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LM95221

Dual Remote Diode Digital Temperature Sensor with

SMBus Interface

General Description

The LM95221 is a dual remote diode temperature sensor in

an 8-lead MSOP package. The 2-wire serial interface of the

LM95221 is compatible with SMBus 2.0. The LM95221 can

sense three temperature zones, it can measure the tempera-

ture of its own die as well as two diode connected transis-

tors. The diode connected transistors can be a thermal diode

as found in Pentium and AMD processors or can simply be a

diode connected MMBT3904 transistor. The LM95221 reso-

lution format for remote temperature readings can be pro-

grammed to be 10-bits plus sign or 11-bits unsigned. In the

unsigned mode the LM95221 remote diode readings can

resolve temperatures above 127˚C. Local temperature read-

ings have a resolution of 9-bits plus sign.

The temperature of any ASIC can be accurately determined

using the LM95221 as long as a dedicated diode (semicon-

ductor junction) is available on the target die. The LM95221

remote sensor accuracy of

1˚C is factory trimmed for a

series resistance of 2.7 ohms and 1.008 non-ideality factor.

Features

n Accurately senses die temperature of remote ICs or

diode junctions

n Remote diode fault detection

n On-board local temperature sensing

n Remote temperature readings:

— 0.125 ˚C LSb

— 10-bits plus sign or 11-bits programmable resolution

— 11-bits resolves temperatures above 127 ˚C

n Local temperature readings:

— 0.25 ˚C

— 9-bits plus sign

n Status register support

n Programmable conversion rate allows user optimization

of power consumption

n Shutdown mode one-shot conversion control

n SMBus 2.0 compatible interface, supports TIMEOUT

n 8-pin MSOP package

Key Specifications

Local Temperature Accuracy

=0˚C to 85˚C

3.0 ˚C (max)

Remote Diode Temperature Accuracy

=30˚C to 50˚C, T

=45˚C to 85˚C

1.0 ˚C (max)

=0˚C to 85˚C, T

=25˚C to 140˚C

3.0 ˚C (max)

Supply Voltage 3.0 V to 3.6 V

Supply Current 2 mA (typ)

Applications

n Processor/Computer System Thermal Management

(e.g. Laptop, Desktop, Workstations, Server)

n Electronic Test Equipment

n Office Electronics

Simplified Block Diagram

20094301

Pentium

™

is a trademark of Intel Corporation.

May 2004

LM95221 Dual Remote Diode Digital Temperature Sensor with SMBus Interface

Summary of content (16 pages)

PAGE 1
LM95221 Dual Remote Diode Digital Temperature Sensor with SMBus Interface General Description The LM95221 is a dual remote diode temperature sensor in an 8-lead MSOP package. The 2-wire serial interface of the LM95221 is compatible with SMBus 2.0. The LM95221 can sense three temperature zones, it can measure the temperature of its own die as well as two diode connected transistors.
PAGE 2
LM95221 Connection Diagram MSOP-8 20094302 TOP VIEW Ordering Information Package Marking NS Package Number Transport Media SMBus Device Address LM95221CIMM LM95221CIMM MUA08A (MSOP-8) 1000 Units on Tape and Reel 010 1011 LM95221CIMMX LM95221CIMM MUA08A (MSOP-8) 3500 Units on Tape and Reel 010 1011 Part Number Pin Descriptions Label Pin # D1+ 1 Diode Current Source To Diode Anode.
PAGE 3
LM95221 Pin Descriptions (Continued) Label Pin # Function SMBDAT 7 SMBus Bi-Directional Data Line, Open-Drain Output From and to Controller; may require an external pull-up resistor Typical Connection SMBCLK 8 SMBus Clock Input From Controller; may require an external pull-up resistor Typical Application 20094303 3 www.national.
PAGE 4
LM95221 Absolute Maximum Ratings (Note 1) Supply Voltage Infrared (15 seconds) ESD Susceptibility (Note 4) −0.3 V to 6.0 V Voltage at SMBDAT, SMBCLK Voltage at Other Pins Human Body Model −0.5V to 6.0V 2000 V Machine Model −0.3 V to (VDD + 0.
PAGE 5
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for VDD=+3.0 to 3.6 Vdc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA= TJ=+25˚C, unless otherwise noted. Symbol Parameter Conditions Typical Limits Units (Note 6) (Note 7) (Limit) 2.1 V (min) 0.
PAGE 6
LM95221 SMBus Communication 20094309 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. Parasitic components and or ESD protection circuitry are shown in the figure below for the LM95221’s pins.
PAGE 7
Thermal Diode Capacitor or PCB Leakage Current Effect Remote Diode Temperature Reading Remote Temperature Reading Sensitivity to Thermal Diode Filter Capacitance 20094305 20094307 Conversion Rate Effect on Average Power Supply Current 20094306 to sense temperatures above 127˚C. Local temperature resolution is not programmable and is always 9-bits plus sign and has a 0.25˚C LSb.
PAGE 8
LM95221 1.0 Functional Description 7. specifications, the LM95221 has a 7-bit slave address. All bits A6 through A0 are internally programmed and can not be changed by software or hardware. The LM95221 has the following SMBus slave address: (Continued) Status Register: busy, diode fault 8. Configuration Register: resolution control, conversion rate control, standby control 9. 1-shot Register 10. Manufacturer ID 11. Revision ID Version A6 A5 A4 A3 A2 A1 A0 LM95221 0 1 0 1 0 1 1 1.
PAGE 9
Temperature set to “00”, the location for the Read Local Temperature Register. The Command Register latches the last location it was set to. Each data register in the LM95221 falls into one of four types of user accessibility: 1. Read only 2. Write only (Continued) Digital Output Binary Hex −0.25˚C 1111 1111 1100 0000 FFE0h −1˚C 1111 1111 0000 0000 FF00h −25˚C 1110 0111 0000 0000 E700h −55˚C 1100 1001 0000 0000 C900h 3. Write/Read same address 4.
PAGE 10
LM95221 1.0 Functional Description (Continued) 20094310 (a) Serial Bus Write to the internal Command Register followed by a the Data Byte 20094311 (b) Serial Bus Write to the Internal Command Register 20094312 (c) Serial Bus Read from a Register with the Internal Command Register preset to desired value. 20094314 (d) Serial Bus Write followed by a Repeat Start and Immediate Read FIGURE 3. SMBus Timing Diagrams www.national.
PAGE 11
2. (Continued) 1.8 SERIAL INTERFACE RESET In the event that the SMBus Master is RESET while the LM95221 is transmitting on the SMBDAT line, the LM95221 must be returned to a known state in the communication protocol. This may be done in one of two ways: 1. When SMBDAT is HIGH, have the master initiate an SMBus start. The LM95221 will respond properly to an SMBus start condition at any point during the communication. After the start the LM95221 will expect an SMBus Address address byte. 1.
PAGE 12
LM95221 2.0 LM95221 Registers (Continued) 2.1 STATUS REGISTER (Read Only Address 02h): D7 D6 D5 Busy D4 D3 D2 Reserved 0 0 0 0 D1 D0 RD2M RD1M 0 Bits Name Description 7 Busy When set to "1" the part is converting. 6-2 Reserved Reports "0" when read. 1 Remote diode 2 missing (RD2M) Remote Diode 2 is missing. (i.e. D2+ shorted to VDD, Ground or D2-, or D2+ is floating). Temperature Reading is FFE0h which converts to 255.
PAGE 13
LM95221 2.0 LM95221 Registers (Continued) 2.3 LOCAL and REMOTE MSB and LSB TEMPERATURE REGISTERS Local Temperature MSB (Read Only Address 10h) 9-bit plus sign format: BIT D7 D6 D5 D4 D3 D2 D1 D0 Value SIGN 64 32 16 8 4 2 1 Temperature Data: LSb = 1˚C. Local Temperature LSB (Read Only Address 20h) 9-bit plus sign format: BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 0.5 0.25 0 0 0 0 0 0 Temperature Data: LSb = 0.25˚C.
PAGE 14
LM95221 • VBE = Base Emitter Voltage drop In the active region, the -1 term is negligible and may be eliminated, yielding the following equation 3.0 Applications Hints The LM95221 can be applied easily in the same way as other integrated-circuit temperature sensors, and its remote diode sensing capability allows it to be used in new ways as well.
PAGE 15
possible to the LM95221’s D+ and D− pins. Make sure the traces to the 2.2nF capacitor are matched. (Continued) 3.1.2 Compensating for Diode Non-Ideality In order to compensate for the errors introduced by nonideality, the temperature sensor is calibrated for a particular processor. National Semiconductor temperature sensors are always calibrated to the typical non-ideality of a given processor type. The LM95221 is calibrated for a non-ideality of 1.008 and a series resistance of 2.7Ω.
PAGE 16
LM95221 Dual Remote Diode Digital Temperature Sensor with SMBus Interface Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead Molded Mini-Small-Outline Package (MSOP), JEDEC Registration Number MO-187 Order Number LM95221CIMM or LM95221CIMMX NS Package Number MUA08A 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 COUNSEL OF NATIONAL SEMICONDUCT