LM88CIMMX-B [NSC]
Factory Programmable Dual Remote-Diode Thermostat; 工厂可编程双路远程二极管温控器
| 型号： | LM88CIMMX-B |
| 厂家： | 
National Semiconductor |
| 描述： | Factory Programmable Dual Remote-Diode Thermostat |
| 文件： | 总9页 (文件大小：199K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
August 2001
LM88
Factory Programmable Dual Remote-Diode Thermostat
General Description
Features
n 2 external remote diode input channels
n 3 digital comparator outputs, 1 per remote diode and
one T_CRIT common to both
The LM88 is a dual remote-diode temperature sensor with 3
digital comparators. The LM88 has 3 open-drain outputs
(O_SP0, O_SP1 and O_CRIT) that can be used as inter-
rupts or to signal system shutdown. The digital comparators
can be factory programmed to make a greater than or less
than comparison. When programmed for a greater than
comparison outputs:
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
O_SP0 and O_SP1 activate when the temperatures mea-
sured by D0 or D1 exceed the associated setpoints of
T_SP0 or T_SP1.
O_CRIT activates when the temperature measured by
either D0 or D1 exceeds setpoint T_CRIT.
n Active Low open-drain digital outputs
n 8-pin mini-SO plastic package
T_CRIT can be set at 1˚C intervals from −40˚C to +125˚C.
T_SP0 and T_SP1 can be set at 4˚C intervals in the range of
T_CRIT +127˚C/−128˚C. Hysteresis for all comparators is
set to 1˚C. O_CRIT, in conjunction with T_CRIT, could be
used to prevent catastrophic damage to key subsystems
such as notebook Card Bus cards while O_SP0 and O_SP1,
in conjunction with T_SP0 and T_SP1, can warn of an
impending failure.
Key Specifications
j
j
j
j
Power Supply Voltage
2.8V–3.8V
1.5 mA (max)
−40˚C to +85˚C
Power Supply Current
LM88 Temperature Range
Diode Setpoint Temperature
Range
0˚C to +125˚C
The LM88 is available in an 8-lead mini-small-outline pack-
age.
j
Temperature Trip Point Accuracy:
Diode Junction
Temperature
LM88CIM
Accuracy
LM88CIM
Temperature
Range
Applications
n Microprocessor Thermal Management
n Appliances
(TDJ
)
n Portable Battery Powered Systems
n Fan Control
n Industrial Process Control
n HVAC Systems
n Remote Temperature Sensing
n Electronic System Protection
±
+45˚C to +85˚C
+60˚C to +100˚C
3˚C (max)
3˚C (max)
−40˚C to +85˚C
−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
10132602
For simplicity, the effects of the hysteresis are not shown in the
temperature response diagram.
Top View
© 2001 National Semiconductor Corporation
DS101326
www.national.com
Simplified Block Diagram and Connection Diagram (Continued)
Order Number
Device
NS Package
Number
Transport
Media
T_SP0
(˚C)
T_SP1
(˚C)
T_CRIT
(˚C)
S etpoint
Accuracy
(˚C)
Marking
LM88CIMM-A
Rail
Tape and
Real
MUA08A
or
±
±
T08A
T08A
61
41
49
49
80
60
3
3
LM88CIMMX-A
MSOP-8
LM88CIMM-B
Rail
MUA08A
or
LM88CIMMX-B
Tape and
Real
MSOP-8
For other setpoints please contact the factory. Performance is dependent on temperature range.
Typical Application
10132613
FIGURE 1. Thermal Protection for Pentium® Processor and Graphics Chip
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2
Absolute Maximum Ratings (Note 1)
Operating Ratings(Note 1)
Input Voltage
6V
Operating Temperature
Range
TMIN ≤ T ≤ TMAX
−40˚C ≤ TA ≤ +85˚C
0˚C ≤ TDJ ≤ +125˚C
+2.8V to +3.8V
Input Current at any pin (Note 2)
Package Input Current (Note 2)
Package Dissipation at TA = 25˚C
(Note 4)
5mA
LM88CIMM
20mA
Remote Diode Junction
Positive Supply Voltage (V+)
900mW
Soldering Information
Maximum V O_CRIT, V
O_SP0
and V
+5.5V
MSOP Package (Note 6) :
Vapor Phase (60 seconds)
Infrared (15 seconds)
O_SP1
215˚C
220˚C
Storage Temperature
−65˚C to + 150˚C
ESD Susceptibility (Note 5)
Human Body Model
Machine Model
2500V
250V
LM88 Electrical Characteristics
The following specifications apply for 2.8VDC≤V+ ≤ 3.8VDC unless otherwise specified. Boldface limits apply for TA = TJ
TMIN to TMAX; all other limits TA = TJ = 25˚C unless otherwise specified.
=
Typical
LM88CIMM
Limits
Units
Symbol
Parameter
Conditions
(Note 7)
(Limits)
(Note 8)
Temperature Sensor
±
Setpoint Temperature Accuracy (Note 9)
+60˚C ≤ TDJ ≤ +100˚C
+45˚C ≤ TDJ ≤ +85˚C
+30˚C ≤ TDJ ≤ +70˚C
3
˚C (max)
Setpoint Hysteresis
Output Update Rate
1
˚C (min)
˚C (max)
ms (max)
1
920
VD−, VD0 and VD1 Analog Inputs
ID+SOURCE Diode Source Current
(D+ − D−)=0.65; high
level
120
12
210
46
µA (max)
µA (min)
µA (max)
µA (min)
V
(D+ − D−)=0.65; low
level
21
4.6
VD−Out
D− Output Source Voltage
0.7
LM88 Electrical Characteristics
The following specifications apply for 2.8VDC≤V+ ≤ 3.8VDC unless otherwise specified. Boldface limits apply for TA = TJ
TMIN to TMAX; all other limits TA = TJ = 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)
µA (max)
V (max)
V
OUT=V+ =3.8V to
40
0.4
2.8V
VOUT(“0”)
Logical “0” Output Voltage
IOUT = +3 mA
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.
3
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LM88 Electrical Characteristics (Continued)
+
<
>
V ), the current at that pin should be limited to 5mA. The 20mA
Note 2: When the input voltage (V ) at any pin exceeds the power supply (V
GND or V
I
I
I
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
D0+
D1
X
D2
X
D3
X
D4
X
D5
X
D6
X
R1
50Ω
50Ω
50Ω
0Ω
D−
X
X
X
X
X
D1+
X
X
X
X
X
O_CRIT
O_SP1
O_SP0
X
X
X
X
X
X
X
X
0Ω
X
X
X
X
0Ω
10132604
Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
(maximum junction temperature), θ (junction to
JA
Jmax
ambient thermal resistance) and T (ambient temperature). The maximum allowable power dissipation at any temperature is P = (T
–T )/θ or the number
A JA
A
D
Jmax
given in the Absolute Maximum Ratings, whichever is lower. For this device, T
= 125˚C. For this device the typical thermal resistance (θ ) of the different
Jmax
JA
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 T = T = 25˚C and represent most likely parametric norm.
J
A
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 I specifications are intended to describe two operating regions of the output voltage. In Region 1, V − 0.6V and below, there is normal leakage
OH
+
+
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 may flow causing
less than 22mV of voltage drop.
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4
1.0 Functional Description
10132611
a) When programmed for a greater than comparison
10132612
b) When programmed for a less than comparison
FIGURE 2. Comparator output temperature response diagrams
±
dition, to T_CRIT 1˚C is false. The CRIT com-
1.1 PIN DESCRIPTIONS
V+
This is the positive supply voltage pin, which has
a range of 2.8 to 3.8 volts. This pin should be
bypassed with a 0.1µF capacitor to ground.
parator can be factory programmed to make a
greater than or less than comparison. (See Sec-
tion 1.3 LM88 OPTIONS)
O_SP1
This is an active-low open-drain digital output. It
goes LOW when the comparison of the tempera-
ture reading of diode one to the value of T_SP1 is
true. The SP1 comparator has a built in hyster-
esis of 1˚C. Therefore, O_SP1 returns to HIGH
when diode one’s temperature comparison to the
GND
This is the ground pin.
D0+, D1+ These pins connect to the positive terminal of the
diodes (e.g. a 2N3904 collector base shorted or a
Pentium thermal diode anode) and provide the
source current for forward biasing the diodes for
the temperature measurement. During a tem-
perature conversion, the current source switches
between 120µA and 12µA. The diodes are
sampled sequentially.
±
value of T_SP1 1˚C is false. The SP1 compara-
tor can be factory programmed to make a greater
than or less than comparison.(See Section 1.3
LM88 OPTIONS)
D−
This pin should be connected to the negative pin
of each diode (e.g. a 2N3904 emitter or a Pen-
tium thermal diode cathode). A star connection is
recommended. Separate traces should be routed
from this pin to each diode cathode. This pin
biases the negative diode terminals to approxi-
mately 0.7V.
O_SP0
This is an active-low open-drain digital output. It
goes LOW when the comparison of the tempera-
ture reading of diode one to the value of T_SP0 is
true. The SP0 comparator has a built in hyster-
esis of 1˚C. Therefore, O_SP0 returns to HIGH
when diode one’s temperature comparison to the
±
value of T_SP0 1˚C is false. The SP0 compara-
O_CRIT This is an active-low open-drain digital output. It
goes LOW when a comparison of either diode
temperature reading to the setpoint T_CRIT is
true. It returns to HIGH when the comparison of
the diode temperature, that caused the true con-
tor can be factory programmed to make a greater
than or less than comparison.(See Section 1.3
LM88 OPTIONS)
5
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1.0 Functional Description (Continued)
1.2 TYPICAL PIN CONNECTION
Pin Label
D0+
Pin Number
1
Typical Connection
3904-type transistor
shorted-collector base or
Pentium thermal diode anode;
2.2nF capacitor connected to
D-
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-
a quiet system ground
2k pull-up; system shutdown
or the THERM pin of the ICH
(I/O Controller Hub found in
PCs)
GND
4
5
O_CRIT
O_SP1
O_SP1
6
7
8
2k pull-up; general purpose
input (GPI), to determine
which diode caused the
THERM event
2k pull-up; general purpose
input (GPI), to determine
which diode caused the
THERM event
V+
3.3V; 0.1µF bypass capacitor
1.3 LM88 OPTIONS
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.
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
2.0 Application Hints
where:
a and b are any integer in the range of −32 to +31.
2.1 OPEN-DRAIN OUTPUTS
T_CRIT can be any value in the range of 0˚C to +125˚C with
a resolution of 1˚C.
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.
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
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
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6
temperature sensor. The only other parameter is η, which
depends on the diode that is used for measurement. Since
∆VBE is proportional to both η and T, the variations in η
cannot be distinguished from variations in temperature.
Since the non-ideality factor is not controlled by the tempera-
ture sensor, it will directly add to the inaccuracy of the
2.0 Application Hints (Continued)
of the LM88’s temperature. The LM88 has been optimized to
measure the remote diode of a Pentium type processor as
shown in Figure 3. A discrete diode can also be used to
sense the temperature of external objects or ambient air.
Remember that a discrete diode’s temperature will be af-
fected, and often dominated, by the temperature of its leads.
±
sensor. For the Pentium II, Intel specifies a 1% variation in
η from part to part. As an example, assume a temperature
±
sensor has an accuracy specification of 3 ˚C at room
As with any IC, the LM88 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 ensure that moisture
cannot corrode the LM88 or its connections. Moisture may
also cause leakage on the diode wiring and therefore affect
the accuracy of the temperature set-points.
temperature of 25 ˚C and the process used to manufacture
the diode has a non-ideality variation of 1%. The resulting
accuracy of the temperature sensor at room temperature will
be:
±
± ± ±
3˚C + ( 1% of 298 ˚K) = 6˚C
TACC
=
.
The additional inaccuracy in the temperature measurement
caused by η can be eliminated if each temperature sensor is
calibrated with the remote diode that it will be paired with.
2.4 PCB LAYOUT to MINIMIZE NOISE
In a noisy environment, such as a processor motherboard,
layout considerations are very critical. Noise induced on
traces running between the remote temperature diode sen-
sor and the LM88 can cause temperature conversion errors.
The following guidelines should be followed:
1. Place a 0.1 µF power supply bypass capacitor as close
as possible to the VDD pin and the recommended 2.2 nF
capacitor as close as possible to the D+ and D− pins.
Make sure the traces to the two 2.2nF capacitor are
matched.
10132615
2. The recommended 2.2nF diode bypass capacitor actu-
ally has a range of 200pF to 3.3nF. The average tem-
perature accuracy will not change over that capacitance
range. Increasing the capacitance will lower the corner
frequency where differential noise error will start to affect
the temperature reading thus producing a reading that is
more stable. Conversely, lowering the capacitance will
increase the corner frequency where differential noise
error starts to affect the temperature reading thus pro-
ducing a reading that is less stable.
FIGURE 3. Pentium or 3904 Temperature vs LM88
Temperature Set-point
Most silicon diodes do not lend themselves well to this
application. It is recommended that a 2N3904 transistor
base emitter junction be used with the collector tied to the
base.
A diode connected 2N3904 approximates the junction avail-
able on a Pentium III microprocessor for temperature mea-
surement. Therefore, the LM88 can sense the temperature
of this diode effectively.
3. Ideally, the LM88 should be placed within 10cm of the
remote diode pins with the traces being as straight, short
and identical as possible. Trace resistance of 1Ω can
cause as much as 1˚C of error. This error can be com-
pensated by using the Remote Temperature Offset Reg-
isters, since the value placed in these registers will
automatically be subtracted or added to the remote tem-
perature reading.
2.3 EFFECTS OF THE DIODE NON-IDEALITY FACTOR
ON ACCURACY
The technique used in today’s remote temperature sensors
is to measure the change in VBE at two different operating
points of a diode. For a bias current ratio of N:1, this differ-
ence is given as:
4. Diode traces should be surrounded by a GND guard ring
to either side, above and below if possible. This GND
guard should not go between the D+ and D− lines so
that in the event that noise does couple to the diode
lines, it would be coupled common mode and rejected-
.(See Figure 4)
where:
5. Avoid routing diode traces in close proximity to power
supply switching or filtering inductors.
— η is the non-ideality factor of the process the diode is
manufactured on,
6. Avoid running diode traces close to or parallel to high
speed digital and bus lines. Diode traces should be kept
at least 2cm apart from the high speed digital traces.
— q is the electron charge,
— k is the Boltzmann’s constant,
— N is the current ratio,
7. If it is necessary to cross high speed digital traces, the
diode traces and the high speed digital traces should
cross at a 90 degree angle.
— T is the absolute temperature in ˚K.
The temperature sensor then measures ∆VBE and converts
to IT digital data. In this equation, k and q are well defined
universal constants, and N is a parameter controlled by the
7
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as much as 1˚C of error in the diode temperature read-
ing. Keeping the printed circuit board as clean as pos-
sible will minimize leakage current.
2.0 Application Hints (Continued)
8. The ideal place to connect the LM88’s GND pin is as
close as possible to the processor GND associated with
the sense diode.
9. Leakage current between D+ and GND should be kept
to a minimum. One nano-ampere of leakage can cause
10132633
FIGURE 4. Ideal Diode Trace Layout
3.0 Applications Circuits
10132614
FIGURE 5. Pentium processor Thermal Management with Fan Control
10132603
FIGURE 6. Card Bus Thermal Management
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8
Physical Dimensions inches (millimeters)
unless otherwise noted
8-Lead Molded Mini Small Outline Package (MSOP)
(JEDEC REGISTRATION NUMBER M0-187)
Order Number LM88CIMM, or LM88CIMMX
NS Package Number MUA08A
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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
National Semiconductor
Europe
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
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Tel: 81-3-5639-7560
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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.
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