in a wide range of applications due to their ability to not only measure fluid
level, but to also measure changes in the fluid consistency by detecting changes in the relative permittivity. The AD7746 is a 24-bit
measurement solution that provides continuous high precision level measurement over the entire sensor range. The AD7152 is a
12-bit measurement solution similar to the AD7746. It is suitable for applications where precision can be traded against cost.
The AD7150 can be used as a level switch, providing an on/off threshold, and is the most cost-effective solution for level sensing.

Applications

Proximity sensing•

Dew point sensing•

Pressure measurement•

Level measurement/switch•

Position sensing•

Touch sensing•

Humidity sensing•

Rain sensing•

Impurity detection•

Flow sensing•

Analog Devices, Inc.
Worldwide Headquarters

Analog Devices, Inc.
One Technology Way
P.O. Box 9106
Norwood, MA 02062-9106
U.S.A.
Tel: [phone]
(800.262.5643,
U.S.A. only)
Fax: [phone]

Precision CDCs

Part
Number

AD7150 12 100 2

AD7151 12 100 1

AD7152 12 200 2

AD7153 12 200 1

AD7745 24 90 1

AD7746 24 90 2

AD7747 24 45.5 1

Resolution

(Bits)

Throughput

Rate (SPS)

Number of

Channels

Supply

Voltage (V)

2.7 to 3.6
(single)

2.7 to 3.6
(single)

2.7 to 3.6
(single)

2.7 to 3.6
(single)

2.7 to 5.25
(single)

2.7 to 5.25
(single)

2.7 to 5.25
(single)

Maximum Power
Dissipation (mW)

Input Base

Capacitance

Max (pF)

0.43 10 4

0.3 10 4

0.43 10

0.43 10

4.25 17

4.25 17

4.25 17

Range

C

IN

(pF)

±2

±2

±4

±4

±8

Package

10-lead

MSOP

10-lead

MSOP

10-lead

MSOP

10-lead

MSOP

16-lead

TSSOP

16-lead

TSSOP

16-lead

TSSOP

Price
@ 1k

($U.S.)

1.35

1.35

1.95

1.75

4.60

4.95

4.60

Analog Devices, Inc.
Europe Headquarters

Analog Devices, Inc.
Wilhelm-Wagenfeld-Str. 6
80807 Munich
Germany
Tel: [phone]
Fax: [phone]

Analog Devices, Inc.
Japan Headquarters

Analog Devices, KK
New Pier Takeshiba
South Tower Building
1-16-1 Kaigan, Minato-ku,
Tokyo, 105-6891
Japan
Tel: [phone]
Fax: [phone]

Analog Devices, Inc.
Southeast Asia
Headquarters

Analog Devices
22/F One Corporate Avenue
222 Hu Bin Road
Shanghai, 200021
China
Tel: [phone]
Fax: [phone]

©2008 Analog Devices, Inc. All rights reserved.
Trademarks and registered trademarks are the property
of their respective owners.
Printed in the U.S.A.

PH07504-2-6/08(A)

www.analog.com/cdc