LM75
Digital Temperature Sensor and Thermal Watchdog with
Two-Wire Interface
General Description
The LM75 is a temperature sensor, Delta-Sigma analog-to-
digital converter, and digital over-temperature detector with
I
2
C
interface. The host can query the LM75 at any time to
read temperature. The open-drain Overtemperature Shut-
down (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
OS
) and the temperature at which the alarm condition goes
away (T
HYST
). In addition, the host can read back the con-
tents of the LM75's T
OS
and T
HYST
registers. Three pins (A0,
A1, A2) are available for address selection. The sensor
powers up in Comparator mode with default thresholds of
80C T
OS
and 75C T
HYST
.
The LM75's 3.0V to 5.5V supply voltage range, low supply
current and I
2
C interface make it ideal for a wide range of
applications. These include thermal management and pro-
tection applications in personal computers, electronic test
equipment, and office electronics.
Features
n
SOP-8 and Mini SOP-8 (MSOP) packages save space
n
I
2
C Bus interface
n
Separate open-drain output pin operates as interrupt or
comparator/thermostat output
n
Register readback capability
n
Power up defaults permit stand-alone operation as
thermostat
n
Shutdown mode to minimize power consumption
n
Up to 8 LM75s can be connected to a single bus
n
UL Recognized Component
Key Specifications
j
Supply Voltage
3.0V to 5.5V
j
Supply Current
operating
250 A (typ)
1 mA (max)
shutdown
4 A (typ)
j
Temperature Accuracy
-25C to 100C
2C(max)
-55C to 125C
3C(max)
Applications
n
System Thermal Management
n
Personal Computers
n
Office Electronics
n
Electronic Test Equipment
Simplified Block Diagram
01265801
I2C
is a registered trademark of Philips Corporation.
February 2004
LM75
Digital
T
emperature
Sensor
and
Thermal
W
atchdog
with
T
wo-W
ire
Interface
2004 National Semiconductor Corporation
DS012658
www.national.com
Connection Diagram
SOP-8 and Mini SOP-8
01265802
Ordering Information
Order Number
Package
Marking
NS Package
Number
Supply
Voltage
Transport Media
Noise Filter
on SDA and
SCL
LM75BIM-3
LM75BIM-3
M08A (SOP-8)
3.3V
95 Units in Rail
Yes
LM75BIMX-3
LM75BIM-3
M08A (SOP-8)
3.3V
2500 Units on Tape and Reel
Yes
LM75BIMM-3
T01B
MUA08A (MSOP-8)
3.3V
1000 Units on Tape and Reel
Yes
LM75BIMMX-3
T01B
MUA08A (MSOP-8)
3.3V
3500 Units on Tape and Reel
Yes
LM75BIM-5
LM75BIM-5
M08A (SOP-8)
5V
95 Units in Rail
Yes
LM75BIMX-5
LM75BIM-5
M08A (SOP-8)
5V
2500 Units on Tape and Reel
Yes
LM75BIMM-5
T00B
MUA08A (MSOP-8)
5V
1000 Units on Tape and Reel
Yes
LM75BIMMX-5
T00B
MUA08A (MSOP-8)
5V
3500 Units on Tape and Reel
Yes
LM75CIM-3
LM75CIM-3
M08A (SOP-8)
3.3V
95 Units in Rail
Not Available
LM75CIMX-3
LM75CIM-3
M08A (SOP-8)
3.3V
2500 Units on Tape and Reel
Not Available
LM75CIMM-3
T01C
MUA08A (MSOP-8)
3.3V
1000 Units on Tape and Reel
Not Available
LM75CIMMX-3
T01C
MUA08A (MSOP-8)
3.3V
3500 Units on Tape and Reel
Not Available
LM75CIM-5
LM75CIM-5
M08A (SOP-8)
5V
95 Units in Rail
Not Available
LM75CIMX-5
LM75CIM-5
M08A (SOP-8)
5V
2500 Units on Tape and Reel
Not Available
LM75CIMM-5
T00C
MUA08A (MSOP-8)
5V
1000 Units on Tape and Reel
Not Available
LM75CIMMX-5
T00C
MUA08A (MSOP-8)
5V
3500 Units on Tape and Reel
Not Available
Pin Description
Label
Pin #
Function
Typical Connection
SDA
1
I
2
C Serial Bi-Directional Data Line. Open Drain.
From Controller, tied to a pull-up
SCL
2
I
2
C Clock Input
From Controller
O.S.
3
Overtemperature Shutdown Open Drain Output
Pullup Resistor, Controller Interrupt Line
GND
4
Power Supply Ground
Ground
+V
S
8
Positive Supply Voltage Input
DC Voltage from 3V to 5.5V; 0.1F bypass
capacitor with 10F bulk capacitance in the
near vicinity
A0A2
7,6,5
User-Set I
2
C Address Inputs
Ground (Low, "0") or +V
S
(High, "1")
LM75
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2
Pin Description
(Continued)
01265803
FIGURE 1. Typical Application
LM75
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3
Absolute Maximum Ratings
(Note 1)
Supply Voltage
-0.3V to 6.5V
Voltage at any Pin
-0.3V to +V
S
+ 0.3V
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
-65C to +150C
Soldering Information, Lead Temperature
SOP and MSOP Package (Note 3)
Vapor Phase (60 seconds)
Infrared (15 seconds)
215C
220C
ESD Susceptibility (Note 4)
LM75B
LM75C
Human Body Model
2500V
1500V
Machine Model
250V
100V
Operating Ratings
Specified Temperature Range
T
MIN
to T
MAX
(Note 5)
-55C to +125C
Supply Voltage Range (+V
S
)
+3.0V to +5.5V
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for +V
S
= +5 Vdc for LM75BIM-5, LM75BIMM-5, LM75CIM-5, and
LM75CIMM-5 and +V
S
= +3.3 Vdc for LM75BIM-3, LM75BIMM-3, LM75CIM-3, and LM75CIMM-3 (Note 6). Boldface limits
apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C, unless otherwise noted.
Parameter
Conditions
Typical
(Note 12)
Limits
(Note 7)
Units
(Limit)
Accuracy
T
A
= -25C to +100C
2.0
C (max)
T
A
= -55C to +125C
3.0
C (max)
Resolution
9
Bits
Temperature Conversion Time
(Note 8)
100
ms
Quiescent Current
LM75B
I
2
C Inactive
0.25
0.5
mA (max)
Shutdown Mode, +V
S
= 3V
4
A
Shutdown Mode, +V
S
= 5V
6
A
LM75C
I
2
C Inactive
0.25
1.0
mA (max)
Shutdown Mode, +V
S
= 3V
4
A
Shutdown Mode, +V
S
= 5V
6
A
O.S. Output Saturation Voltage
I
OUT
= 4.0 mA
0.8
V (max)
(Note 9)
O.S. Delay
(Note 10)
1
Conversions (min)
6
Conversions (max)
T
OS
Default Temperature
(Note 11)
80
C
T
HYST
Default Temperature
(Note 11)
75
C
Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for +V
S
= +5 Vdc for LM75BIM-5,
LM75BIMM-5, LM75CIM-5, and LM75CIMM-5 and +V
S
= +3.3 Vdc for LM75BIM-3, LM75BIMM-3, LM75CIM-3, and
LM75CIMM-3 (Note 6). Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C, unless otherwise
noted.
Symbol
Parameter
Conditions
Typical
(Note 12)
Limits
(Note 7)
Units
(Limit)
V
IN(1)
Logical "1" Input Voltage
+V
S
x 0.7
V (min)
+V
S
+ 0.5
V (max)
V
IN(0)
Logical "0" Input Voltage
-0.3
V (min)
+V
S
x 0.3
V (max)
I
IN(1)
Logical "1" Input Current
V
IN
= 5V
0.005
1.0
A (max)
I
IN(0)
Logical "0" Input Current
V
IN
= 0V
-0.005
-1.0
A (max)
C
IN
All Digital Inputs
20
pF
I
OH
High Level Output Current
V
OH
= 5V
100
A (max)
V
OL
Low Level Output Voltage
I
OL
= 3 mA
0.4
V (max)
t
OF
Output Fall Time
C
L
= 400 pF
250
ns (max)
LM75
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4
Logic Electrical Characteristics
(Continued)
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for +V
S
= +5 Vdc for LM75BIM-5,
LM75BIMM-5, LM75CIM-5, and LM75CIMM-5 and +V
S
= +3.3 Vdc for LM75BIM-3, LM75BIMM-3, LM75CIM-3, and
LM75CIMM-3 (Note 6). Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C, unless otherwise
noted.
Symbol
Parameter
Conditions
Typical
(Note 12)
Limits
(Note 7)
Units
(Limit)
I
O
= 3 mA
I
2
C DIGITAL SWITCHING CHARACTERISTICS Unless otherwise noted, these specifications apply for +V
S
= +5 Vdc for
LM75BIM-5, LM75BIMM-5, LM75CIM-5, and LM75CIMM-5 and +V
S
= +3.3 Vdc for LM75BIM-3, LM75BIMM-3, LM75CIM-3,
and LM75CIMM-3. C
L
(load capacitance) on output lines = 80 pF unless otherwise specified. Boldface limits apply for T
A
=
T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C, unless otherwise noted. The switching characteristics of the LM75 fully
meet or exceed the published specifications of the I
2
C bus. The following parameters are the timing relationships between SCL
and SDA signals related to the LM75. They are not the I
2
C bus specifications.
Symbol
Parameter
Conditions
Typical
(Note 12)
Limits
(Note 7)
Units
(Limit)
t
1
SCL (Clock) Period
2.5
s (min)
t
2
Data in Set-Up Time to SCL High
100
ns (min)
t
3
Data Out Stable after SCL Low
0
ns (min)
t
4
SDA Low Set-Up Time to SCL Low (Start Condition)
100
ns (min)
t
5
SDA High Hold Time after SCL High (Stop Condition)
100
ns (min)
t
TIMEOUT
SDA Time Low for Reset of Serial Interface (Note 13)
LM75B
75
325
ms (min)
ms (max)
LM75C
Not
Applicable
01265804
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
I
) at any pin exceeds the power supplies (V
I
<
GND or V
I
>
+V
S
) the current at that pin should be limited to 5 mA. The 20 mA
maximum package input current rating limits the number of pins that can safely exceedthe power supplies with an input current of 5 mA to four.
Note 3: See AN-450 "Surface Mounting Methods and Their Effect on Product Reliability" or the section titled "Surface Mount" found in a current National
Semiconductor Linear Data Book for other methods of soldering surface mount devices.
Note 4: Human body model, 100 pF discharged through a 1.5 k
resistor. Machine model, 200 pF discharged directly into each pin.
LM75
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5
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