LM74
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LM74 SPI/Microwire12-Bit Plus Sign Temperature Sensor
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FEATURES
DESCRIPTION
•
•
The LM74 is a temperature sensor, Delta-Sigma
analog-to-digital converter with an SPI and
MICROWIRE compatible interface. The host can
query the LM74 at any time to read temperature. A
shutdown mode decreases power consumption to
less than 10 μA. This mode is useful in systems
where low average power consumption is critical.
1
2
•
•
0.0625°C Temperature Resolution
Shutdown Mode Conserves Power Between
Temperature Reading
SPI and MICROWIRE Bus Interface
5-Bump DSBGA Package Saves Space
APPLICATIONS
•
•
•
•
•
System Thermal Management
Personal Computers
Disk Drives
Office Electronics
Electronic Test Equipment
KEY SPECIFICATIONS
•
•
•
Supply Voltage 3.0V or 2.65V to 5.5V
Supply Current
– Operating
– 265μA (typ)
– 520μA (max)
– Shutdown
– 3μA (typ)
Temperature Accuracy
– −10°C to 65°C, ±1.25°C(max)
– −25°C to 110°C, ±2.1°C(max)
– −55°C to 125°C, ±3°C(max)
The LM74 has 12-bit plus sign temperature resolution
(0.0625°C per LSB) while operating over a
temperature range of −55°C to +150°C.
The LM74's 3.0V to 5.5V supply voltage range, low
supply current and simple SPI interface make it ideal
for a wide range of applications. These include
thermal management and protection applications in
hard disk drives, printers, electronic test equipment,
and office electronics. The LM74 is available in the
SOIC package as well as the 5-Bump DSBGA
package.
Block Diagram
Figure 1.
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2000–2013, Texas Instruments Incorporated
LM74
SNIS107K – MAY 2000 – REVISED MARCH 2013
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Connection Diagram
GND (A3)
(B3) CS
SC (A2)
(B1) V+
SI/O (A1)
Figure 2. SOIC – Top View
See Package Number D
Figure 3. 5-Bump DSBGA – Top View
See Package Number YTA0005
PIN DESCRIPTIONS
SOIC
Pin #
DSBGA
Pin #
SI/O
1
1
Slave Input/Output - Serial bus bi-directional data line.
From and to Controller
Schmitt trigger input.
SC
2
5
Slave Clock - Serial bus clock Schmitt trigger input
line.
From Controller
NC
3
No Connection
No Connection
GND
4
Power Supply Ground
Ground
NC
5
No Connection
No Connection
NC
6
No Connection
No Connection
CS
7
Chip Select input.
From Controller
Positive Supply Voltage Input
DC Voltage from 3.0V to 5.5V for the LM74CIM
and 2.65V to 5.5V for the LM74CIBP and
LM74CITP. Bypass with a 0.1 μF ceramic
capacitor.
Label
+
V
8
4
3
2
Function
Typical Connection
Typical Application
+3.3 V
L0(GPI/O)
SI
SK
CS
V+
0.1 µF
SI/O
SC
GND
COP8SA
MicroController
Figure 4. COP Microcontroller Interface
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
2
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Absolute Maximum Ratings (1)
−0.3V to 6.0V
Supply Voltage
−0.3V to V+ + 0.3V
Voltage at any Pin
Input Current at any Pin (2)
5 mA
Package Input Current (2)
20 mA
−65°C to +150°C
Storage Temperature
ESD Susceptibility (3)
Human Body Model
LM74CIBP and LM74CITP, pin A2 (SC)
1900V
LM74CIM,LM74CIBP, and LM74CITP all other pins
2000V
Machine Model
200V
Soldering process must comply with Reflow Temperature Profile specifications. See www.ti.com/packaging.
(1)
(2)
(3)
(4)
(4)
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.
When the input voltage (VI) at any pin exceeds the power supplies (VI < GND or VI > +VS) 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 exceed the power supplies with an input
current of 5 mA to four.
Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin.
Reflow temperature profiles are different for lead-free and non-lead-free packages.
Operating Ratings
Specified Temperature Range
TMIN to TMAX
(1)
See
LM74CIBP and LM74CITP
LM74CIM
−40°C to +125°C
−55°C to +150°C
Supply Voltage Range (+VS)
LM74CIBP and LM74CITP
+2.65V to +5.5V
LM74CIM
(1)
+3.0V to +5.5V
The life expectancy of the LM74 will be reduced when operating at elevated temperatures. LM74 θJA (thermal resistance, junction-toambient) when attached to a printed circuit board with 2 oz. foil is summarized as: Device Number LM74CIM Thermal Resistance (θJA)
160°C/W. Device Number LM74CIBP Thermal Resistance (θJA) 250°C/W. Device Number LM74CITP Thermal Resistance (θJA)
250°C/W.
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Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for V+ = 2.65V to 3.6V for the LM74CIBP -3, LM74CITP-3, V+ = 3.0V to
3.6V for the LM74CIM -3 and V+ = 4.5V to 5.5V for the LM74 -5 (1). Boldface limits apply for TA = TJ = TMIN to TMAX; all other
limits TA = TJ=+25°C, unless otherwise noted.
LM74-3
Limits (3)
Units
(Limit)
±1.25
±1.25
°C (max)
TA = −25°C to +110°C
±2.1
+2.65/−2.15
°C (max)
TA = −40°C to +85°C
+2.65/−1.65
±2.15
°C (max)
TA = −40°C to +110°C
+2.65/
−2.0
+2.65/−2.15
°C (max)
TA = −55°C to +125°C
±3.0
±3.5
°C (max)
TA = −55°C to +150°C
±5.0
±5.0
°C (max)
Conditions
Temperature Error (1)
TA = −10°C to +65°C
Resolution
Temperature
Conversion Time
Quiescent Current
13
280
425
425
ms (max)
DSBGA See (4)
611
925
925
ms (max)
310
520
520
μA (max)
265
470
470
μA (max)
SOIC See
SOIC Serial Bus Inactive
310
μA
310
μA
SOIC Shutdown Mode,
V+ = 3.3V
DSBGA
7
μA
3
μA
SOIC Shutdown Mode,
V+ = 5V
DSBGA
8
μA
4
μA
SOIC Serial Bus Active
DSBGA
(2)
(3)
(4)
4
Bits
(4)
DSBGA
(1)
Typical (2)
LM74-5
Limits (3)
Parameter
All SOP (LM74CIM) parts will function over the V+ supply voltage range of 3V to 5.5V. All DSBGA (LM74SIBP and LM75CITP) parts will
function over the V+ supply voltage range of 2.65V to 5.5V. The SOP (LM74CIM) parts are tested and specified for rated temperature
error at their nominal supply voltage for temperature ranges of −10°C to +65°C, −55°C to +125°C and −55°C to +150°C. For the SOP
(LM74CIM) parts, the temperature error specifications for temperature ranges of −40°C to +85°C, −25°C to +110°C, and −40°C to
+110°C include error induced by power supply variation of ±5% from the nominal value. For the LM74CIM (SOP) parts, the temperature
error will increase by ±0.3°C for a power supply voltage (V+) variation of ±10% from the nominal value.For the LM74CIBP-3 and
LM74CITP-3 (DSBGA) parts all accuracies are ensured over the supply range of 2.65V to 3.6V, except for the temperature ranges of 55°C to 125°C and −55°C to +150°C where the accuracy applies for the nominal supply voltage of 3.3V. For the LM74CIBP-5 and
LM74CITP-5 (DSBGA) parts all accuracies are guranteed over the supply range of 4.75V to 5.25V, except for the temperature ranges of
-55°C to 125°C and −55°C to +150°C where the accuracy applies for the nominal supply voltage of 5.0V. For the LM74CIBP and
LM74CITP over -55°C to 125°C and −55°C to +150°C, a power supply variation of ±10% will degrade the accuracy by ±0.3°C.
Typicals are at TA = 25°C and represent most likely parametric norm.
Limits are specified to AOQL (Average Outgoing Quality Level).
This specification is provided only to indicate how often temperature data is updated. The LM74 can be read at any time without regard
to conversion state (and will yield last conversion result). A conversion in progress will not be interrupted. The output shift register will be
updated at the completion of the read and a new conversion restarted.
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Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS
Unless otherwise noted, these specifications apply for V+ = 2.65V to 3.6V for the LM74CIBP -3, LM74CITP-3, V+ = 3.0V to
3.6V for the LM74CIM -3 and V+ = 4.5V to 5.5V for the LM74 -5 (1). Boldface limits apply for TA = TJ = TMIN to TMAX; all other
limits TA = TJ=+25°C, unless otherwise noted.
Symbol
VIN(1)
VIN(0)
Parameter
Conditions
Typical (2)
Logical “1” Input Voltage
V+ = 3.0V to 3.6V
+
V = 4.5V to 5.5V
Units
(Limit)
V+ × 0.7
V (min)
V+ + 0.3
V (max)
−0.3
V (min)
V+ × 0.3
V (max)
0.8
0.35
V (min)
Logical “0” Input Voltage
Input Hysteresis Voltage
Limits (3)
0.8
0.33
V (min)
IIN(1)
Logical “1” Input Current
VIN = V+
0.005
3.0
μA (max)
IIN(0)
Logical “0” Input Current
VIN = 0V
−0.005
−3.0
μA (min)
CIN
All Digital Inputs
VOH
High Level Output Voltage
IOH = −400 μA
2.4
V (min)
VOL
Low Level Output Voltage
IOL = +2 mA
0.4
V (max)
IO_TRI-STATE
TRI-STATE Output Leakage Current VO = GND
VO = V+
−1
+1
μA (min)
μA
(max)
(1)
(2)
(3)
20
pF
All SOP (LM74CIM) parts will function over the V+ supply voltage range of 3V to 5.5V. All DSBGA (LM74SIBP and LM75CITP) parts will
function over the V+ supply voltage range of 2.65V to 5.5V. The SOP (LM74CIM) parts are tested and specified for rated temperature
error at their nominal supply voltage for temperature ranges of −10°C to +65°C, −55°C to +125°C and −55°C to +150°C. For the SOP
(LM74CIM) parts, the temperature error specifications for temperature ranges of −40°C to +85°C, −25°C to +110°C, and −40°C to
+110°C include error induced by power supply variation of ±5% from the nominal value. For the LM74CIM (SOP) parts, the temperature
error will increase by ±0.3°C for a power supply voltage (V+) variation of ±10% from the nominal value.For the LM74CIBP-3 and
LM74CITP-3 (DSBGA) parts all accuracies are ensured over the supply range of 2.65V to 3.6V, except for the temperature ranges of 55°C to 125°C and −55°C to +150°C where the accuracy applies for the nominal supply voltage of 3.3V. For the LM74CIBP-5 and
LM74CITP-5 (DSBGA) parts all accuracies are guranteed over the supply range of 4.75V to 5.25V, except for the temperature ranges of
-55°C to 125°C and −55°C to +150°C where the accuracy applies for the nominal supply voltage of 5.0V. For the LM74CIBP and
LM74CITP over -55°C to 125°C and −55°C to +150°C, a power supply variation of ±10% will degrade the accuracy by ±0.3°C.
Typicals are at TA = 25°C and represent most likely parametric norm.
Limits are specified to AOQL (Average Outgoing Quality Level).
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SERIAL BUS DIGITAL SWITCHING CHARACTERISTICS
Unless otherwise noted, these specifications apply for V+ = 2.65V to 3.6V for the LM74CIBP -3, LM74CITP-3, V+ = 3.0V to
3.6V for the LM74CIM -3 and V+ = 4.5V to 5.5V for the LM74 -5 (1); CL (load capacitance) on output lines = 100 pF unless
otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = +25°C, unless otherwise
noted.
Symbol
Parameter
Conditions
Typical (2)
Limits (3)
Units
(Limit)
μs (min)
(max)
t1
SC (Clock) Period
0.16
DC
t2
CS Low to SC (Clock) High Set-Up Time
100
ns (min)
t3
CS Low to Data Out (SO) Delay
70
ns (max)
t4
SC (Clock) Low to Data Out (SO) Delay
100
ns (max)
t5
CS High to Data Out (SO) TRI-STATE
200
ns (max)
t6
SC (Clock) High to Data In (SI) Hold Time
50
ns (min)
t7
Data In (SI) Set-Up Time to SC (Clock) High
30
ns (min)
(1)
(2)
(3)
All SOP (LM74CIM) parts will function over the V+ supply voltage range of 3V to 5.5V. All DSBGA (LM74SIBP and LM75CITP) parts will
function over the V+ supply voltage range of 2.65V to 5.5V. The SOP (LM74CIM) parts are tested and specified for rated temperature
error at their nominal supply voltage for temperature ranges of −10°C to +65°C, −55°C to +125°C and −55°C to +150°C. For the SOP
(LM74CIM) parts, the temperature error specifications for temperature ranges of −40°C to +85°C, −25°C to +110°C, and −40°C to
+110°C include error induced by power supply variation of ±5% from the nominal value. For the LM74CIM (SOP) parts, the temperature
error will increase by ±0.3°C for a power supply voltage (V+) variation of ±10% from the nominal value.For the LM74CIBP-3 and
LM74CITP-3 (DSBGA) parts all accuracies are ensured over the supply range of 2.65V to 3.6V, except for the temperature ranges of 55°C to 125°C and −55°C to +150°C where the accuracy applies for the nominal supply voltage of 3.3V. For the LM74CIBP-5 and
LM74CITP-5 (DSBGA) parts all accuracies are guranteed over the supply range of 4.75V to 5.25V, except for the temperature ranges of
-55°C to 125°C and −55°C to +150°C where the accuracy applies for the nominal supply voltage of 5.0V. For the LM74CIBP and
LM74CITP over -55°C to 125°C and −55°C to +150°C, a power supply variation of ±10% will degrade the accuracy by ±0.3°C.
Typicals are at TA = 25°C and represent most likely parametric norm.
Limits are specified to AOQL (Average Outgoing Quality Level).
Figure 5. Data Output Timing Diagram
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Figure 6. TRI-STATE Data Output Timing Diagram
Figure 7. Data Input Timing Diagram
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Electrical Characteristics
0,1001,0110,0000
Output Code
+25°C
0,0001,1001,0000
+0.0625°C
0,0000,0000,0001
Temperature
00,0000,0000,0000
-55°C
0°C
1,1111,1111,1111
-0.0625°C
+150°C
1,1110,0111,0000
-25°C
1,1100,1001,0000
Figure 8. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)
TRI-STATE Test Circuit
Figure 9.
8
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Typical Performance Characteristics
Average Power-On Reset Voltage vs Temperature
Static Supply Current vs Temperature (SOIC)
Figure 10.
Figure 11.
Static Supply Current vs Temperature (DSBGA)
Temperature Error (SOIC)
Figure 12.
Figure 13.
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FUNCTIONAL DESCRIPTION
The LM74 temperature sensor incorporates a band-gap type temperature sensor and 12-bit plus sign ΔΣ ADC
(Delta-Sigma Analog-to-Digital Converter). Compatibility of the LM74's three wire serial interface with SPI and
MICROWIRE allows simple communications with common microcontrollers and processors. Shutdown mode can
be used to optimize current drain for different applications. A Manufacture's/Device ID register identifies the
LM74 as Texas Instruments product.
Power Up and Power Down
When the supply voltage is less than about 1.6V (typical), the LM74 is considered powered down. The LM74
always powers up in a known state. When the supply voltage rises above 1.6V (typical), an internal Power-On
Reset (POR) occurs and the temperature register will then contain a value of 1111 1111 0000 00XX, where XX
indicates undefined values. See Temperature Register (after power-up, before first complete temperature
conversion) diagram for contents after POR but before completion of the first temperature conversion.
The LM74 power-up default condition is continuous conversion mode. After completion of the first full
temperature conversion, the register will contain temperature measurement data in bits D15 (the temperature
data MSB) through D3 (the temperature data LSB). Bit D2 will be fixed high; bits D1 and D0 are undefined. See
Section 1.5.3 for a diagram of the Temperature Regisiter contents after the first complete temperature
conversion. Note that bit D2 represents a complete conversion flag. During POR it is low and, after the first
temperature conversion is complete, it goes high. This bit can be polled to indicate when the POR data in the
Temperature Register has been replaced with valid temperature data.
After the first conversion, and any subsequent conversions, the value in the temperature register does not
change until the completion of the next conversion, at which time the temperature register is updated with the
latest temperature value.
Serial Bus Interface
The LM74 operates as a slave and is compatible with SPI or MICROWIRE bus specifications. Data is clocked
out on the falling edge of the serial clock (SC), while data is clocked in on the rising edge of SC. A complete
transmit/receive communication will consist of 32 serial clocks. The first 16 clocks comprise the transmit phase of
communication, while the second 16 clocks are the receive phase.
When CS is high SI/O will be in TRI-STATE. Communication should be initiated by taking chip select (CS) low.
This should not be done when SC is changing from a low to high state. Once CS is low the serial I/O pin (SI/O)
will transmit the first bit of data. The master can then read this bit with the rising edge of SC. The remainder of
the data will be clocked out by the falling edge of SC. Once the 14 bits of data (one sign bit, twelve temperature
bits and 1 high bit) are transmitted the SI/O line will go into TRI-STATE. CS can be taken high at any time during
the transmit phase. If CS is brought low in the middle of a conversion the LM74 will complete the conversion and
the output shift register will be updated after CS is brought back high.
The receive phase of a communication starts after 16 SC periods. CS can remain low for 32 SC cycles. The
LM74 will read the data available on the SI/O line on the rising edge of the serial clock. Input data is to an 8-bit
shift register. The part will detect the last eight bits shifted into the register. The receive phase can last up to 16
SC periods. All ones must be shifted in order to place the part into shutdown. A zero in any location will take the
LM74 out of shutdown. The following codes should only be transmitted to the LM74:
• 00 hex
• 01 hex
• 03 hex
• 07 hex
• 0F hex
• 1F hex
• 3F hex
• 7F hex
• FF hex
any others may place the part into a Test Mode. Test Modes are used by Texas Instruments to thoroughly test
the function of the LM74 during production testing. Only eight bits have been defined above since only the last
eight transmitted are detected by the LM74, before CS is taken HIGH.
10
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The following communication can be used to determine the Manufacturer's/Device ID and then immediately place
the part into continuous conversion mode. With CS continuously low:
• Read 16 bits of temperature data
• Write 16 bits of data commanding shutdown
• Read 16 bits of Manufacture's/Device ID data
• Write 8 to 16 bits of data commanding Conversion Mode
• Take CS HIGH.
Note that one complete temperature conversion period will have to pass before the LM74 Temperature register
will contain the new temperature data. Until then, it will contain a "stale" temperature (the data that was in the
register before going into shutdown mode).
Temperature Data Format
Temperature data is represented by a 13-bit, two's complement word with an LSB (Least Significant Bit) equal to
0.0625°C:
Temperature
Digital Output
Binary
Hex
+150°C
0100 1011 0000 0111
4B 07h
+125°C
0011 1110 1000 0111
3E 87h
+25°C
0000 1100 1000 0111
0C 87h
+0.0625°C
0000 0000 0000 1111
00 0Fh
0°C
0000 0000 0000 0111
00 07h
−0.0625°C
1111 1111 1111 1111
FF FFh
−25°C
1111 0011 1000 0111
F3 87h
−55°C
1110 0100 1000 0111
E4 87h
Note: The last two bits are TRI-STATE and depicted as one in the table.
The first data byte is the most significant byte with most significant bit first, permitting only as much data as
necessary to be read to determine temperature condition. For instance, if the first four bits of the temperature
data indicate an overtemperature condition, the host processor could immediately take action to remedy the
excessive temperatures.
Shutdown Mode/Manufacturer's ID
Shutdown mode is enabled by writing XX FF to the LM74 as shown in Figure 16c. The serial bus is still active
when the LM74 is in shutdown. Current draw drops to less than 10 μA between serial communications. When in
shutdown mode the LM74 always will output 1000 0000 0000 00XX. This is the manufacturer's/Device ID
information. The first 5-bits of the field (1000 0XXX) are reserved for manufacturer's ID. As mentioned in Section
1.2, writing a zero to the LM74 configuration register will take it out of shutdown mode and place it in conversion
mode. In other words, any valid code listed in Section 1.2 other than XX FF will put it in conversion mode. After
leaving shutdown, but before the first temperature conversion is complete, the temperature register will contain
the last measured temperature which resided in the temperature register before entering shutdown mode. After
the completion of the first conversion, the temperature register will be updated with the new temperature data.
Internal Register Structure
The LM74 has three registers, the temperature register, the configuration register and the manufacturer's/device
identification register. The temperature and manufacturer's/device identification registers are read only. The
configuration register is write only.
Configuration Register
(Selects shutdown or continuous conversion modes):
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Table 1. (Write Only):
D15
D14
D13
D12
D11
D10
D9
D8
X
X
X
X
X
X
X
X
D7
D6
D5
D4
D3
D2
D1
D0
Shutdown
D0–D15 set to XX FF hex enables shutdown mode.
D0–D15 set to 00 00 hex sets Continuous conversion mode.
Note: setting D0-D15 to any other values may place the LM74 into a manufacturer's test mode, upon which the
LM74 will stop responding as described. These test modes are to be used for Texas Instruments production
testing only. See Serial Bus Interface for a complete discussion.
Temperature Register (after power-up, before first complete temperature conversion)
Table 2. (Read Only):
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
X
X
D0–D1: Undefined. TRI-STATE will be output on SI/0.
D2–D15: Power-on Reset (POR) values.
Temperature Register (after completion of first temperature conversion)
Table 3. (Read Only):
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
MSB
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
LSB
1
X
X
D0–D1: Undefined. TRI-STATE will be output on SI/0.
D2: High.
D3–D15: Temperature Data. One LSB = 0.0625°C. Two's complement format.
Manufacturer's Device ID Register
Table 4. (Read Only):
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
X
X
D0–D1: Undefined. TRI-STATE will be output on SI/0.
D2–D15: Manufacturer's/Device ID Data. This register is accessed whenever the LM74 is in shutdown mode.
12
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LM74
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SNIS107K – MAY 2000 – REVISED MARCH 2013
Serial Bus Timing Diagrams
Figure 14. a) Reading Continuous Conversion - Single Eight-Bit Frame
Figure 15. b) Reading Continuous Conversion - Two Eight-Bit Frames
Figure 16. c) Writing Shutdown Control
Application Hints
To get the expected results when measuring temperature with an integrated circuit temperature sensor like the
LM74, it is important to understand that the sensor measures its own die temperature. For the LM74, the best
thermal path between the die and the outside world is through the LM74's pins. In the SOIC package all the pins
on the LM74 will have an equal effect on the die temperature. Because the pins represent a good thermal path to
the LM74 die, the LM74 will provide an accurate measurement of the temperature of the printed circuit board on
which it is mounted. There is a less efficient thermal path between the plastic package and the LM74 die. If the
ambient air temperature is significantly different from the printed circuit board temperature, it will have a small
effect on the measured temperature.
In probe-type applications, the LM74 can be mounted inside a sealed-end metal tube, and can then be dipped
into a bath or screwed into a threaded hole in a tank. As with any IC, the LM74 and accompanying wiring and
circuits must be kept insulated and dry, to avoid leakage and corrosion. This is especially true if the circuit may
operate at cold temperatures where condensation can occur. Printed-circuit coatings and varnishes such as
Humiseal and epoxy paints or dips are often used to insure that moisture cannot corrode the LM74 or its
connections.
DSBGA Light Sensitivity
The LM74 in the DSBGA package should not be exposed to ultraviolet light. The DSBGA package does not
completely encapsulate the LM74 die in epoxy. Exposing the LM74 DSBGA package to bright sunlight will not
immediatly cause a change in the output reading. Our experiments show that directly exposing the circuit side
(bump side) of the die to high intensity (≥ 1mW/cm2) ultraviolet light, centered at a wavelength of 254nm, for
greater than 20 minutes will deprogram the EEPROM cells in the LM74. Since the EEPROM is used for storing
calibration coefficients, the LM74 will function but the temperature accuracy will no longer be as specified. Light
can penetrate through the side of the package as well, so exposure to ultra violet radiation is not recommended
even after mounting.
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13
LM74
SNIS107K – MAY 2000 – REVISED MARCH 2013
www.ti.com
Typical Applications
Figure 17. Temperature monitor using Intel 196 processor
Figure 18. LM74 digital input control using microcontroller's general purpose I/O.
14
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Product Folder Links: LM74
LM74
www.ti.com
SNIS107K – MAY 2000 – REVISED MARCH 2013
REVISION HISTORY
Changes from Revision J (March 2013) to Revision K
•
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 14
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15
PACKAGE OPTION ADDENDUM
www.ti.com
16-Jul-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
Samples
(4/5)
(6)
LM74CIM-3
NRND
SOIC
D
8
95
Non-RoHS
& Green
Call TI
Level-1-235C-UNLIM
-55 to 150
LM74
CIM3
LM74CIM-3/NOPB
ACTIVE
SOIC
D
8
95
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 150
LM74
CIM3
LM74CIM-5
NRND
SOIC
D
8
95
Non-RoHS
& Green
Call TI
Level-1-235C-UNLIM
-55 to 150
LM74
CIM5
LM74CIM-5/NOPB
ACTIVE
SOIC
D
8
95
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 150
LM74
CIM5
LM74CIMX-3
NRND
SOIC
D
8
2500
Non-RoHS
& Green
Call TI
Level-1-235C-UNLIM
-55 to 150
LM74
CIM3
LM74CIMX-3/NOPB
ACTIVE
SOIC
D
8
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 150
LM74
CIM3
Samples
LM74CIMX-5/NOPB
ACTIVE
SOIC
D
8
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 150
LM74
CIM5
Samples
LM74CITP-3/NOPB
ACTIVE
DSBGA
YTA
5
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 125
10
Samples
LM74CITPX-3/NOPB
ACTIVE
DSBGA
YTA
5
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 125
10
Samples
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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