LM99
1C Accurate, High Temperature, Remote Diode
Temperature Sensor with Two-Wire Interface
General Description
The LM99 is an 11-bit remote diode temperature sensor with
a 2-wire System Management Bus (SMBus) serial interface.
The LM99 accurately measures: (1) its own temperature and
(2) the temperature of a remote diode-connected transistor
such as the 2N3904 or a thermal diode commonly found on
Graphics Processor Units (GPU), Computer Processor Units
(CPU or other ASICs. The LM99 remote diode temperature
sensor shifts the temperature from the remote sensor down
16C and operates on that shifted temperature:
T
ACTUAL DIODE JUNCTION
= T
LM99
+ 16C
The local temperature reading requires no offset.
The LM99 has an Offset Register which provides a means
for precise matching to various thermal diodes. Contact
hardware.monitor
@
nsc.com for the latest details.
The LM99 and LM99-1 have the same functions but different
SMBus slave addresses. This allows for one of each to be on
the same bus at the same time.
Activation of the ALERT output occurs when any tempera-
ture goes outside a preprogrammed window set by the HIGH
and LOW temperature limit registers or exceeds the T_CRIT
temperature limit. Activation of the T_CRIT_A occurs when
any temperature exceeds the T_CRIT programmed limit.
Features
n
Accurately senses the temperature of remote diodes
n
Offset register allows use of a variety of thermal diodes
n
On-board local temperature sensing
n
10 bit plus sign remote diode temperature data format,
0.125 C resolution
n
T_CRIT_A output useful for system shutdown
n
ALERT output supports SMBus 2.0 protocol
n
SMBus 2.0 compatible interface, supports TIMEOUT
n
8-pin MSOP package
Key Specifications
j
Supply Voltage
3.0 V to 3.6 V
j
Supply Current
0.8 mA (typ)
j
Local Temp Accuracy (includes quantization error)
T
A
= 25C to 125C
3.0C (max)
j
Remote Diode Temp Accuracy (includes quantization
error)
T
A
= 30C to 50C, T
D
= 120C to 140C
1.0C (max)
T
A
= 0C to 85C, T
D
= 25C to 140C
3.0C (max)
Applications
n
Graphics Processor Thermal Management
n
Computer Processor Thermal Management
n
Electronic Test Equipment
n
Office Electronics
Simplified Block Diagram
20053801
NVIDIA
is a registered trademark of NVIDIA Corporation.
GeForce
TM
is a trademark of NVIDIA Corporation.
Intel
and Pentium
are registered trademarks of Intel Corporation.
July 2003
LM99
1C
Accurate,
High
T
emperature,
Remote
Diode
T
emperature
Sensor
with
T
wo-W
ire
Interface
2003 National Semiconductor Corporation
DS200538
www.national.com
Connection Diagram
MSOP-8
20053802
TOP VIEW
Ordering Information
Part Number
Package
Marking
NS Package
Number
Transport
Media
LM99CIMM
T17C
MUA08A
(MSOP-8)
1000 Units on
Tape and Reel
LM99-1CIMM
T20C
MUA08A
(MSOP-8)
1000 Units on
Tape and Reel
LM99CIMMX
T17C
MUA08A
(MSOP-8)
3500 Units on
Tape and Reel
LM99-1CIMMX
T20C
MUA08A
(MSOP-8)
3500 Units on
Tape and Reel
Pin Descriptions
Label
Pin #
Function
Typical Connection
V
DD
1
Positive Supply Voltage Input
DC Voltage from 3.0 V to 3.6 V. V
DD
should be bypassed
with a 0.1 F capacitor in parallel with 100 pF to ground.
The 100 pF capacitor should be placed as close as
possible to the power supply pin. A bulk capacitance of
approximately 10 F needs to be in the vicinity of the LM99
V
DD
.
D+
2
Diode Current Source
To Diode Anode. Connected to the collector and base of
the remote discrete diode-connected transistor. Connect a
2.2 nF capacitor between pins 2 and 3.
D-
3
Diode Return Current Sink
To Diode Cathode. Connects to the emitter of the remote
diode-connected transistor. Connect a 2.2 nF capacitor
between pins 2 and 3.
T_CRIT_A
4
T_CRIT Alarm Output,
Open-Drain, Active-Low
Pull-Up Resistor, Controller Interrupt or Power Supply
Shutdown Control
GND
5
Power Supply Ground
Ground
ALERT
6
Interrupt Output, Open-Drain,
Active-Low
Pull-Up Resistor, Controller Interrupt or Alert Line
SMBData
7
SMBus Bi-Directional Data
Line, Open-Drain Output
From and to Controller, Pull-Up Resistor
SMBCLK
8
SMBus Input
From Controller, Pull-Up Resistor
LM99
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2
Typical Application
20053803
LM99
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3
Absolute Maximum Ratings
(Note 1)
Supply Voltage
-0.3 V to 6.0 V
Voltage at SMBData, SMBCLK,
ALERT, T_CRIT_A
-0.5 V to 6.0 V
Voltage at Other Pins
-0.3 V to
(V
DD
+ 0.3 V)
D- Input Current
1 mA
Input Current at All Other Pins
(Note 2)
5 mA
Package Input Current
(Note 2)
30 mA
SMBData, ALERT, T_CRIT_A Output
Sink Current
10 mA
Storage Temperature
-65C to
+150C
Soldering Information, Lead Temperature
MSOP-8 Packages (Note 3)
Vapor Phase (60 seconds)
215C
Infrared (15 seconds)
220C
ESD Susceptibility (Note 4)
Human Body Model
2000 V
Machine Model
200 V
Operating Ratings
(Notes 1, 5)
Operating Temperature Range
0C to +125C
Electrical Characteristics
Temperature Range
T
MIN
T
A
T
MAX
LM99
0C
T
A
+85C
Supply Voltage Range (V
DD
)
+3.0 V to +3.6 V
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for V
DD
= +3.0 Vdc to +3.6 Vdc. Boldface limits apply for T
A
= T
J
= T
MIN
T
A
T
MAX
; all other limits T
A
= T
J
= +25C, unless otherwise noted.
Parameter
Conditions
Typical
Limits
Units
(Note 6)
(Note 7)
(Limit)
Temperature Error Using Local Diode
T
A
= +25C to +125C, (Note 8)
1
3
C (max)
Temperature Error Using Remote Diode
Connected Transistor (T
D
is the Remote
Diode Junction Temperature)
T
D
= T
LM99
+ 16C
T
A
= +30C to +50C and T
D
=
+120C to +140C
1
C (max)
T
A
= +0C to +85C and T
D
=
+25C to +140C
3
C (max)
Remote Diode Measurement Resolution
11
Bits
0.125
C
Local Diode Measurement Resolution
8
Bits
1
C
Conversion Time of All Temperatures at the
Fastest Setting
(Note 10)
31.25
34.4
ms (max)
Quiescent Current (Note 9)
SMBus Inactive, 16 Hz
conversion rate
0.8
1.7
mA (max)
Shutdown
315
A
D- Source Voltage
0.7
V
Diode Source Current
(V
D+
- V
D-
) = + 0.65 V; high
level
160
315
A (max)
110
A (min)
Low level
13
20
A (max)
7
A (min)
ALERT and T_CRIT_A Output Saturation
Voltage
I
OUT
= 6.0 mA
0.4
V (max)
Power-On-Reset (POR) Threshold
Measure on V
DD
input, falling
edge
2.4
1.8
V (max)
V (min)
Local and Remote HIGH Default Temperature
settings
(Note 11) Add 16C for true
Remote Temperature.
+70
C
Local and Remote LOW Default Temperature
settings
(Note 11) Add 16C for true
Remote Temperature.
0
C
Local T_CRIT Default Temperature Setting
(Note 11)
+85
C
Remote T_CRIT Default Temperature Setting
(Note 11) Add 16C for 126C
true Remote T_CRIT Setting
+110
C
LM99
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4
Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for V
DD
= +3.0 to 3.6 Vdc. Boldface
limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C, unless otherwise noted.
Symbol
Parameter
Conditions
Typical
Limits
Units
(Note 6)
(Note 7)
(Limit)
SMBData, SMBCLK INPUTS
V
IN(1)
Logical "1" Input Voltage
2.1
V (min)
V
IN(0)
Logical "0"Input Voltage
0.8
V (max)
V
IN(HYST)
SMBData and SMBCLK Digital
Input Hysteresis
400
mV
I
IN(1)
Logical "1" Input Current
V
IN
= V
DD
0.005
10
A (max)
I
IN(0)
Logical "0" Input Current
V
IN
= 0 V
-0.005
10
A (max)
C
IN
Input Capacitance
5
pF
ALL DIGITAL OUTPUTS
I
OH
High Level Output Current
V
OH
= V
DD
10
A (max)
V
OL
SMBus Low Level Output Voltage
I
OL
= 4 mA
I
OL
= 6 mA
0.4
0.6
V (max)
SMBus Digital Switching Characteristics
Unless otherwise noted, these specifications apply for V
DD
= +3.0 Vdc to +3.6 Vdc, C
L
(load capacitance) on output lines = 80
pF. Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25C, unless otherwise noted. The switch-
ing characteristics of the LM99 fully meet or exceed the published specifications of the SMBus version 2.0. The following pa-
rameters are the timing relationships between SMBCLK and SMBData signals related to the LM99. They adhere to but are not
necessarily the SMBus bus specifications.
Symbol
Parameter
Conditions
Typical
Limits
Units
(Note 6)
(Note 7)
(Limit)
f
SMB
SMBus Clock Frequency
100
10
kHz (max)
kHz (min)
t
LOW
SMBus Clock Low Time
from V
IN(0)
max to
V
IN(0)
max
4.7
25
s (min)
ms (max)
t
HIGH
SMBus Clock High Time
from V
IN(1)
min to V
IN(1)
min
4.0
s (min)
t
R,SMB
SMBus Rise Time
(Note 12)
1
s (max)
t
F,SMB
SMBus Fall Time
(Note 13)
0.3
s (max)
t
OF
Output Fall Time
C
L
= 400 pF,
I
O
= 3 mA, (Note 13)
250
ns (max)
t
TIMEOUT
SMBData and SMBCLK Time Low for
Reset of Serial Interface (Note 14)
25
35
ms (min)
ms (max)
t
SU;DAT
Data In Setup Time to SMBCLK High
250
ns (min)
t
HD;DAT
Data Out Stable after SMBCLK Low
300
900
ns (min)
ns (max)
t
HD;STA
Start Condition SMBData Low to SMBCLK
Low (Start condition hold before the first
clock falling edge)
100
ns (min)
t
SU;STO
Stop Condition SMBCLK High to SMBData
Low (Stop Condition Setup)
100
ns (min)
t
SU;STA
SMBus Repeated Start-Condition Setup
Time, SMBCLK High to SMBData Low
0.6
s (min)
t
BUF
SMBus Free Time Between Stop and Start
Conditions
1.3
s (min)
LM99
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