LM88 NSC | Alldatasheet
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Technical content
Features
n 2 external remote diode input channels n 3 digital comparator outputs, 1 per remote diode and one T_CRIT common to both n Factory programmable greater than or less than comparisons n 1˚C comparator hysteresis n 2 setpoints, T_SP0 and T_SP1, factory programmable in 4˚C intervals n 1 setpoint, T_CRIT, factory programmable in 1˚C intervals n Active Low open-drain digital outputs n 8-pin mini-SO plastic package Key Specifications j Power Supply Voltage 2.8V–3.8V j Power Supply Current 1.5 mA (max) j LM88 Temperature Range −40˚C to +85˚C j Diode Setpoint Temperature Range 0˚C to +125˚C j Temperature Trip Point Accuracy: Diode Junction Temperature (TDJ ) LM88CIM Accuracy LM88CIM Temperature Range +45˚C to +85˚C ±3˚C (max) −40˚C to +85˚C +60˚C to +100˚C ±3˚C (max) −40˚C to +85˚C Note: These are sample ranges. Contact factory for other ranges. Simplified Block Diagram and Connection Diagram MSOP-8/MUA08A Package 10132601 Top View 10132602 For simplicity, the effects of the hysteresis are not shown in the temperature response diagram. August 2001 LM88 Factory Programmable Dual Remote-Diode Thermostat © 2001 National Semiconductor Corporation DS101326 www.national.com
For other setpoints please contact the factory. Performance is dependent on temperature range. FIGURE 1. Thermal Protection for Pentium® Processor and Graphics Chip
Absolute Maximum Ratings (Note 1) Input Voltage 6V Input Current at any pin (Note 2) 5mA Package Input Current (Note 2) 20mA Package Dissipation at T A = 25˚C (Note 4) 900mW Soldering Information Vapor Phase (60 seconds) 215˚C Infrared (15 seconds) 220˚C Storage Temperature −65˚C to + 150˚C ESD Susceptibility (Note 5) Human Body Model Machine Model 2500V 250V Operating Ratings(Note 1) Operating Temperature Range TMIN ≤ T ≤ TMAX LM88CIMM −40˚C ≤ TA ≤ +85˚C Remote Diode Junction 0˚C ≤ TDJ ≤ +125˚C Positive Supply Voltage (V+) +2.8V to +3.8V Maximum V O_CRIT ,V O_SP0 and V O_SP1 +5.5V The following specifications apply for 2.8VDC ≤V+ ≤ 3.8VDC unless otherwise specified.Boldface limits apply for TA =T J = TMIN to TMAX ;all other limits TA =T J = 25˚C unless otherwise specified. Typical LM88CIMM Units Symbol Parameter Conditions (Note 7) Limits (Limits) (Note 8) Temperature Sensor Setpoint Temperature Accuracy (Note 9) +60˚C ≤ TDJ ≤ +100˚C ±3 ˚C (max) +45˚C ≤ TDJ ≤ +85˚C +30˚C ≤ TDJ ≤ +70˚C Setpoint Hysteresis 1 ˚C (min) 1 ˚C (max) Output Update Rate 920 ms (max) VD− ,V D0 and VD1 Analog Inputs ID+SOURCE Diode Source Current (D+ − D−)=0.65; high level 120 210 µA (max) 46 µA (min) (D+ − D−)=0.65; low level 12 21 µA (max) 4.6 µA (min) VD−Out D− Output Source Voltage 0.7 V The following specifications apply for 2.8VDC ≤V+ ≤ 3.8VDC unless otherwise specified.Boldface limits apply for TA =T J = TMIN to TMAX ;all other limits TA =T J = 25˚C unless otherwise specified. Symbol Parameter Conditions Typical Limits Units (Note 7) (Note 8) (Limits) V+ Power Supply IS Supply Current 1.5 mA (max) Digital Outputs IOUT(“1”) Logical “1” Output Leakage Current (Note 10) VOUT =V +− 0.6V where V+=3.8V to 2.8V 2 µA (max) VOUT =V + =3.8V to 2.8V 40 µA (max) VOUT(“0”) Logical “0” Output Voltage I OUT =+ 3m A 0.4 V (max) Note 1:Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. LM88 www.national.com3
Note 2:When the input voltage (VI) at any pin exceeds the power supply (VI < GND or VI > V+), the current at that pin should be limited to 5mA. The 20mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5mA to four. Note 3:Parasitics or ESD protection circuitry are shown in the diagram found below. The ESD Clamp circtuitry is triggered on when there is an ESD event. The table maps what devices appear on the different pins. Pin Name D1 D2 D3 D4 D5 D6 R1 D 0 + XXXX X 5 0 Ω D − XXXXXX 5 0 Ω D 1 + XXXX X 5 0 Ω O_CRIT XXXX 0 Ω O_SP1 XXXX 0 Ω O_SP0 XXXX 0 Ω 10132604 Note 4:The maximum power dissipation must be derated at elevated temperatures and is dictated by TJmax (maximum junction temperature),θJA (junction to ambient thermal resistance) and TA (ambient temperature). The maximum allowable power dissipation at any temperature is PD =( TJmax –TA)/θJA or the number given in the Absolute Maximum Ratings, whichever is lower. For this device, TJmax = 125˚C. For this device the typical thermal resistance (θJA) of the different package types when board mounted follow: Package Type θJA MUA08A 250˚C/W Note 5:The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. The machine model is a 200pF capacitor discharged directly into each pin. Note 6:See the URL ”http://www.national.com/packaging/“ for other recomdations and methods of soldering surface mount devices. Note 7:Typicals are at TJ =T A = 25˚C and represent most likely parametric norm. Note 8:Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 9:These are sample temperature ranges, contact the factory for other temperature ranges. Performance is dependent on temperature range. Note 10:The two IOH specifications are intended to describe two operating regions of the output voltage. In Region 1, V+− 0.6V and below, there is normal leakage current, 2µA (max). In Region 2, V+− 0.6V to V+, there is additional current flowing caused by the ESD protection circuitry (see Figure in Note 3). The maximum current flow is under short circuit conditions as specified at 40µA (max). Under normal operating conditions a pull-resistor (R) will be used. The voltage drop across this pull-up resistor caused by the 2µA normal leakage current with large values of R (much greater than 100k) will bias diode D1 into the cutoff region causing the additional current to be negligible in the voltage drop calculation. With low values of R more current will flow as in the case of a 1.1k pull-up, 20µA mayflow causing less than 22mV of voltage drop. LM88 www.national.com 4
1.0 Functional Description
1.1 PIN DESCRIPTIONS
bypassed with a 0.1µF capacitor to ground. FIGURE 2. Comparator output temperature response diagrams
1.0 Functional Description(Continued)
1.2 TYPICAL PIN CONNECTION
Pin Label Pin Number Typical Connection D0+ 1 3904-type transistor shorted-collector base or Pentium thermal diode anode; 2.2nF capacitor connected to D− 2 3904-type transistor emitter or Pentium thermal diode cathode (individual traces are required to each diode; do not daisy chain); two 2.2nF capacitors connected to D0+ and D1+ D1+ 3 3904-type transistor shorted collector-base or Pentium thermal diode anode; 2.2nF capacitor connected to D- GND 4 a quiet system ground O_CRIT 5 2k pull-up; system shutdown or the THERM pin of the ICH (I/O Controller Hub found in PCs) O_SP1 6 2k pull-up; general purpose input (GPI), to determine which diode caused the THERM event O_SP1 7 2k pull-up; general purpose input (GPI), to determine which diode caused the THERM event V + 8 3.3V; 0.1µF bypass capacitor
1.3 LM88 OPTIONS
1.3.1 Set-Point Values
T_SP0 and T_SP1 are dependent on the value of T_CRIT: T_SP0 = T_CRIT + 4a + 1 T_SP1 = T_CRIT + 4b + 1 where: a and b are any integer in the range of −32 to +31. T_CRIT can be any value in the range of 0˚C to +125˚C with a resolution of 1˚C.
1.3.2 Functionality
The LM88’s comparators can be factory programmed to do a greater than or less than comparison. When programmed for a greater than comparison, the comparison result is true when the temperature measured is above the prepro- grammed setpoint temperature. The comparison returns to false when the temperature measured is below or equal to the setpoint temperature minus one degree. For a less than comparison the comparison result is true when the tempera- ture measured is below the preprogrammed limit. The result turns to false when the temperature measured is above or equal to the setpoint limit plus one degree. SP0, SP1 and CRIT comparisons can all be independently programmed to be greater than or less than. All CRIT comparisons are required to be the same, either greater than or less than. The comparator hysteresis can also be factory set to one, two or three degrees. The hysteresis for all comparisons is required to be the same.
2.0 Application Hints
2.1 OPEN-DRAIN OUTPUTS
The O_SP0, O_SP1 and 0_CRIT outputs are open-drain outputs and do not have internal pull-ups. A “high” level will not be observed on these pins until pull-up current is pro- vided from some external source, typically a pull-up resistor. Choice of resistor value depends on many system factors but, in general, the pull-up resistor should be as large as possible. This will minimize any internal temperature reading errors due to internal heating of the LM88. The maximum resistance of the pull-up needed to provide a 2.1V high level, based on LM88 specification for High Level Output Current with the supply voltage at 3.0V, is 430kΩ .
2.2 THERMAL DIODE MOUNTING CONSIDERATIONS
To measure temperature the LM88 uses two remote diodes. These diodes can be located on the die of a target IC, allowing measurement of the IC’s temperature, independent LM88 www.national.com 6
2.0 Application Hints(Continued)
Figure 3. A discrete diode can also be used to sense the temperature of external objects or ambient air. fected, and often dominated, by the temperature of its leads. cold temperatures where condensation can occur. the accuracy of the temperature set-points.
2.3 EFFECTS OF THE DIODE NON-IDEALITY FACTOR
— T is the absolute temperature in ˚K. cannot be distinguished from variations in temperature. calibrated with the remote diode that it will be paired with.
2.4 PCB LAYOUT to MINIMIZE NOISE
sor and the LM88 can cause temperature conversion errors.
- Place a 0.1 µF power supply bypass capacitor as close
capacitor as close as possible to the D+ and D− pins.
- The recommended 2.2nF diode bypass capacitor actu-
ducing a reading that is less stable.
- Ideally, the LM88 should be placed within 10cm of the
- Diode traces should be surrounded by a GND guard ring
- Avoid routing diode traces in close proximity to power
supply switching or filtering inductors.
- Avoid running diode traces close to or parallel to high
at least 2cm apart from the high speed digital traces.
- If it is necessary to cross high speed digital traces, the
FIGURE 3. Pentium or 3904 Temperature vs LM88
- The ideal place to connect the LM88’s GND pin is as
- Leakage current between D+ and GND should be kept
sible will minimize leakage current.
3.0 Applications Circuits
FIGURE 4. Ideal Diode Trace Layout FIGURE 5. Pentium processor Thermal Management with Fan Control FIGURE 6. Card Bus Thermal Management
Physical Dimensionsinches (millimeters) unless otherwise noted 8-Lead Molded Mini Small Outline Package (MSOP) (JEDEC REGISTRATION NUMBER M0-187) Order Number LM88CIMM, or LM88CIMMX 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 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. National Semiconductor Corporation Americas Email: support@nsc.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: ap.support@nsc.com National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 www.national.com LM88 Factory Programmable Dual Remote-Diode Thermostat 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.