LM95221CIMMNOPB - NATIONAL SEMICONDUCTOR

LM95071

LM95071 SPI/MICROWIRE 13-Bit Plus Sign Temperature Sensor

Literature Number: SNIS137B

LM95071

SPI/MICROWIRE 13-Bit Plus Sign Temperature Sensor

General Description

The LM95071 is a low-power, high-resolution digital tem-

perature sensor with an SPI and MICROWIRE compatible

interface, available in the 5-pin SOT23. The host can query

the LM95071 at any time to read temperature. Its low oper-

ating current is useful in systems where low power consump-

tion is critical.

The LM95071 has 13-bit plus sign temperature resolution

(0.03125˚C per LSB) while operating over a temperature

range of −40˚C to +150˚C.

The LM95071’s 2.4V to 5.5V supply voltage range, fast

conversion rate, low supply current, and simple SPI interface

make it ideal for a wide range of applications.

Applications

nSystem Thermal Management

nPortable Electronic Devices

nPersonal Computers

nDisk Drives

nOffice Electronics

nElectronic Test Equipment

Features

nSmall SOT23-5 package saves space

nShutdown mode conserves power between temperature

readings

nOperates over a full −40˚C to +150˚C range

nSPI and MICROWIRE Bus interface

Key Specifications

jSupply Voltage 2.4V to 5.5V

jSupply Current operating 280 µA (typ)

shutdown 6 µA (typ)

jTemperature

Accuracy 0˚C to 70˚C ±1˚C (max)

−40˚C to 150˚C ±2˚C (max)

jTemperature

Resolution

0.03125 ˚C

Simplified Block Diagram

20106501

TRI-STATE®is a registered trademark of National Semiconductor Corporation.

February 2005

LM95071 13-Bit Plus Sign SPI/MICROWIRE Temperature Sensor

Connection Diagram

SOT23-5

20106502

TOP VIEW

NS Package Number MF05A

Ordering Information

Order Number Top Mark NS Package

Number Supply Voltage Transport Media

LM95071CIMFX T18C MF05A 2.4V to 5.5V 3000 Units in Tape and Reel

Pin Descriptions

Number

Symbol Name Description

1CSChip Select input This pin receives an active-low signal from the controller to select the device.

2 GND Ground This is the power and signal ground return.

3 SI/O Serial Input/Output This serial, bi-directional, data bus pin transmits and receives signals to and

from the controller. Schmitt trigger input in the input mode.

4 SC Serial bus clock This serial clock signal comes from the controller. Schmitt trigger input.

Positive Supply Voltage Supply a DC voltage from 2.4V to 5.5V to this pin and bypass with a 0.1 µF

ceramic capacitor to ground.

Typical Application

20106503

FIGURE 1. COP Microcontroller Interface

LM95071

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Absolute Maximum Ratings (Note 1)

Supply Voltage −0.3V to 6.0V

Voltage at any Pin −0.3V to V

+ 0.3V

Input Current at any Pin (Note 2) 5 mA

Storage Temperature −65˚C to +150˚C

ESD Susceptibility (Note 4)

Human Body Model

Machine Model

2000V

200V

Soldering process must comply with National

Semiconductor’s Reflow Temperature Profile

specifications. Refer to www.national.com/packaging.

(Note 3)

Operating Ratings

Specified Temperature Range

(Note 5) T

MIN

to T

MAX

LM95071CIMF −40˚C to +150˚C

Supply Voltage Range (V

)

LM95071CIMF 2.4V to +5.5V

Temperature-to-Digital Converter Characteristics Unless otherwise noted, these specifica-

tions apply for V

= 3.3V . Boldface limits apply for T

MIN

to T

MAX

;all other limits T

= +25˚C, unless oth-

erwise noted.

Parameter Conditions Typical

(Note 7)

LM95071CIMF

Limits

(Note 8)

Units

(Limit)

Temperature Error

(Note 6)

= 3.0V to 3.6V; T

= 0˚C to +70˚C ±1.0 ˚C (max)

= 3.0V to 3.6V; T

= −40˚C to +150˚C ±2.0 ˚C (max)

Line Regulation V

= 3.6V to 5.5V; T

= 0˚C to +70˚C +0.3 ˚C/V

(max)

= 3.0V to 2.4V; T

= 0˚C to +70˚C -0.6

Resolution 14

0.03125

Bits

˚C

Temperature

Conversion Time

(Note 9) 130 228 ms (max)

Quiescent Current Operating, Serial Bus Inactive 280 520 µA (max)

Shutdown 6 28 µA (max)

Logic Electrical Characteristics

DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for V

= 2.4 to 5.5V (Note 6). Bold-

face limits apply for T

MIN

to T

MAX

;all other limits T

= +25˚C, unless otherwise noted.

Symbol Parameter Conditions Typical

(Note 7)

Limits

(Note 8)

Units

(Limit)

IN(1)

Logical “1” Input Voltage 0.7xV

V (min)

+ 0.3 V (max)

IN(0)

Logical “0” Input Voltage −0.3 V (min)

0.3xV

V (max)

Input Hysteresis Voltage V

= 3.0V to 3.6V 0.4 0.33 V (min)

IN(1)

Logical “1” Input Current V

0.005 3.0 µA (max)

IN(0)

Logical “0” Input Current V

= 0V −0.005 −3.0 µA (min)

All Digital Inputs 20 pF

High Level Output Voltage I

= −400 µA 2.25 V (min)

Low Level Output Voltage I

= +1.6 mA 0.4 V (max)

O_TRI-STATE

TRI-STATE ®Output Leakage

Current

= GND

−1

µA (min)

µA (max)

LM95071

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Logic Electrical Characteristics (Continued)

SERIAL BUS DIGITAL SWITCHING CHARACTERISTICS Unless otherwise noted, these specifications apply for V

= 2.4V

to 5.5V (Note 6); C

(load capacitance) on output lines = 100 pF unless otherwise specified. Boldface limits apply for T

MIN

to T

MAX

;all other limits T

= +25˚C, unless otherwise noted.

Symbol Parameter Conditions Typical

(Note 7)

Limits

(Note 8)

Units

(Limit)

SC (Clock) Period 0.16

µs (min)

(max)

CS Low to SC (Clock) High Set-Up Time 100 ns (min)

CS Low to Data Out (SO) Delay 70 ns (max)

SC (Clock) Low to Data Out (SO) Delay 70 ns (max)

CS High to Data Out (SO) TRI-STATE 200 ns (max)

SC (Clock) High to Data In (SI) Hold Time 50 ns (min)

Data In (SI) Set-Up Time to SC (Clock) High 30 ns (min)

SC (Clock) High to CS High Hold Time 50 ns (min)

20106504

FIGURE 2. Data Output Timing Diagram

20106505

FIGURE 3. TRI-STATE Data Output Timing Diagram

20106506

FIGURE 4. Data Input Timing Diagram

LM95071

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Logic Electrical Characteristics (Continued)

Notes

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 (VI) at any pin exceeds the power supplies (VI<GND or VI>VDD) the current at that pin should be limited to 5 mA.

Note 3: Reflow temperature profiles are different for lead-free and non-lead-free packages.

Note 4: Human body model, 100 pF discharged through a 1.5 kΩresistor. Machine model, 200 pF discharged directly into each pin.

Note 5: The life expectancy of the LM95071 will be reduced when operating at elevated temperatures. LM95071 θJA (thermal resistance, junction-to-ambient) when

attached to a printed circuit board with 2 oz. foil is summarized in the table below:

Device Number NS Package

Number

Thermal

Resistance (θ

)

LM95071CIMF MF05A 250˚C/W

Note 6: The LM95071 will operate properly over the VDD supply voltage range of 2.4V to 5.5V.

Note 7: Typicals are at TA= 25˚C and represent most likely parametric norm.

Note 8: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 9: This specification is provided only to indicate how often temperature data is updated. The LM95071 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.

Note 10: For best accuracy, minimize output loading. Higher sink currents can affect sensor accuracy with internal heating.

LM95071

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Electrical Characteristics

TRI-STATE Test Circuit

20106508

FIGURE 5. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)

20106507

FIGURE 6.

LM95071

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Typical Performance Characteristics

Static Supply Current vs. Temperature MaximumTemperature Error

20106525 20106526

Conversion Time vs Temperature Typical Output Noise at 30˚C

20106527

20106529

LM95071

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1.0 Functional Description

The LM95071 temperature sensor incorporates a tempera-

ture sensor and 13-bit-plus-sign ∆Σ ADC (Delta-Sigma

Analog-to-Digital Converter). Compatibility of the LM95071’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 Manufacturer/Device ID

product.

1.1 POWER UP AND POWER DOWN

The LM95071 always powers up in a known state and in the

continuous conversion mode. Immediately after power up,

the LM95071 will output an erroneous code until the first

temperature conversion has completed.

When the supply voltage is less than about 1.6V (typical),

the LM95071 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.

1.2 SERIAL BUS INTERFACE

The LM95071 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 communi-

cation is framed by falling and rising chip select (CS) signal.

The CS signal should be held high for at least one clock

cycle (160 ns minimum) between communications. The

transmit-only communication (register read) consists of 16

clock cycles. A complete transmit/receive communication will

consist of 32 serial clocks (see Figure 7). 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. CS can be taken high at any

time during the transmit phase. If CS is brought low in the

middle of a conversion the LM95071 will complete the con-

version 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 LM95071

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. All

zeros must be shifted in order to place the LM95071 into

continuous conversion mode. Only the following codes

should be transmitted to the LM95071:

•00 hex for continuous conversion

•FF hex for shutdown

Another code may place the part into a test mode. Test

modes are used by National Semiconductor to thoroughly

test the function of the LM95071 during production testing.

Only eight bits have been defined above since only the last

eight transmitted are detected by the LM95071, before CS is

taken HIGH.

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 228 ms (max) will have to pass for a conversion to

complete before the LM95071 actually transmits tempera-

ture data.

1.3 TEMPERATURE DATA FORMAT

Temperature data is represented by a 14-bit, two’s comple-

ment word with an LSB (Least Significant Bit) equal to

0.03125˚C:

Temperature Digital Output

Binary Hex

+150˚C 0100 1011 0000 0011 4B03

+125˚C 0011 1110 1000 0011 3E83

+25˚C 0000 1100 1000 0011 0C83

+0.03125˚C 0000 0000 0000 0111 0007

0˚C 0000 0000 0000 0011 0003

−0.03125˚C 1111 1111 1111 1111 FFFF

−25˚C 1111 0011 1000 0011 F383

−40˚C 1110 1100 0000 0011 EC03

The first data byte is the most significant byte with most

significant bit first, permitting only as much data as neces-

sary 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 im-

mediately take action to remedy the excessive tempera-

tures.

1.4 SHUTDOWN MODE/MANUFACTURER ID

The master controller may enable the shutdown mode for

the purpose of reducing power consumption or for reading

the Manufacturer/Device ID information. The shutdown

mode is enabled by writing XX FF hex to the LM95071 as

shown in Figure 7c. The serial bus is still active when the

LM95071 is in shutdown. When in shutdown mode the

LM95071 always will output 1000 0000 0000 1111. This is

the Manufacturer/Device ID information. The first 5-bits of

the field (1000 0XXX) are reserved for the manufacturer ID.

LM95071

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1.0 Functional Description (Continued)

1.5 INTERNAL REGISTER STRUCTURE

The LM95071 has three registers: the temperature register,

the configuration register and the Manufacturer/Device iden-

tification register. The temperature and Manufacturer/Device

identification registers are read only. The configuration reg-

ister is write only.

1.5.1 Configuration Register

(Selects shutdown or continuous conversion modes):

(Write Only):

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

XXXXXXXX Shutdown

D0–D15 set to XX FF hex enables shutdown mode.

D0–D15 set to XX 00 hex sets continuous-conversion mode.

Note: setting D0-D15 to any other values may place the LM95071 into a manufacturer’s test mode, upon which the LM95071 will

stop responding as described. These test modes are to be used for National Semiconductor production testing only. See Section

1.2, Serial Bus Interface, for a complete discussion.

1.5.2 Temperature Register

(Read Only):

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

MSB Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit1 LSB 1 1

D0–D1: Logic 1 will be output on SI/0.

D2–D15: Temperature Data. One LSB = 0.03125˚C. Two’s complement format.

1.5.3 Manufacturer/Device ID Register

(Read Only):

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

1000000000001111

D0–D1: Logic 1 will be output on SI/0.

D2–D15: Manufacturer/Device ID Data. This register is accessed whenever the LM95071 is in shutdown mode.

LM95071

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2.0 Serial Bus Timing Diagrams

20106514

a) Reading Continuous Conversion - Single Eight-Bit Frame

20106515

b) Reading Continuous Conversion - Two Eight-Bit Frames

20106518

c) Writing Shutdown Mode

20106522

d) Writing Conversion Mode

FIGURE 7. Timing Diagrams

LM95071

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3.0 Application Hints

3.1 THERMAL PATH CONSIDERATIONS

To get the expected results when measuring temperature

with an integrated circuit temperature sensor like the

LM95071, it is important to understand that the sensor mea-

sures its own die temperature. For the LM95071, the best

thermal path between the die and the outside world is

through the LM95071’s pins. In the SOT23 package, all the

pins on the LM95071 will have an equal effect on the die

temperature. Because the pins represent a good thermal

path to the LM95071 die, the LM95071 will provide an accu-

rate measurement of the temperature of the printed circuit

board on which it is mounted. There is a less efficient ther-

mal path between the plastic package and the LM95071 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.

3.2 OUTPUT CONSIDERATIONS: TIGHT ACCURACY,

FINE RESOLUTION AND LOW NOISE

The LM95071 is well suited for applications that require tight

temperature measurement accuracy. In many applications,

from process control to HVAC, the low temperature error can

mean better system performance and, by eliminating a sys-

tem calibration step, lower production cost.

With it’s fine digital resolution the LM95071 senses and

reports very small changes in its temperature, making it ideal

for applications where temperature sensitivity is important.

For example, the LM95071 enables the system to quickly

identify the direction of temperature change, allowing the

processor to take compensating action before the system

reaches a critical temperature.

The LM95071 has very low output noise (see the Output

Noise plot in the Typical Performance section), which makes

it ideal for applications where stable thermal compensation

is a priority. For example, in a temperature-compensated

oscillator application, the very small deviation in successive

temperature readings translates to a stable frequency output

from the oscillator.

4.0 Typical Applications

20106520

FIGURE 8. Temperature monitor using Intel 196 processor

20106519

FIGURE 9. LM95071 digital input control using microcontroller’s general purpose I/O.

LM95071

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Physical Dimensions inches (millimeters) unless otherwise noted

LM95071Top View

SOT23-5 Package

NS Package Number MF05A

LM95071

www.national.com 12

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves

the right at any time without notice to change said circuitry and specifications.

For the most current product information visit us at www.national.com.

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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS

WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR

CORPORATION. As used herein:

1. Life support devices or systems are devices or systems

which, (a) are intended for surgical implant into the body, or

(b) support or sustain life, and whose failure to perform when

properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result

in a significant injury to the user.

2. A critical component is any component of a life support

device or system whose failure to perform can be reasonably

expected to cause the failure of the life support device or

system, or to affect its safety or effectiveness.

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National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship

Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned

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LM95071 13-Bit Plus Sign SPI/MICROWIRE Temperature Sensor

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