Rainbow Electronics LM75 User Manual
October 2002
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
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
OS
away (T
tents of the LM75’s T
A1, A2) are available for address selection. The sensor
powers up in Comparator mode with default thresholds of
80˚C T
The LM75’s 3.0V to 5.5V supply voltage range, low supply
current and I
applications. These include thermal management and protection applications in personal computers, electronic test
equipment, and office electronics.
2
C®interface. The host can query the LM75 at
) and the temperature at which the alarm condition goes
). In addition, the host can read back the con-
HYST
and 75˚C T
OS
2
C interface make it ideal for a wide range of
OS
HYST
and T
.
registers. Three pins (A0,
HYST
Features
n SOP-8 and Mini SOP-8 (MSOP) packages save space
2
n I
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
Key Specifications
j
Supply Voltage 3.0V to 5.5V
j
Supply Current operating 250 µA (typ)
1 mA (max)
shutdown 4 µA (typ)
j
Temperature Accuracy −25˚C to 100˚C
−55˚C to 125˚C
±
2˚C(max)
±
3˚C(max)
Applications
n System Thermal Management
n Personal Computers
n Office Electronics
n Electronic Test Equipment
LM75 Digital Temperature Sensor and Thermal Watchdog with Two-Wire Interface
Simplified Block Diagram
I2C®is a registered trademark of Philips Corporation.
01265801
© 2002 National Semiconductor Corporation DS012658 www.national.com
Connection Diagram
LM75
Ordering Information
SOP-8 and Mini SOP-8
01265802
Order Number
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
Package
Marking
NS Package
Number
Supply
Voltage
Transport Media
Noise Filter
on SDA and
SCL
Pin Description
Label Pin
SDA 1 I
SCL 2 I
O.S. 3 Overtemperature Shutdown Open Drain Output Pull– up Resistor, Controller Interrupt Line
GND 4 Power Supply Ground Ground
+V
S
A0–A2 7,6,5 User-Set I
#
2
C Serial Bi-Directional Data Line. Open Drain. From Controller, tied to a pull-up
2
C Clock Input From Controller
8 Positive Supply Voltage Input DC Voltage from 3V to 5.5V; 0.1µF bypass
2
C Address Inputs Ground (Low, “0”) or +VS(High, “1”)
Function Typical Connection
capacitor with 10µF bulk capacitance in the
near vicinity
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Pin Description (Continued)
LM75
01265803
FIGURE 1. Typical Application
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Absolute Maximum Ratings (Note 1)
LM75
Supply Voltage −0.3V to 6.5V
Voltage at any Pin −0.3V to +V
+ 0.3V
S
ESD Susceptibility (Note 4) LM75B LM75C
Human Body Model 2500V 1500V
Machine Model 250V 100V
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 −65˚C to +150˚C
Operating Ratings
Specified Temperature Range T
(Note 5) −55˚C to +125˚C
Supply Voltage Range (+V
) +3.0V to +5.5V
S
MIN
Soldering Information, Lead Temperature
SOP and MSOP Package (Note 3)
Vapor Phase (60 seconds)
Infrared (15 seconds)
215˚C
220˚C
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for +VS= +5 Vdc for LM75BIM-5, LM75BIMM-5, LM75CIM-5, and
LM75CIMM-5 and +V
apply for T
A=TJ=TMIN
Parameter Conditions
Accuracy T
Resolution 9 Bits
Temperature Conversion Time (Note 8) 100 ms
Quiescent Current LM75B I
O.S. Output Saturation Voltage I
O.S. Delay (Note 10) 1 Conversions (min)
T
Default Temperature (Note 11) 80 ˚C
OS
T
Default Temperature (Note 11) 75 ˚C
HYST
= +3.3 Vdc for LM75BIM-3, LM75BIMM-3, LM75CIM-3, and LM75CIMM-3 (Note 6). Boldface limits
S
to T
LM75C I
; all other limits TA=TJ= +25˚C, unless otherwise noted.
MAX
Typical
(Note 12)
= −25˚C to +100˚C
A
T
= −55˚C to +125˚C
A
2
C Inactive 0.25 0.5 mA (max)
Shutdown Mode, +V
Shutdown Mode, +V
2
C Inactive 0.25 1.0 mA (max)
Shutdown Mode, +V
Shutdown Mode, +V
= 4.0 mA 0.8 V (max)
OUT
=3V 4 µA
S
=5V 6 µA
S
=3V 4 µA
S
=5V 6 µA
S
Limits
(Note 7)
±
2.0 ˚C (max)
±
3.0 ˚C (max)
Units
(Limit)
(Note 9)
6 Conversions (max)
to T
MAX
Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for +VS= +5 Vdc for LM75BIM-5,
LM75BIMM-5, LM75CIM-5, and LM75CIMM-5 and +V
LM75CIMM-3 (Note 6). Boldface limits apply for T
noted.
Symbol Parameter Conditions
V
IN(1)
V
IN(0)
I
IN(1)
I
IN(0)
C
IN
I
OH
V
OL
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Logical “1” Input Voltage +VSx 0.7 V (min)
Logical “0” Input Voltage −0.3 V (min)
Logical “1” Input Current VIN= 5V 0.005 1.0 µA (max)
Logical “0” Input Current VIN= 0V −0.005 −1.0 µA (max)
All Digital Inputs 20 pF
High Level Output Current VOH=5V 100 µA (max)
Low Level Output Voltage IOL=3mA 0.4 V (max)
= +3.3 Vdc for LM75BIM-3, LM75BIMM-3, LM75CIM-3, and
S
A=TJ=TMIN
to T
; all other limits TA=TJ= +25˚C, unless otherwise
MAX
Typical
(Note 12)
Limits
(Note 7)
+V
+ 0.5 V (max)
S
+V
x 0.3 V (max)
S
Units
(Limit)
Logic Electrical Characteristics (Continued)
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for +VS= +5 Vdc for LM75BIM-5,
LM75BIMM-5, LM75CIM-5, and LM75CIMM-5 and +V
LM75CIMM-3 (Note 6). Boldface limits apply for T
noted.
Symbol Parameter Conditions
t
OF
Output Fall Time CL= 400 pF 250 ns (max)
I2C DIGITAL SWITCHING CHARACTERISTICS Unless otherwise noted, these specifications apply for +VS= +5 Vdc for
LM75BIM-5, LM75BIMM-5, LM75CIM-5, and LM75CIMM-5 and +V
and LM75CIMM-3. C
T
J=TMIN
to T
(load capacitance) on output lines = 80 pF unless otherwise specified. Boldface limits apply for TA=
L
; all other limits TA=TJ= +25˚C, unless otherwise noted. The switching characteristics of the LM75 fully
MAX
meet or exceed the published specifications of the I
and SDA signals related to the LM75. They are not the I
Symbol Parameter Conditions
t
1
t
2
t
3
t
4
t
5
t
TIMEOUT
SCL (Clock) Period 2.5 µs (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)
SDA Time Low for Reset of Serial Interface (Note 13) LM75B 75
= +3.3 Vdc for LM75BIM-3, LM75BIMM-3, LM75CIM-3, and
S
A=TJ=TMIN
I
=3mA
O
2
C bus. The following parameters are the timing relationships between SCL
2
C bus specifications.
to T
S
; all other limits TA=TJ= +25˚C, unless otherwise
MAX
Typical
(Note 12)
Limits
(Note 7)
= +3.3 Vdc for LM75BIM-3, LM75BIMM-3, LM75CIM-3,
Typical
(Note 12)
Limits
(Note 7)
325
LM75C Not
Applicable
LM75
Units
(Limit)
Units
(Limit)
ms (min)
ms (max)
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
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 kΩ resistor. Machine model, 200 pF discharged directly into each pin.
) at any pin exceeds the power supplies (V
I
<
I
GND or V
>
+VS) the current at that pin should be limited to 5 mA. The 20 mA
I
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Note 5: LM75 θJA(thermal resistance, junction-to-ambient) when attached to a printed circuit board with 2 oz. foil similar to the one shown in Figure 3 is summarized
in the table below:
LM75
Device Number
NS Package
Number
Thermal
Resistance (θ
)
JA
LM75BIM-3, LM75BIM-5, LM75CIM-3, LM75CIM-5 M08A 200˚C/W
LM75BIMM-3, LM75BIMM-5, LM75CIMM-3, LM75CIMM-5 MUA08A 250˚C/W
Note 6: All part numbers of the LM75 will operate properly over the +VSsupply 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˚C/V of variation in +V
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˚C at full
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.
Note 12: Typicals are at T
Note 13: Holding the SDA line low for a time greater than t
High).
= 25˚C and represent most likely parametric norm.
A
will cause the LM75B to reset SDA to the IDLE state of the serial bus communication (SDA set
TIMEOUT
as it varies from the nominal value.
S
FIGURE 2. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)
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01265805
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