ANALOG DEVICES ADT75 Service Manual

±1°C Accurate, 12-Bit Digital

T

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FEATURES

12-bit temperature-to-digital converter
B grade accuracy ±1.0°C from 0°C to 70°C
A grade accuracy ±2.0°C from –25°C to +100°C
SMBus/I
Operation from −55°C to +125°C
Operation from 3 V to 5.5 V
Overtemperature indicator
Shutdown mode for low power consumption
Power consumption 79 μW typically at 3.3 V
Small, low cost 8-pin MSOP in Pb-Sn and Pb-free packages
Standard 8-pin SOIC Pb-free package

APPLICATIONS

Isolated sensors
Environmental control systems
Computer thermal monitoring
Thermal protection
Industrial process control
Power-system monitors
Hand-held applications

2

C-compatible interface

TEMPERATURE

GENERATION

7

A0

6

A1

5

A2

SENSOR

REFERENCE

CLK AND

TIMING

FUNCTIONAL BLOCK DIAGRAM

DECIMATOR

+

–

Σ-Δ

1-BIT

DAC

SMBus/I

V

DD
8

LPF

1-BIT

POINTER

REGISTER

2

C INTERFACE

8

GND

Figure 1.

Temperature Sensor

PRODUCT HIGHLIGHTS

1. On-chip temperature sensor allows an accurate

measurement of the ambient temperature. The measurable
temperature range is −55°C to +125°C.

2. S

upply voltage is 3.0 V to 5.5 V.

3. S

pace-saving, 8-lead MSOP and 8-lead SOIC.

4. T

emperature accuracy is ±1°C maximum.

5. T

emperature resolution is 0.0625°C.

6. Sh

utdown mode reduces the current consumption to

3 A typical.

onnect up to eight ADT75s to a single SMBus/I

7. C

DIGITAL

12-BIT

COMPARATOR

TEMPERATURE

SENSOR

REGISTER

CONFIGURATION

REGISTER

T

SETPOINT

HYST

REGISTER

TOS SETPOINT

REGISTER

3

OS/ALER

1

SDA

2

SCL

05326-001

ADT75

2

C bus.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. 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] © 2005 Analog Devices, Inc. All rights reserved.

ADT75

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TABLE OF CONTENTS

Features.............................................................................................. 1

Temperature Data Format......................................................... 11

Applications....................................................................................... 1

Product Highlights ........................................................................... 1

Functional Block Diagram .............................................................. 1

General Description ......................................................................... 3

Specifications..................................................................................... 4

A Grade.......................................................................................... 4

B Grade .......................................................................................... 5

Timing Specifications and Diagram .......................................... 6

Absolute Maximum Ratings............................................................ 7

ESD Caution.................................................................................. 7

Pin Configuration and Function Descriptions............................. 8

Typical Performance Characteristics ............................................. 9

Theory of Operation ...................................................................... 10

Circuit Information.................................................................... 10

Converter Details........................................................................ 10

One-Shot Mode .......................................................................... 12

Fault Queue................................................................................. 12

Registers....................................................................................... 13

Serial Interface............................................................................ 16

Writing data ................................................................................ 17

Reading Data............................................................................... 18

OS/ALERT Output Overtemperature Modes ........................ 19

SMBus Alert................................................................................ 20

Application Information................................................................ 21

Thermal Response Time ........................................................... 21

Self-Heating Effects.................................................................... 21

Supply Decoupling..................................................................... 21

Temperature Monitoring........................................................... 22

Outline Dimensions....................................................................... 23

Ordering Guide .......................................................................... 23

Functional Description.............................................................. 10

REVISION HISTORY

10/05—Revision O: Initial Version

Rev. 0 | Page 2 of 24

ADT75

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GENERAL DESCRIPTION

The ADT75 is a complete temperature monitoring system in 8-lead
MSOP and SOIC packages. It contains a bandgap temperature sen­sor and 12-bit ADC to monitor and digitize the temperature to a
resolution of 0.0625°C. The ADT75 is pin and register compatible
with the LM75 and AD7416.

The ADT75 is guaranteed to operate at supply voltages from 3 V

o 5.5 V. Operating at 3.3 V, the average supply current is typically

t
200 A.

The ADT75 offers a shutdown mode that powers down the
de

vice and gives a shutdown current of typically 3 A. The
ADT75 is rated for operation over the –55°C to +125°C
temperature range.

Pin A0, Pin A1, and Pin A2 are available for address selection. The
OS/ALER
temperature exceeds a programmable limit. The OS/ALERT pin
can operate in either comparator or interrupt mode.

T pin is an open-drain output that becomes active when

Rev. 0 | Page 3 of 24

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SPECIFICATIONS

A GRADE

TA = T

Table 1.

Parameter Min Typ Max Unit Test Conditions/Comments

TEMPERATURE SENSOR AND ADC

OS/ALERT OUTPUT (OPEN DRAIN)

DIGITAL INPUTS

DIGITAL OUTPUT (OPEN DRAIN)

POWER REQUIREMENTS

to T

MIN

Accuracy at VDD = 3.0 V to 5.5 V ±2 °C TA = −25°C to +100°C
±3 °C TA = −55°C to +100°C
Accuracy at VDD = 3.0 V to 3.6 V ±3 °C TA = +100°C to +125°C
Accuracy at VDD = 4.5 V to 5.5 V ±2 °C TA = +100°C to +125°C
ADC Resolution 12 Bits
Temperature Resolution 0.0625 °C
Temperature Conversion Time 60 ms
Update Rate 100 ms Conversion started every 100 ms
Long Term Drift 0.08 °C Drift over 10 years, if part is operated at 55°C
Temperature Hysteresis +0.03 °C Temperature cycle = 25°C to 125°C to 25°C

Output Low Voltage, VOL 0.4 V IOL = 3 mA
Pin Capacitance 10 pF
High Output Leakage Current, IOH 0.1 5 μA OS/ALERT pin pulled up to 5.5 V
RON Resistance (Low Output) 15 Ω Supply and temperature dependent

Input Current ±1 μA VIN = 0 V to VDD
Input Low Voltage, VIL 0.3 × VDD V
Input High Voltage, VIH 0.7 × VDD V
SCL, SDA Glitch Rejection 50 ns

Pin Capacitance 3 10 pF

Output High Current, I
Output Low Voltage, VOL 0.4 V IOL = 3 mA
Output High Voltage, VOH 0.7 × VDD V
Output Capacitance, C

Supply Voltage 3 5.5 V
Supply Current at 3.3 V 350 500 μA

Supply Current at 5.0 V 380 525 μA

Average Current at 3.3 V 200 μA Part converting and I2C interface inactive
Average Current at 5.0 V 225 μA Part converting and I2C interface inactive
Shutdown Mode at 3.3 V 3 8 μA Supply current in shutdown mode
Shutdown Mode at 5.0 V 5.5 12 μA Supply current in shutdown mode
Average Power Dissipation 798.6 μW VDD = 3.3 V, normal mode at 25°C

1 SPS 78.6 μW

140 μW

, VDD = 3.0 V to 5.5 V. All specifications for −55°C to +125°C, unless otherwise noted.

MAX

Input filtering suppresses n
than 50 ns

OH

OUT

1 mA VOH = 5 V

3 10 pF

Peak current while converting and I
inactive

Peak current while converting and I
inactive

Average power dissipated for V
mode at 25°C

Average power dissipated for V
mode at 25°C

oise spikes of less

2

C interface

2

C interface

= 3.3 V, shutdown

DD

= 5.0 V, shutdown

DD

Rev. 0 | Page 4 of 24

ADT75

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B GRADE

TA = T

Table 2.

Parameter Min Typ Max Unit Test Conditions/Comments

TEMPERATURE SENSOR AND ADC

OS/ALERT OUTPUT (OPEN DRAIN)

DIGITAL INPUTS

DIGITAL OUTPUT (OPEN DRAIN)

POWER REQUIREMENTS

to T

MIN

Accuracy at VDD = 3.0 V to 5.5 V ±1 °C TA = 0°C to +70°C
±2 °C TA = −25°C to +100°C
±3 °C TA = −55°C to +100°C
Accuracy at VDD = 3.0 V to 3.6 V ±3 °C TA = +100°C to +125°C
Accuracy at VDD = 4.5 V to 5.5 V ±2 °C TA = +100°C to +125°C
ADC Resolution 12 bits
Temperature Resolution 0.0625 °C
Temperature Conversion Time 60 ms
Update Rate 100 ms Conversion started every 100 ms
Long Term Drift 0.08 °C Drift over 10 years, if part is operated at 55°C
Temperature Hysteresis +0.03 °C Temperature cycle = 25°C to 125°C to 25°C

Output Low Voltage, VOL 0.4 V IOL = 3 mA
Pin Capacitance 10 pF
High Output Leakage Current, IOH 0.1 5 μA OS/ALERT pin pulled up to 5.5 V
RON Resistance (Low Output) 15 Ω Supply and temperature dependent

Input Current ±1 μA VIN = 0 V to VDD
Input Low Voltage, VIL 0.3 × VDD V
Input High Voltage, VIH 0.7 × VDD V
SCL, SDA Glitch Rejection 50 ns

Pin Capacitance 3 10 pF

Output High Current, I
Output Low Voltage, VOL 0.4 V IOL = 3 mA
Output High Voltage, VOH 0.7 × VDD V
Output Capacitance, C

Supply Voltage 3 5.5 V
Supply Current at 3.3 V 350 500 μA

Supply Current at 5.0 V 380 525 μA

Average Current at 3.3 V 200 μA Part converting and I2C interface inactive
Average Current at 5.0 V 225 μA Part converting and I2C interface inactive
Shutdown Mode at 3.3 V 3 8 μA Supply current in shutdown mode
Shutdown Mode at 5.0 V 5.5 12 μA Supply current in shutdown mode
Average Power Dissipation 798.6 μW VDD = 3.3 V, normal mode at 25°C

1 SPS 78.6 μW

140 μW

, VDD = 3.0 V to 5.5 V. All specifications for −55°C to +125°C, unless otherwise noted.

MAX

Input filtering suppresses n
than 50 ns

OH

OUT

1 mA VOH = 5 V

3 10 pF

Peak current while converting and I
interface inactive

Peak current while converting and I
interface inactive

Average power dissipated for V
mode at 25°C

Average power dissipated for V
mode at 25°C

oise spikes of less

2

C

2

C

= 3.3 V, shutdown

DD

= 5.0 V, shutdown

DD

Rev. 0 | Page 5 of 24

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TIMING SPECIFICATIONS AND DIAGRAM

Measure the SDA and SCL timing with the input filters turned on to meet the fast mode I2C specification. Switching off the input filters
improves the transfer rate but has a negative affect on the EMC behavior of the part.

T

= T

MIN

to T

A

Table 3.

Parameter

Serial Clock Period, t1 2.5 μs Fast mode I2C. See Figure 2
Data In Setup Time to SCL High, t2 50 ns See Figure 2
Data Out Stable After SCL Low, t3 0 0.9
Data Out Stable After SCL Low, t3 0 3.45
SDA Low Setup Time to SCL Low (Start Condition), t4 50 ns See Figure 2
SDA High Hold Time After SCL High (Stop Condition), t5 50 ns See Figure 2
SDA and SCL Rise Time, t6 300 ns Fast mode I2C. See Figure 2
SDA and SCL Rise Time, t6 1000 ns Standard mode I2C. See Figure 2
SDA and SCL Fall Time, t7 300 ns See Figure 2
Capacitive Load for each Bus Line, C

1

Guaranteed by design and characterization; not production tested.

2

This time has to be met only if the master does not stretch the low period of the SCL signal.

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

MAX

1

B

SCL

t

SDA

DATA IN

SDA

DATA OU

MIN TYP MAX Units Comments

2

ns Fast mode I2C. See Figure 2

2

μs Standard mode I2C. See Figure 2

400 pF

t

1

t

4

2

Figure 2. SMBus/I

t

3

2

C Timing Diagram

t

5

t

t

7

6

05326-002

Rev. 0 | Page 6 of 24

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ABSOLUTE MAXIMUM RATINGS

Table 4.

Parameter Rating

VDD to GND –0.3 V to +7 V
SDA Input Voltage to GND –0.3 V to VDD + 0.3 V
SDA Output Voltage to GND –0.3 V to VDD + 0.3 V
SCL Input Voltage to GND –0.3 V to VDD + 0.3 V
OS/ALERT Output Voltage to GND –0.3 V to VDD + 0.3 V
Operating Temperature Range –55°C to +150°C
Storage Temperature Range –65°C to +160°C
Maximum Junction Temperature, T

150.7°C

JMAX

8-Lead MSOP (RM-8)

Power Dissipation1,
Thermal Impedance

2

3

W

= (T

MAX

− TA)/θJA

JMAX

θJA, Junction-to-Ambient (Still Air) 205.9°C/W
θJC, Junction-to-Case 43.74°C/W

8-Lead SOIC (R-8)

Power Dissipation1, 2 W

MAX

= (T

− TA)/θJA

JMAX

Thermal Impedance3

θJA, Junction-to-Ambient (Still Air) 157°C/W
θJC, Junction-to-Case 56°C/W

IR Reflow Soldering

Peak Temperature 220°C (0°C/5°C)
Time at Peak Temperature 10 sec to 20 sec
Ramp-Up Rate 3°C/sec maximum
Ramp-Down Rate –6°C/sec maximum
Time 25°C to Peak Temperature 6 minutes maximum

IR Reflow Soldering (Pb-Free Package)

Peak Temperature 260°C (+0°C)
Time at Peak Temperature 20 sec to 40 sec
Ramp-Up Rate 3°C/sec maximum
Ramp-Down Rate –6°C/sec maximum
Time 25°C to Peak Temperature 8 minutes maximum

1

Values relate to package being used on a standard 2-layer PCB. This gives a

worst case θ
dissipation vs. ambient temperature (T

2

TA = ambient temperature.

3

Junction-to-case resistance is applicable to components featuring a

preferential flow direction, for example, components mounted on a heat
sink. Junction-to-ambient resistance is more useful for air-cooled, PCB­mounted components.

and θJC. Refer to Figure 3 for a plot of maximum power

JA

).

A

Stresses above those listed under Absolute Maximum Ratings
may cause permanent 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.

1.2

1.0

0.8

0.6

0.4

0.2

MAXIMUM POWER DISSIPATION (Watts)

0

–55

–50

–40

–30

Figure 3. MSOP Maximum Power Dissipation vs. Ambient Temperature

MAX PD = 3.4mW AT 150°C

0

102030405060708090

–20

–10

TEMPERATURE (°C)

100

110

120

130

140

150

05326-003

ESD 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 this product 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.

Rev. 0 | Page 7 of 24

ADT75

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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

SDA

Table 5. Pin Function Descriptions

Pin No. Mnemonic Description

1 SDA

SMBus/I

2

C Serial Data Input/Output. Serial data that is loaded into and read from the ADT75 registers is provided

on this pin. Open-drain configuration; needs a pull-up resistor.

2 SCL

Serial Clock Input. This is the clock input for the serial port. The serial clock is used to clock in and clock out data to
and from any register of the ADT75. Open-drain configuration; needs a pull-up resistor.

3 OS/ALERT

Over- and Undertemperature Indicator. Default power as an OS pin. Open-drain configuration; needs a pull-

up resistor.
4 GND
5 A2
6 A1
7 A0
8 V

Positive Supply Voltage, 3 V to 5.5 V. The supply should be decoupled to ground.

DD

Analog and Digital Ground.

SMBus/I2C Serial Bus Address Selection Pin. Logic input. Can be set to GND or VDD.

SMBus/I2C Serial Bus Address Selection Pin. Logic input. Can be set to GND or VDD.

SMBus/I2C Serial Bus Address Selection Pin. Logic input. Can be set to GND or VDD.

1

SCL

OS/ALER

GND

Figure 4. Pin Configuration

ADT75

2

TOP VIEW

3

(Not to Scale)

4

V

8

DD

A0

7
6

A1
A2

5

05326-004

Rev. 0 | Page 8 of 24