TEXAS INSTRUMENTS LM 75 SMD Datasheet

LM75 I2C Digital Temperature Sensor and Thermal
Watchdog

February 1996

LM75 I

2

C Digital Temperature Sensor and Thermal Watchdog

General Description

The LM75 is a temperature sensor, Delta-Sigma analog-to­digital converter, and digital over-temperature detector with

2

I

C interface. The host can query the LM75 at any time to
read temperature. The open-drain Overtemperature Shut­down (O.S.) output becomes active when the temperature
exceeds a programmable limit. This pin can operate in ei­ther ‘‘Comparator’’ or ‘‘Interrupt’’ mode.

The host can program both the temperature alarm threshold
(T

) and the temperature at which the alarm condition

OS

goes away (T
contents of the LM75’s T
pins (A0, A1, A2) are available for I

). In addition, the host can read back the

HYST

OS

and T

HYST

2

C address selection.

registers. Three

The sensor powers up in Comparator mode with default
thresholds of 80

The LM75’s 3.0V to 5.5V supply voltage range, low supply
current, and I

CTOSand 75§CT

§

2

C interface make it ideal for a wide range of

HYST

.

applications. These include thermal management and pro­tection applications in personal computers, electronic test
equipment, and office electronics.

Simplified Block Diagram

Features

Y

Tiny SO-8 package saves space (SOT-8 under develop­ment)

Y

I2C Bus interface

Y

Separate open-drain output pin operates as interrupt or
comparator/thermostat output

Y

Register readback capability

Y

Power up defaults permit stand-alone operation as ther­mostat

Y

Shutdown mode to minimize power consumption

Y

Up to 8 LM75s can be connected to a single I2C bus

Key Specifications

Y

Supply Voltage 3.0V to 5.5V

Y

Supply Current operating 250 mA typ

1mAmax

shutdown 1 mA typ

Y

Temperature Accuracyb25§Cto100§Cg2§C(max)

b

55§Cto125§Cg3§C(max)

Applications

Y

System Thermal Management

Y

Personal Computers

Y

Office Electronics

Y

Electronic Test Equipment

C

1996 National Semiconductor Corporation RRD-B30M36/Printed in U. S. A.

TL/H/12658

TL/H/12658– 1

http://www.national.com

Connection Diagrams

SO-8

TL/H/12658– 2

Order Number LM75CIM-3, LM75CIMX-3,

LM75CIM-5 or LM75CIMX-5

See NS Package Number M08A

Ordering Information

Order Number

LM75CIM-3 3.3V

LM75CIMX-3 3.3V 2500 Units on Tape and

LM75CIM-5 5V

LM75CIMX-5 5V 2500 Units on Tape and

Supply

Voltage

Supplied As

Reel

Reel

Pin Description

Label Pin

SDA 1 I2C Serial Bi-Directional Data Line From Controller

SCL 2 I2C Clock Input From Controller

O.S. 3 Overtemperature Shutdown Open Collector Output Pull Up Resistor, Controller Interrupt Line

GND 4 Power Supply Ground Ground

a

V

S

A0–A2 7,6,5 User-Set I2C Address Inputs Ground (Low, ‘‘0’’) oraVS(High, ‘‘1’’)

Ý

8 Positive Supply Voltage Input DC Voltage from 3V to 5.5V

Function Typical Connection

FIGURE 1. Typical Application

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TL/H/12658– 3

Absolute Maximum Ratings (Note 1)

b

Supply Voltage

Voltage at any Pin

b

Input Current at any Pin (Note 2) 5 mA

Package Input Current (Note 2) 20 mA

O.S. Output Sink Current 10 mA

O.S. Output Voltage 6.5V

Storage Temperature

Soldering Information, Lead Temperature
SO Package (Note 3)

Vapor Phase (60 seconds) 215
Infrared (15 seconds) 220

0.3V to 6.5V

0.3V toaV

b

65§Ctoa150§C

a

0.3V

S

ESD Susceptibility (Note 4)

Human Body Model 2.0 kV
Machine Model TBD

Operating Ratings

Specified Temperature Range T

(Note 5)

b

Supply Voltage Range (aVS)

C

§

C

§

to T

MIN

55§Ctoa125§C

a

3.0V toa5.5V

MAX

Temperature-to-Digital Converter Characteristics

Unless otherwise noted, these specifications apply foraV
(Note 6). Boldface limits apply for T

e

e

T

A

J

ea

5 Vdc for LM75CIM-5 andaV

S

T

to T

MIN

; all other limits T

MAX

e

A

Parameter Conditions Typical

Accuracy T

eb

A

eb

T

A

25§Ctoa100§C
55§Ctoa125§C

Resolution 9 Bits

Temperature Conversion Time (Note 8) 100 ms

Quiescent Current I2C Inactive 0.25 mA

2

I

C Active 1.0 mA (max)

Shutdown Mode 1 mA

O.S. Output Saturation Voltage I

e

4.0 mA 0.8

OUT

(Note 9)

O.S. Delay (Note 10) 1 Conversions (min)

TOSDefault Temperature (Note 11) 80

T

Default Temperature (Note 11) 75

HYST

Logic Electrical Characteristics

Unless otherwise noted, these specifications apply foraV

T

; all other limits T

MAX

e

ea

T

A

25 C, unless otherwise noted.

J

ea

5 Vdc. Boldface limits apply for T

S

DIGITAL DC CHARACTERISTICS

Symbol Parameter Conditions Typical

V

V

I

IN(1)

I

IN(0)

C

I

OH

V

t

OF

IN(1)

IN(0)

IN

OL

Logical ‘‘1’’ Input Voltage 2.0 V (min)

Logical ‘‘0’’ Input Voltage 0.8 V (max)

Logical ‘‘1’’ Input Current V

Logical ‘‘0’’ Input Current V

e

5V 0.005 1.0 mA (max)

IN

e

0V

IN

b

0.005

All Digital Inputs 20 pF

High Level Output Current V

Low Level Output Voltage I

Output Fall Time C

e

5V 100 mA (max)

OH

e

3mA 0.4 V (max)

OL

e

400 pF 250

L

e

I

3mA

O

ea

3.3 Vdc for LM75CIM-3

S

ea

T

25 C, unless otherwise noted.

J

Limits Units

(Note 7) (Limit)

g

2.0

g

3.0

C (max)

§

V (max)

6 Conversions (max)

§

§

e

e

T

A

J

Limits Units

(Note 7) (Limit)

b

1.0 mA (max)

C

C

T

MIN

ns (max)

to

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Logic Electrical Characteristics (Continued)

2

I

C DIGITAL SWITCHING CHARACTERISTICS

Unless otherwise noted, these specifications apply for
otherwise specified. Boldface limits apply for T
otherwise noted.

The switching characteristics of the LM75 fully meet or exceed the published specifications of the I
parameters are the timing relationships between SCL and SDA signals related to the LM75. They are not the I
tions.

Symbol Parameter Conditions Typical

t

1

t

2

t

3

t

4

t

5

SCL (Clock) Period 2.5 ms(min)

Data in Set-Up Time to SCL High 100 ns(min)

Data Out Stable after SCL Low 0 ns(min)

SDA Low Set-Up Time to SCL Low (Start Condition) 100 ns(min)

SDA High Hold Time after SCL High (Stop Condition) 100 ns(min)

a

ea

V

5 Vdc, CL(load capacitance) on output linese80 pF unless

S

e

e

T

T

A

J

MIN

to T

; all other limits T

MAX

e

T

A

2

C bus. The following

ea

25§C, unless

J

2

C bus specifica-

Limits Units

(Note 7) (Limit)

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating

the device beyond its rated operating conditions.

Note 2: When the input voltage (V
maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four.

Note 3: See AN-450
Semiconductor Linear Data Book for other methods of soldering surface mount devices.

Note 4: Human body model, 100 pF discharged through a 1.5 kX resistor. Machine model, 200 pF discharged directly into each pin.

Note 5: Thermal resistance of the SO-8 package is 200

Note 6: Both part numbers of the LM75 will operate properly over theaVSsupply voltage range of 3V to 5.5V. The devices are tested and specified for rated

accuracy at their nominal supply voltage. Accuracy will typically degrade 1

Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 8: This specification is provided only to indicate how often temperature data is updated. The LM75 can be read at any time without regard to conversion state

(and will yield last conversion result). If a conversion is in process it will be interrupted and restarted after the end of the read.

Note 9: For best accuracy, minimize output loading. Higher sink currents can affect sensor accuracy with internal heating. This can cause an error of 0.64
rated sink current and saturation voltage based on junction-to-ambient thermal resistance.

Note 10: O.S. Delay is user programmable up to 6 ‘‘over limit’’ conversions before O.S. is set to minimize false tripping in noisy environments.

Note 11: Default values set at power up.

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‘‘Surface Mounting Methods and Their Effect on Product Reliability’’

) at any pin exceeds the power supplies (V

I

C/W, junction-to-ambient when attached to a printed circuit board with 2 oz. foil as shown in

§

k

I

C/V of variation inaVSas it varies from the nominal value.

§

GND or V

l

a

VS) the current at that pin should be limited to 5 mA. The 20 mA

I

or the section titled ‘‘Surface Mount’’ found in a current National

TL/H/12658– 4

Figure 3.

C at full

§

Electrical Characteristics (Continued)

FIGURE 2. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)

TL/H/12658– 5

FIGURE 3. Printed Circuit Board Used for Thermal Resistance Specifications

TL/H/12658– 6

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