LM70
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SNIS112G – JUNE 2000 – REVISED MARCH 2013
LM70 SPI/MICROWIRE 10-Bit plus Sign Digital Temperature Sensor
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FEATURES
1
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2
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0.25°C Temperature Resolution.
Shutdown Mode Conserves Power Between
Temperature Reading
SPI and MICROWIRE Bus Interface
VSSOP-8 and WSON-8 Packages Save Space
UL Recognized Component
APPLICATIONS
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System Thermal Management
Personal Computers
Disk Drives
Office Electronics
Electronic Test Equipment
KEY SPECIFICATIONS
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DESCRIPTION
The LM70 is a temperature sensor, Delta-Sigma
analog-to-digital converter with an SPI and
MICROWIRE compatible interface available in WSON
and VSSOP 8-pin packages. The host can query the
LM70 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.
The LM70 has 10-bit plus sign temperature resolution
(0.25°C per LSB) while operating over a temperature
range of −55°C to +150°C.
The LM70's 2.65V 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.
Supply Voltage 2.65V to 5.5V
Supply Current
– Operating
– 260 μA (typ)
– 490 μA (max)
– Shutdown
– 12 μA (typ)
Temperature Accuracy
– −40°C to 85°C, ±2°C(max)
– −10°C to 65°C, +1.5/−2°C(max)
– −55°C to 125°C, +3/−2°C(max)
– −55°C to 150°C, +3.5/−2°C(max)
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
LM70
SNIS112G – JUNE 2000 – REVISED MARCH 2013
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Simplified Block Diagram
Connection Diagram
Top View
Top View
Figure 1. VSSOP-8 Package
See Package Number DGK0008A
Figure 2. WSON-8 Package
See Package Number NGK0008A
PIN DESCRIPTIONS
VSSOP-8
Pin No.
WSON-8
Pin No.
SI/O
1
1
Input/Output - Serial bus bi-directional data line.
Schmitt trigger input.
From and to Controller
SC
2
3
Clock - Serial bus clock Schmitt trigger input line.
From Controller
GND
4
7
Power Supply Ground
Ground
V+
5
5
Positive Supply Voltage Input
DC Voltage from 2.65V to 5.5V. Bypass with a
0.1 μF ceramic capacitor.
CS
7
8
Chip Select input.
From Controller
NC
3, 6, 8
2, 4, 6
No Connect
These pins are not connected to the LM70 die
in any way.
Pin Name
2
Description
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Typical Connection
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Typical Application
Figure 3. 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.
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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
Soldering Information, Lead Temperature
VSSOP-8 and WSON-8 Packages (3)
Vapor Phase (60 seconds)
Infrared (15 seconds)
215°C
220°C
ESD Susceptibility (4)
Human Body Model
3000V
Machine Model
(1)
(2)
(3)
(4)
300V
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.
See the section titled “Surface Mount” found in a current Linear Data Book for other methods of soldering surface mount devices.
Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin.
Operating Ratings
Specified Temperature Range
See
TMIN to TMAX
(1)
−55°C to +150°C
Supply Voltage Range (+VS)
(1)
+2.65V to +5.5V
The life expectancy of the LM70 will be reduced when operating at elevated temperatures. LM70 θJA (thermal resistance, junction-toambient) when attached to a printed circuit board with 2 oz. foil is summarized in the table below:Device Number LM70CILD Thermal
Resistance (θJA), 51.3°C/W, Device Number LM70CIMM Thermal Resistance (θJA), 200°C/W
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for V+ = 2.65V to 3.6V for the LM70-3 and V+ = 4.5V to 5.5V for the LM705 (1). Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ=+25°C, unless otherwise noted.
LM70-5
Limits (3)
LM70-3
Limits (3)
Units
(Limit)
TA = −10°C to +65°C
+1.5/−2.0
+1.5/−2.0
°C (max)
TA = −40°C to +85°C
±2.0
±2.0
°C (max)
TA = −55°C to +125°C
+3.0/−2.0
+3.0/−2.0
°C (max)
+3.5/−2.0
+3.5/−2.0
°C (max)
Parameter
Temperature Error (1)
Test Conditions
Typical (2)
TA = −55°C to +150°C
Resolution
11
0.25
Bits
°C
Temperature Conversion Time
See (4)
140
210
210
ms (max)
Quiescent Current
Serial Bus Inactive
260
490
490
μA (max)
Serial Bus Active
260
μA
Shutdown Mode
12
μA
(1)
(2)
(3)
(4)
4
Both part numbers of the LM70 will operate properly over the V+ supply voltage range of 2.65V to 5.5V. The temperature error for
temperature ranges of −10°C to +65°C, −40°C to +85°C, −55°C to +125°C and −55°C to +150°C include error induced by power supply
variation of ±5% from the nominal value. Temperature error will increase by ±0.3°C for a power supply voltage (V+) variation of ±10%
from the nominal value.
Typicals are at TA = 25°C and represent most likely parametric norm.
Limits are guaranteed to AOQL (Average Outgoing Quality Level).
This specification is provided only to indicate how often temperature data is updated. The LM70 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 LM70-3 and V+ = 4.5V to 5.5V for the LM705. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ=+25°C, unless otherwise noted.
Parameter
VIN(1)
VIN(0)
Test Conditions
Typical (1)
Logical “1” Input Voltage
Logical “0” Input Voltage
Input Hysteresis Voltage
Units
(Limit)
Limits (2)
V+ × 0.7
V (min)
V+ + 0.3
V (max)
−0.3
V (min)
V+ × 0.3
V (max)
V (min)
V+ = 2.65V to 3.6V
0.8
0.27
V+ = 4.5V to 5.5V
0.8
0.35
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)
20
pF
Typicals are at TA = 25°C and represent most likely parametric norm.
Limits are guaranteed to AOQL (Average Outgoing Quality Level).
Logic Electrical Characteristics Serial Bus Digital Switching Characteristics
Unless otherwise noted, these specifications apply for V+ = 2.65V to 3.6V for the LM70-3 and V+ = 4.5V to 5.5V for the LM705, 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.
Parameter
Test Conditions
Typical (1)
Limits (2)
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
70
ns (max)
t5
CS High to Data Out (SO) TRI-STATE
200
ns (min)
t6
SC (Clock) High to Data In (SI) Hold Time
60
ns (min)
t7
Data In (SI) Set-Up Time to SC (Clock) High
30
ns (min)
(1)
(2)
Typicals are at TA = 25°C and represent most likely parametric norm.
Limits are guaranteed to AOQL (Average Outgoing Quality Level).
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Timing Diagrams
Figure 4. Data Output Timing Diagram
Figure 5. TRI-STATE Data Output Timing Diagram
Figure 6. Data Input Timing Diagram
6
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Figure 7. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)
Figure 8. TRI-STATE Test Circuit
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Typical Performance Characteristics
Average Power-On Reset Voltage vs Temperature
Static Supply Current vs Temperature
Figure 9.
Figure 10.
Temperature Error
Figure 11.
8
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SNIS112G – JUNE 2000 – REVISED MARCH 2013
FUNCTIONAL DESCRIPTION
The LM70 temperature sensor incorporates a band-gap type temperature sensor and 10-bit plus sign ΔΣ ADC
(Delta-Sigma Analog-to-Digital Converter). Compatibility of the LM70'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 ID register identifies the LM70 as a
TI product.
POWER UP AND POWER DOWN
The LM70 always powers up in a known state. The power up default condition is continuous conversion mode.
Immediatly after power up the LM70 will output an erroneous code until the first temperature conversion has
completed.
When the supply voltage is less than about 1.6V (typical), the LM70 is considered powered down. As the supply
voltage rises above the nominal 1.6V power up threshold, the internal registers are reset to the power up default
state described above.
SERIAL BUS INTERFACE
The LM70 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 TRISTATE. 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, ten temperature bits
and 3 high bits) 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 LM70 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
LM70 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
LM70 out of shutdown. The following codes only should be transmitted to the LM70:
• 00 hex (normal operation)
• 01 hex (normal operation)
• 03 hex (normal operation)
• 07 hex (normal operation)
• 0F hex (normal operation)
• 1F hex (normal operation)
• 3F hex(normal operation)
• 7F hex(normal operation)
• FF hex (Shutdown, transmit manufacturer's ID)
any others may place the part into a Test Mode. Test Modes are used by TI to thoroughly test the function of the
LM70 during production testing. Only eight bits have been defined above since only the last eight transmitted,
before CS is taken HIGH, are detected by the LM70
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.
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Note that 210 ms will have to pass for a conversion to complete before the LM70 actually transmits temperature
data.
TEMPERATURE DATA FORMAT
Temperature data is represented by a 11-bit, two's complement word with an LSB (Least Significant Bit) equal to
0.25°C:
Digital Output
Temperature
Binary
Hex
+150°C
0100 1011 0001 1111
4B 1Fh
+125°C
0011 1110 1001 1111
3E 9Fh
+25°C
0000 1100 1001 1111
0B 9Fh
+0.25°C
0000 0000 0011 1111
00 3Fh
0°C
0000 0000 0001 1111
00 1Fh
−0.25°C
1111 1111 1111 1111
FF FFh
−25°C
1111 0011 1001 1111
F3 9Fh
−55°C
1110 0100 1001 1111
E4 9Fh
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 LM70 as shown in Figure 14c. and discussed in Section 1.2.
The serial bus is still active when the LM70 is in shutdown. Current draw drops to less than 10 µA between serial
communications. When in shutdown mode the LM70 always will output 1000 0001 0000 00XX. This is the
manufacturer's ID/Device ID information. The first 5-bits of the field (1000 0XXX) are reserved for manufacturer's
ID.
INTERNAL REGISTER STRUCTURE
The LM70 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):
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 XX 00 hex enables continuous conversion mode.
Note: setting D0-D15 to any other values may place the LM70 into a manufacturer's test mode, upon which the
LM70 will stop responding as described. These test modes are to be used for production testing only. See
Section 1.2 Serial Bus Interface for a complete discussion.
10
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TEMPERATURE REGISTER
Table 2. (Read Only):
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
MSB
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
LSB
1
1
1
X
X
D0–D1: Undefined. TRI-STATE will be output on SI/0.
D2–D4: Always set high.
D5–D15: Temperature Data. One LSB = 0.25°C. Two's complement format.
MANUFACTURER'S/DEVICE ID REGISTER
Table 3. (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
1
0
0
0
0
0
0
X
X
D0–D1: Undefined. TRI-STATE will be output on SI/0.
D2-D4: Always set LOW.
D5–D15: Manufacturer's ID Data. This register is accessed whenever the LM70 is in shutdown mode.
Serial Bus Timing Diagrams
Figure 12. a) Reading Continuous Conversion - Single Eight-Bit Frame
Figure 13. b) Reading Continuous Conversion - Two Eight-Bit Frames
Figure 14. c) Writing Shutdown Control
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Application Hints
To get the expected results when measuring temperature with an integrated circuit temperature sensor like the
LM70, it is important to understand that the sensor measures its own die temperature. For the LM70, the best
thermal path between the die and the outside world is through the LM70's pins. In the VSSOP-8 package the
ground pin is connected to the back side of the LM70 die and thus has the most effect on the die temperature.
Although the other pins will also have some effect on the LM70die temperature and therefore should not be
discounted. The LM70 will provide an accurate measurement of the temperature of the printed circuit board on
which it is mounted, because the pins represent a good thermal path to the die. A less efficient thermal path
exists between the plastic package and the LM70 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 LM70 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 LM70 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 LM70 or its
connections.
Typical Applications
Figure 15. Temperature Monitor Using Intel 196 Processor
12
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Figure 16. LM70 Digital Input Control Using Micro-Controller's General Purpose I/O
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REVISION HISTORY
Changes from Revision F (March 2013) to Revision G
•
14
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 13
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PACKAGE OPTION ADDENDUM
www.ti.com
29-Mar-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)
(4/5)
(6)
LM70CILD-3/NOPB
ACTIVE
WSON
NGK
8
1000
RoHS & Green
SN
Level-3-260C-168 HR
-55 to 150
T33
LM70CILD-5/NOPB
ACTIVE
WSON
NGK
8
1000
RoHS & Green
SN
Level-3-260C-168 HR
-55 to 150
T35
LM70CILDX-3/NOPB
ACTIVE
WSON
NGK
8
4500
RoHS & Green
SN
Level-3-260C-168 HR
-55 to 150
T33
LM70CIMM-3
NRND
VSSOP
DGK
8
1000
Non-RoHS
& Green
Call TI
Level-1-260C-UNLIM
-55 to 150
T04C
LM70CIMM-3/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 150
T04C
LM70CIMM-5
NRND
VSSOP
DGK
8
1000
Non-RoHS
& Green
Call TI
Level-1-260C-UNLIM
-55 to 150
T03C
LM70CIMM-5/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 150
T03C
LM70CIMMX-3/NOPB
ACTIVE
VSSOP
DGK
8
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 150
T04C
LM70CIMMX-5/NOPB
ACTIVE
VSSOP
DGK
8
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-55 to 150
T03C
(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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