Analog Devices AD7814 e Datasheet

10-Bit Digital Temperature Sensor

a

FEATURES
10-Bit Temperature-to-Digital Converter
–55ⴗC to +125ⴗC Operating Temperature Range
ⴞ2ⴗC Accuracy
SPI- and DSP-Compatible Serial Interface
Shutdown Mode
Space-Saving SOT-23 Package

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

GENERAL DESCRIPTION

The AD7814 is a complete temperature monitoring system in a
SOT-23 package or 8-lead MSOP package. It contains a band
gap temperature sensor and 10-bit ADC to monitor and digitize
the temperature reading to a resolution of 0.25°C.

The AD7814 has a flexible serial interface that allows easy inter­facing to most microcontrollers. The interface is compatible
with SPI
compatible with DSPs. The part features a standby mode that is
controlled via the serial interface.

The AD7814’s wide supply voltage range, low supply current,
and SPI-compatible interface make it ideal for a variety of
applications, including personal computers, office equipment,
and domestic appliances.

®

, QSPI™, and MICROWIRE™ protocol, and is also

in 6-Lead SOT-23

AD7814

FUNCTIONAL BLOCK DIAGRAM

BAND GAP

TEMPERATURE

SENSOR

GND

AD7814

INTERFACE

PRODUCT HIGHLIGHTS

1. The AD7814 has an on-chip temperature sensor that allows
an accurate measurement of the ambient temperature. The
measurable temperature range is –55°C to +125°C, with a
± 2°C temperature accuracy.

2. Supply voltage of 2.7 V to 5.5 V

3. Space-saving 6-lead SOT-23 package and 8-lead MSOP
package

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

5. Standby mode that reduces the current consumption to 1 µA

10-BIT

ANALOG/DIGITAL

CONVERTER

TEMPERATURE

VALUE

REGISTER

SERIAL

BUS

V

DD

CS

SCLK
DIN

DOUT

Purchase of licensed I2C components of Analog Devices or one of its sublicensed
Associated Companies conveys a license for the purchaser under the Philips I2C
Patent Rights to use these components in an I2C system, provided that the system
conforms to the I2C Standard Specification as defined by Philips.

REV. E

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. Trademarks and
registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

1

AD7814–SPECIFICATIONS

(TA = T

Parameter Min Typ Max Unit Test Conditions/Comments

TEMPERATURE SENSOR AND ADC

Accuracy ± 2.0 °CT

± 2.0 ± 3.5 °CT
Resolution 10 Bits
Update Rate, t

R

400 µs
Temperature Conversion Time 25 µs

SUPPLIES

Supply Voltage 2.7 5.5 V For Specified Performance
Supply Current

Normal Mode 250 400 µA
Shutdown Mode (V
Shutdown Mode (V

= 5 V) 1.23 3 µA

DD

= 3 V) 0.43 1 µA

DD

Power Dissipation 80 µWV
Power Dissipation V

1 sps 3.7 µW
10 sps 3.9 µW
100 sps 5.8 µW

DIGITAL INPUT

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

DIGITAL OUTPUT

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

NOTES

1

All specifications apply for –55°C to +125°C unless otherwise stated.

2

For VDD = 2.7 V to 3 V and TA = –40°C to +85°C, the typical temperature error is ± 2°C.

3

Guaranteed by design and characterization, not production tested.

Specifications subject to change without notice.

3

IH

IL

IN

IN

3

OH

OL

OUT

2.4 V

VDD – 0.3 V I

to T

MIN

, VDD = 2.7 V to 5.5 V, unless otherwise noted.)

MAX

= 0°C to 85°C. VDD = 3 V to 5.5 V

± 2.5 °CT

A

= –40°C to 0°C. VDD = 3 V to 5.5 V

A

= –55°C to +125°C. VDD = 3 V to 5.5 V

A

DD

DD

0.8 V
± 1 µAV

= 0 V to V

IN

10 pF All Digital Inputs

0.4 V IOL = 200 µA

SOURCE

50 pF

= 3 V. Using Normal Mode
= 3 V. Using Shutdown Mode

DD

= I

= 200 µA

SINK

2

2

TIMING CHARACTERISTICS

1, 2, 3

(TA = T

MIN

to T

, VDD = 2.7 V to 5.5 V, unless otherwise noted.)

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

See Figure 2.

4

Measured with the load circuit of Figure 1.

Specifications subject to change without notice.

0 ns min CS to SCLK Setup Time
50 ns min SCLK High Pulse Width
50 ns min SCLK Low Pulse Width
35 ns max Data Access Time After SCLK Falling Edge
20 ns min Data Setup Time Prior to SCLK Rising Edge
0 ns min Data Hold Time After SCLK Rising Edge
0 ns min CS to SCLK Hold Time

40 ns max CS to DOUT High Impedance

–2–

REV. E

ABSOLUTE MAXIMUM RATINGS*

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 . . . . . . . . . . –55°C to +125°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

MSOP 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

*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.

ORDERING GUIDE

AD7814

200␮A

TO

OUTPUT

PIN

C

L

50pF

200␮A

Figure 1. Load Circuit for Data Access Time and Bus
Relinquish Time

I

OL

1.6V

I

OH

Temperature Temperature Package Package Branding

Model Range Error

1

Description Option Information

AD7814ART-500RL7 –55°C to +125°C ± 2°C 6-Lead SOT-23 RT-6 CAA
AD7814ART-REEL –55°C to +125°C ± 2°C 6-Lead SOT-23 RT-6 CAA
AD7814ART-REEL7 –55°C to +125°C ± 2°C 6-Lead SOT-23 RT-6 CAA
AD7814ARTZ-500RL7
AD7814ARTZ-REEL
AD7814ARTZ-REEL7

2

–55°C to +125°C ± 2°C 6-Lead SOT-23 RT-6 CAA

2

–55°C to +125°C ± 2°C 6-Lead SOT-23 RT-6 CAA

2

–55°C to +125°C ± 2°C 6-Lead SOT-23 RT-6 CAA
AD7814ARM –55°C to +125°C ± 2°C 8-Lead MSOP RM-8 CAA
AD7814ARM-REEL –55°C to +125°C ± 2°C 8-Lead MSOP RM-8 CAA
AD7814ARM-REEL7 –55°C to +125°C ± 2°C 8-Lead MSOP RM-8 CAA
AD7814ARMZ
AD7814ARMZ-REEL

2

–55°C to +125°C ± 2°C 8-Lead MSOP RM-8 CAA

2

–55°C to +125°C ± 2°C 8-Lead MSOP RM-8 CAA
AD7814ARMZ-REEL72–55°C to +125°C ± 2°C 8-Lead MSOP RM-8 CAA

1

Temperature error is over 0°C to 85°C temperature range.

2

Z = Pb-free part

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.

WARNING!

Although the AD7814 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.

ESD SENSITIVE DEVICE

REV. E

–3–