FM75 Low-Voltage Two-Wire Digital Temperature Sensor with Thermal Alarm
December 2006
FM75
Low-Voltage Two-Wire Digital Temperature Sensor with
Thermal Alarm
Features
■
User Configurable to 9, 10, 11 or 12-bit Resolution
■
Precision Calibrated to ±1°C, 0°C to 100°C
■
■
■
■
tm
Description
The FM75 contains a high-precision CMOS temperature
sensor, a Delta-Sigma analog-to-digital converter, and a
SMBus-compatible serial digital interface. Typical accu-
racy is ±2°C over the full temperature range of 40°C to
125°C and to ±1°C over the range of 0°C to 100°C, with
9- to 12-bit resolution (default is 9).
Thermal alarm output, over-limit signal (OS) supports
interrupt and comparator modes. OS is active if the user-
programmable trip-temperature is exceeded. When the
temperature falls below the trip temperature, plus the
user-programmable hysteresis limit, the OS is disabled.
Available in a surface mount SOIC-8 (SOP-8) package.
Typical
Temperature Range: -40°C to 125°C
Low Operating Current (less than 250µA)
Low Self Heating (0.2°C max. in still air)
Operating Voltage Range: 2.7V to 5.5V
Applications
■
Battery Management
■
FAX Management
■
Printers
■
Portable Medical Instruments
■
HVAC Systems
■
Power Supply Modules
■
Disk Drives
■
Computers
■
Automotive Components
Application Diagram
2.7 to 5.5V
8
A0
User
Programmable
Address
7
6
5
A1
A2
FM75
8-Pin
Configuration
3
OS
SMBus
Interface
SDA
SCL
1
2
4
Figure 1. Typical Application Diagram
Ordering Information
Part Number
FM75M8x
© 2006 Fairchild Semiconductor Corporation
FM75 Rev. 1.0.8
Package
8-Lead SOIC
Temperature Range
-40°C to +125°C
Packing Method
2500 Units, Tape and Reel
www.fairchildsemi.com
FM75 Low-Voltage Two-Wire Digital Temperature Sensor with Thermal Alarm
Pin Assignments
SDA
SCL
OS
GND
1
8
V
DD
A0
A1
A2
2
7
FM75
3
6
4
5
Figure 2. Pin Assignments
Pin Descriptions
Pin #
1
2
3
Name
SDA
SCL
OS
Direction
Input/Output
Input
Output
Description
Serial Data.
Open drain to I/O-data pin for two-wire interface.
Serial Clock.
Clock for two-wire serial interface.
Over-Limit Signal.
Open drain thermostat output that indicates if
the temperature exceeds user-programmable limits. Default is
active LOW.
Ground
Address Least Significant Bits (LSBs).
User selectable address
pins for the three LSBs of the serial interface address.
Supply Voltage
4
5, 6, 7
8
GND
A0, A1, A2
V
DD
Supply
Input
Supply
© 2006 Fairchild Semiconductor Corporation
FM75 Rev. 1.0.8
www.fairchildsemi.com
2
FM75 Low-Voltage Two-Wire Digital Temperature Sensor with Thermal Alarm
Absolute Maximum Ratings
The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed.
The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics
tables are not guaranteed at the absolute maximum ratings. The “Recommended Operating Conditions” table defines
the conditions for actual device operation.
Parameter
Supply Voltage
Output Voltage
Output Current
Storage Temperature Range
Lead Soldering Temperature
ESD
(1)
Human Body Model
Machine Model
Min.
Typ.
Max.
+7
V
CC
+ 0.5
10
Units
V
V
mA
°C
°C
V
V
-60
+150
220
2000
250
Note:
1. Human Body Model: 100pF capacitor discharged through a 1.5kΩ resistor into each pin. Machine Model: 200pF
capacitor discharged directly into each pin.
Electrical Characteristics
(2)
-40°C ð T
A
ð +125°C, V
CC
= 5.0V unless otherwise noted. Specifications are subject to change without notice.
Symbol
T
MIN
, T
MAX
Parameter
Specified Temperature Range
Temperature Conversion Time
(3)
Accuracy
(4)
Conditions
Min.
-40
Typ.
90
Max.
+125
+2
+3
+4
+4
Units
°C
ms
T
A
= +25°C
T
A
= +100°C
T
A
= -40°C (T
MIN
)
T
A
= +125°C (T
MAX
)
-2
-3
-4
-4
°C
Notes:
2. These specifications are guaranteed only for the test conditions listed.
3. This specification only indicates how often temperature information is updated to the temperature register.
The FM75 can be read at any time without interrupting the temperature conversion process.
4. Accuracy (expressed in °C) = the difference between the FM75 output temperature and the measured temperature.
© 2006 Fairchild Semiconductor Corporation
FM75 Rev. 1.0.8
www.fairchildsemi.com
3
FM75 Low-Voltage Two-Wire Digital Temperature Sensor with Thermal Alarm
Logic Electrical Characteristics
Symbol
V
IH
V
IL
V
OL
I
DD
I
DD-SD
I
IN
I
OL
I
LEAK
t
F
C
IN
Parameter
Minimum Input Voltage
Logic HIGH
Maximum Input Voltage
Logic LOW
Maximum Output Voltage
Logic LOW
Quiescent Supply Current
Shutdown Current
Input Leakage Current
Output Sink Current
Output Leakage Current
Output Transition Time
Input Capacitance
Conditions
Min.
V
DD
x 0.7
-0.3
Typ.
Max.
V
DD
+ 0.5
V
DD
x 0.3
0.36
0.36
Units
V
V
V
V
µA
µA
µA
mA
µA
ns
pF
V
DD
= 5V, I
OL
= -3mA
V
DD
= 3V, I
OL
= -1.5mA
Interface Inactive R/W
Activity on SDA
Interface Inactive R/W
Activity on SDA
V
IN
= 0V or 5V, T
A
= 25°C
-40°C < T
A
< 125°C
T
A
= 25°C, V
OL
= 0.4V
V
OH
= 5V, V
DD
= 0V
C
L
= 400pF, I
OL
= -3mA
All Digital Inputs
0.001
250
350
0.15
83
500
700
1
150
±0.1
±1.0
3
5
250
20
© 2006 Fairchild Semiconductor Corporation
FM75 Rev. 1.0.8
www.fairchildsemi.com
4
FM75 Low-Voltage Two-Wire Digital Temperature Sensor with Thermal Alarm
Serial Port Timing
Symbol
t
SCL
t
T:LH
, t
T:HL
t
LOW
t
HIGH
t
BUF
t
SU:DAT
t
HD:DAT
t
HD
t
SU:STA
t
HD:STA
t
SU:STO
t
POR
Parameter
SCL Clock Period
SCL Clock Transition Time
SCL Clock LOW Period
SCL Clock HIGH Period
Bus free time between a Stop and
a new Start Condition
Data In Set-up to SCL HIGH
Data In Hold Time
Data Out Stable after SCL LOW
SCL LOW Set-up to SDA LOW
(Repeated Start Condition)
SCL HIGH Hold after SDA LOW
(Start Condition)
SDA HIGH after SCL HIGH
(Stop Condition)
Time in which a FM75 must be
operational after a power-on reset
Conditions
Min.
1.0
0.470
0.400
1.0
100
100
0
100
100
100
Typ.
Max.
100
300
50
Units
µs
ns
µs
µs
µs
ns
ns
ns
ns
ns
ns
500
ms
t
SCL
SCL
t
HD:STA
t
SU:DAT
t
SU:STA
t
SU:STO
SDA
Data In
t
BUF
t
HD:DAT
t
LOW
t
HIGH
t
T:LH
90%
10%
t
T:HL
SCL
90%
10%
SDA
Data Out
t
HD
Figure 3. Serial Port Timing Diagram
© 2006 Fairchild Semiconductor Corporation
FM75 Rev. 1.0.8
www.fairchildsemi.com
5
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