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LM32

Dual Thermal Diode Temperature Sensor with

SensorPath

™

Bus

General Description

The LM32 is a digital temperature sensor that measures 3

temperature zones and has a single-wire interface compat-

ible with National Semiconductor’s SensorPath bus. Sensor-

Path data is pulse width encoded, thereby allowing the LM32

to be easily connected to many general purpose micro-

controllers. Several National Semiconductor Super I/O prod-

ucts include a fully integrated SensorPath master, that when

connected to an LM32 can realize a hardware monitor func-

tion that includes limit checking for measured values, au-

tonomous fan speed control and many other functions.

The LM32 measures the temperature of its own die as well

as two external devices such as a processor thermal diode

or a diode connected transistor. The LM32 can resolve tem-

peratures up to 255˚C and down to -256˚C. The operating

temperature range of the LM32 is 0˚C to +125˚C. The ad-

dress programming pin allows two LM32s to be placed on

one SensorPath bus.

Features

n SensorPath Interface

— 2 hardware programmable addresses

n 2 remote diode temperature sensor zones

n Internal local temperature zone

n 0.5 ˚C resolution

n Measures temperatures up to 140 ˚C

n 14-lead TSSOP package

Key Specifications

n Temperature Sensor Accuracy

3 ˚C (max)

n Temperature Range:

— LM32 junction 0 ˚C to +85 ˚C

— Remote Temp Accuracy 0 ˚C to +100 ˚C

n Power Supply Voltage +3.0 V to +3.6 V

n Average Power Supply Current 0.5 mA (typ)

n Conversion Time (all Channels) 22.5ms to 1456ms

Applications

n Microprocessor based equipment

(Motherboards, Video Cards, Base-stations, Routers,

ATMs, Point of Sale, …)

n Power Supplies

Typical Application

20071101

SensorPath

™

is a trademark of National Semiconductor Corporation

May 2004

LM32 Dual Thermal Diode Temperature Sensor with SensorPath

™

Bus

Summary of content (24 pages)

PAGE 1
LM32 Dual Thermal Diode Temperature Sensor with SensorPath™ Bus General Description The LM32 is a digital temperature sensor that measures 3 temperature zones and has a single-wire interface compatible with National Semiconductor’s SensorPath bus. SensorPath data is pulse width encoded, thereby allowing the LM32 to be easily connected to many general purpose microcontrollers.
PAGE 2
LM32 Connection Diagram Order Number TSSOP-14 Package Marking NS Package Number Transport Media LM32CIMT LM32 CIMT MTC14C 94 units per rail LM32CIMTX LM32 CIMT MTC14C 2500 units in tape and reel 20071102 Top View National Package Number MTC14C Pin Description Pin Number Pin Name Description Typical Connection 1, 6, 7,12, 13, 14 NC No Connect May be tied to V+, GND or left floating 2 GND 3 V+/+3.3V_SBY Ground System ground Positive power supply pin Connected system 3.
PAGE 3
LM32 Block Diagram 20071103 3 www.national.
PAGE 4
LM32 Absolute Maximum Ratings Storage Temperature (Notes 2, 1) Soldering process must comply with National’s reflow temperature profile specifications. Refer to www.national.com/packaging/. (Note 6) Supply Voltage (V+) −0.5 V to 6.0 V Voltage at Any Digital Input or Output Pin Voltage on D1+ and D2+ −0.5 V to 6.0 V −65˚C to +150˚C Operating Ratings −0.5 V to (V+ + 0.
PAGE 5
Symbol Parameter Conditions Typical (Note 7) SWD Logical High Input Voltage VIH VIL SWD Logical Low Input Voltage VIH ADD Logical High Input Voltage VIL ADD Logical Low Input Voltage VHYST IL Input Hysteresis SWD and ADD Input Current GND ≤ VIN ≤ V+ ± 0.005 ± 0.005 Digital Input Capacitance CIN SWD DIGITAL OUTPUT CHARACTERISTICS IOH Conditions I I Typical (Note 7) V (min) V (max) 0.8 V (max) -0.
PAGE 6
LM32 AC Electrical Characteristics (Continued) The following specification apply for V+ = +3.0 VDC to +3.6 VDC, unless otherwise specified. Boldface limits apply for TA = TJ = TMIN=0˚C to TMAX=85˚C; all other limits TA = TJ = 25˚C. The SensorPath Characteristics conform to the SensorPath specification revision 0.98. Please refer to that speciation for further details.
PAGE 7
LM32 Timing Diagrams 20071104 FIGURE 1. Timing for Data Bits 0, 1 and Start Bit. See Section 1.2 "SensorPath BIT SIGNALING" for further details. 7 www.national.
PAGE 8
LM32 Timing Diagrams (Continued) 20071105 FIGURE 2. Timing for Attention Request and Reset. See Section 1.2 "SensorPath BIT SIGNALING" for further details. www.national.
PAGE 9
LM32 Typical Performance Characteristics Remote Diode Temperature Reading Sensitivity to Diode Filter Capacitance Thermal Diode Capacitor or PCB Leakage Current Effect on Remote Diode Temperature Reading 20071121 20071122 1.0 Functional Description The LM32 measures 3 temperature zones. The LM32 uses a ∆Vbe temperature sensing method. A differential voltage, representing temperature, is digitized using a Sigma-Delta analog to digital converter.
PAGE 10
LM32 1.0 Functional Description measuring the time SWD is active (low). If an Attention Request or Reset condition is detected, the current "bit signal" is not treated as a Start Bit. The master may attempt to send the Start Bit at a later time. (Continued) Signal labels that begin with the label Slv_ depict the drive by the LM32. All other signals show what would be seen when probing SWD for a particular function (e.g. "Master Wr 0" is the Master transmitting a Data Bit with the value of 0). 1.2.
PAGE 11
LM32 1.0 Functional Description (Continued) 20071108 FIGURE 4. Bus Reset Transaction • Acknowledge (ACK) During a read transaction the ACK bit is sent by the master indicating that the EP bit was received and was found to be correct, when compared to the data preceding it, and that no conflict was detected on the bus (excluding Attention Request - see Section 1.3.5 "Attention Request Transaction"). A read transfer is considered "complete" only when the ACK bit is received.
PAGE 12
LM32 1.0 Functional Description Request - see Section 1.3.5 "Attention Request Transaction"). A write transfer is considered "completed" only when the ACK bit is generated. A transaction that was not positively acknowledged is not considered complete by the LM32 (i.e.
PAGE 13
their Device Status register and must handle any pending event in them before it may assume that there are no more events to handle. (Continued) All devices (master or slave) must monitor the bus for an Attention Request signal. The following notes clarify the intended system operation that uses the Attention Request Indication. • Masters are expected to use the attention request as a trigger to read results from the LM32. This is done in a sequence that covers all LM32s.
PAGE 14
LM32 2.0 Register Set 2.
PAGE 15
LM32 2.0 Register Set (Continued) Reg Add Register Name R/ W 000 000 Device Number R P O R Val 7h or 1h Bit 7 Bit 6 0 0 Bit 5 Bit 4 Bit 3 0 0 Bit 2 Bit 1 Bit 0 LSb AS2 AS1 AS0 Reserved 0 The value of [AS2:AS0] is determined by the setting of the ADD input pin: TABLE 1. Device Number Assignment ADD [AS2:AS0] 0 001 1 111 The value of [AS2:AS0] will directly change and follow the value determined by ADD.
PAGE 16
LM32 2.0 Register Set (Continued) 2.5 DEVICE ID (Addr: 000 010; 02h) Reg Add Register Name 000 010 Device ID R/ W P O R Val R 23h Bit Bit 15 14 MSb Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 0 0 0 0 0 0 0 RevID 0 0 0 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 LSb 0 0 1 1 DeviceID 1 0 The device ID is defined by the manufacturer of the device and is unique for each device produced by a manufacturer.
PAGE 17
LM32 2.0 Register Set (Continued) 2.8 DEVICE CONTROL (Addr: 000 101; 05h) This register responds to a broadcast write command (Device Number 000). Write using broadcast address is ignored by bits 15-2. This register is set to the reset value by a Device Reset.
PAGE 18
LM32 2.0 Register Set (Continued) register clears also the Error Function 1 flag (ERF1). The Readout register contains the temperature data, and the sensor number. Since the LM32 only supports three temperature zones the sensor number field will be zero to two. Other fields in the Readout register as defined by the SensorPath specification are not supported. Readout Resolution The resolution of the readout is defined in the Temperature Capabilities register.
PAGE 19
LM32 2.0 Register Set (Continued) 2.9.3 Temperature Data Readout (Addr: 001 001; 09h) Reg Add Register Name R/ W P O R Val Local Temperature Data Readout Bit Bit 15 14 MSb Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Reserved 0 001 001 Processor/ Remote Temperature Data Readout R MSb 128 64˚C 32˚C 16˚C 8˚C Sign ˚C 4˚C 2˚C 1˚C 0.5 ˚C Bit 1 Bit 0 LSb Reserved 0 0 0 SNUM Reserved Res EF 0 0 0 Bit Type 0 RO Reserved.
PAGE 20
LM32 2.0 Register Set (Continued) Temperature Data Format (Continued) Temperature Binary Hex - 40 ˚C 11 1011 0000 3B0h -255.5 ˚C 10 0000 0001 201h -256 ˚C 10 0000 0000 200h 2.9.4 Temperature Control (Addr: 001 010; 0Ah) This register is set to the reset value by a Device Reset.
PAGE 21
LM32 2.0 Register Set (Continued) Conversion Rate Control (Continued) LowPwr [CR1:CR0] 0 01 Typical Conversion Rate (ms) 91 1 01 364 0 10 182 (default) 1 10 728 0 11 364 1 11 1456 *Fastest: 2x7.5ms(remote) + 7.5msec (local) = 22.5 ms total The sensor conversion rate is controlled by this register as well as the Low Power Bit of Device Control Register. This register is not defined by the SensorPath specification.
PAGE 22
LM32 3.0 Application Hints • • • • (Continued) Pentium 4 on 0.13 micron process, 2-3.06GHz 1.0011 1.0021 1.0030 3.64 Ω Pentium 4 on 90 nm process −19 q = 1.6x10 Coulombs (the electron charge), T = Absolute Temperature in Kelvin k = 1.38x10−23joules/K (Boltzmann’s constant), Pentium M Processor (Centrino) 1.00151 1.00220 1.00289 3.
PAGE 23
9. Leakage current between D+ and GND should be kept to a minimum. Seventeen nano-amperes of leakage can cause as much as 0.2˚C of error in the diode temperature reading (see curve in Section Typical Performance Characteristics). Keeping the printed circuit board as clean as possible will minimize leakage current. The SensorPath Bus is less sensitive to noise than its predecessor the SMBus due to the inherent filtering present in the pulse-width encoding of the data.
PAGE 24
LM32 Dual Thermal Diode Temperature Sensor with SensorPath™ Bus Physical Dimensions inches (millimeters) unless otherwise noted 14-Lead Molded Thin Shrink Small Outline Package (TSSOP, JEDEC Registration Number MO-153 Variation AB Ref Note 6 dated 7/93, Order Number LM32CIMT, or LM32CIMTX, NS Package Number MTC14C LIFE SUPPORT POLICY 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