Analog Devices AD7314ARM Datasheet

Low-Voltage, 10-Bit Digital Temperature

AD7314

BANDGAP

TEMPERATURE

SENSOR

SERIAL

BUS

INTERFACE

GND

ID

V

DD

CE
SCLK
SDI
SDO

10-BIT

ANALOG/DIGITAL

CONVERTER

TEMPERATURE

VALUE

REGISTER

a

FEATURES
10-Bit Temperature-to-Digital Converter
–35ⴗC to +85ⴗC Operating Temperature Range
ⴞ2ⴗ C Accuracy
SPI™- and DSP-Compatible Serial Interface
Shutdown Mode
Space-Saving ␮SOIC Package

APPLICATIONS
Hard Disk Drives
Personal Computers
Electronic Test Equipment
Office Equipment
Domestic Appliances
Process Control
Mobile Phones

GENERAL DESCRIPTION

The AD7314 is a complete temperature monitoring system in
an 8-lead µSOIC package. It contains a bandgap temperature
sensor and 10-bit ADC to monitor and digitize the temperature
reading to a resolution of 0.25°C.

The AD7314 has a flexible serial interface that allows easy
interfacing to most microcontrollers. The interface is compat­ible with SPI, QSPI and MICROWIRE™ protocol and is also
compatible with DSPs. The part features a standby mode that
is controlled via the serial interface.

The AD7314’s low supply current and SPI-compatible interface,
make it ideal for a variety of applications, including personal
computers, office equipment, and domestic appliances.

Sensor in 8-Lead ␮SOIC

AD7314

FUNCTIONAL BLOCK DIAGRAM

PRODUCT HIGHLIGHTS

1. The AD7314 has an on-chip temperature sensor that allows
an accurate measurement of the ambient temperature. The
measurable temperature range is –35°C to +85°C, with a
± 2°C temperature accuracy.

2. Supply voltage of 2.65 V to 2.9 V.

3. Space-saving 8-lead µSOIC package.

4. 10-bit temperature reading to 0.25°C resolution.

5. The AD7314 features a standby mode that reduces the
current consumption to 1 µA max.

SPI is a trademark of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corporation.

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Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © Analog Devices, Inc., 2001

1

AD7314–SPECIFICATIONS

(TA = T

Parameter Min Typ Max Unit Test Conditions/Comments

TEMPERATURE SENSOR AND ADC

Accuracy ± 2.0 °CT
Resolution 10 Bits
Update Rate, t

R

Temperature Conversion Time 25 µs

SUPPLIES

Supply Voltage 2.65 2.9 V For Specified Performance
Supply Current

Normal Mode (Inactive) 250 300 µA Part not Converting

Normal Mode (Active) 1 mA Part Converting

Shutdown Mode 1 µA

Power Dissipation 860 µWV

Power Dissipation V

1 sps 3 µW
10 sps 3.3 µW
100 sps 6 µW

DIGITAL INPUT

Input High Voltage, V
Input Low Voltage, V
Input Current, I
Input Capacitance, C

IL

IN

IN

IH

1.85 V VDD = 2.65 V to 2.9 V

DIGITAL OUTPUT

Output High Voltage, V
Output Low Voltage, V
Output Capacitance, C

NOTES

1

All specifications apply for –35°C to +85°C unless otherwise noted.

Specifications subject to change without notice.

OH

OL

OUT

2.4 V I

to T

MIN

, VDD = 2.65 V to 2.9 V, unless otherwise noted.)

MAX

400 µs

0.53 V VDD = 2.65 V to 2.9 V
± 1 µAV
10 pF All Digital Inputs

0.4 V IOL = 200 µA
50 pF

= –35°C to +85°C.

A

= 2.65 V. Using Normal Mode

DD

(Auto Conversion)

= 2.65 V. Using Shutdown Mode

DD

= 0 V to V

IN

SOURCE

= I

SINK

DD

= 200 µA

1, 2

TIMING CHARACTERISTICS

3

(T

= T

to T

A

MIN

, VDD = 2.65 V to 2.9 V, unless otherwise noted. See Figure 1.)

MAX

Parameter Limit Unit Comments

t

1

t

2

t

3

4

t

4

t

5

t

6

t

7

4

t

8

NOTES

1

Guaranteed by design and characterization, not production tested.

2

All input signals are specified with tr = tf = 5 ns (10% to 90% of VDD) and timed from a voltage level of 1.6 V.

3

All specifications apply for –35°C to +85°C unless otherwise noted.

4

Measured with the load circuit of Figure 2.

Specifications subject to change without notice.

0 ns min CE to SCLK Setup Time
50 ns min SCLK High Pulsewidth
50 ns min SCLK Low Pulsewidth
35 ns max Data Access Time After SCLK Rising Edge
20 ns min Data Setup Time Prior to SCLK Falling Edge
0 ns min Data Hold Time After SCLK Falling Edge
0 ns min CE to SCLK Hold Time
40 ns max CE to SDO High Impedance

–2–

REV. 0

CE

WARNING!

ESD SENSITIVE DEVICE

SCLK

SDO

SDI

AD7314

t

1

t

5

t

2

t

t

4

3

t

6

Figure 1. Timing Diagram

t

7

t

8

ABSOLUTE MAXIMUM RATINGS

1

VDD to GND . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V

Digital Input Voltage to GND . . . . . . . –0.3 V to V

Digital Output Voltage to GND . . . . . –0.3 V to V

+ 0.3 V

DD

+ 0.3 V

DD

Operating Temperature Range . . . . . . . . . . . –35°C to +85°C

Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C

Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . 150°C

SOT-23, Power Dissipation . . . . . . . . . . . . . . . . . . . . 450 mW

Thermal Impedance . . . . . . . . . . . . . . . . . . . . 240°C/W

θ

JA

Lead Temperature, Soldering

Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . 215°C

Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C

µSOIC Package, Power Dissipation . . . . . . . . . . . . . . 450 mW

Thermal Impedance . . . . . . . . . . . . . . . . . . . . 206°C/W

θ

JA

Lead Temperature, Soldering

Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . 215°C

Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C

Latch-Up for ID Pin

2

. . . . . . . . . . . . . . . . . . . . . . . . ≤ –70 mA

Latch-Up for All Other Pins . . . . . . . . . . . . . . . . . ≥ –110 mA

NOTES

1

Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.

2

Correct usage of the ID pin will prevent any latch-up occurring. We recommend

that in an application the ID pin should be either tied via a 100 kΩ resistor to V
or left open circuit. If the application complies with our recommendation, the ID
pin will never see –70 mA.

DD

TO

OUTPUT

PIN

50pF

C

L

200␮AI

200␮AI

OL

1.6V

OH

Figure 2. Load Circuit for Data Access Time and Bus
Relinquish Time

ORDERING GUIDE

Temperature Temperature Package Package Branding

Model Range Error Description Option Information

AD7314ARM –35°C to +85°C ± 2°C 8-Lead µSOIC RM-8 CKA

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the AD7314 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.

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–3–