LM84
Diode Input Digital Temperature Sensor with Two-Wire
Interface
General Description
The
LM84
is
a
remote
diode
temperature
sensor,
Delta-Sigma
analog-to-digital
converter,
and
digital
over-temperature detector with an SMBus
TM
interface. The
LM84 senses its own temperature as well as the tempera-
ture of a target IC with a diode junction, such as a Pentium
II processor or a diode connected 2N3904. A diode junction
(semiconductor junction) is required on the target IC's die. A
host can query the LM84 at any time to read the temperature
of this diode as well as the temperature state of the LM84
itself. A T_CRIT_A interrupt output becomes active when the
temperature is greater than a programmable comparator
limit, T_CRIT.
The host can program as well as read back the state of the
T_CRIT register. Three state logic inputs allow two pins
(ADD0, ADD1) to select up to 9 SMBus address locations for
the LM84. The sensor powers up with default thresholds of
127C for T_CRIT.
Features
n
Directly senses die temperature of remote ICs
n
Senses temperature of remote diodes
n
SMBus compatible interface, supports SMBus Timeout
n
Register readback capability
n
7 bit plus sign temperature data format
n
2 address select lines enable 9 LM84s to be connected
to a single bus
Key Specifications
j
Supply Voltage
3.0V - 3.6V
j
Supply Current
1 mA (max)
j
Local Temperature Accuracy
1.0C (typ)
j
Remote Diode Temperature Accuracy
+60C to +100C
3C (max)
0C to +125C
5C (max)
Applications
n
System Thermal Management
n
Personal Computers
n
Electronic Test Equipment
n
Office Electronics
n
HVAC
Simplified Block Diagram
SMBus
TM
is a trademark of the Intel Corporation.
Pentium
II processor is a registered trademark of the Intel Corporation.
I2C
is a registered trademark of the Philips Corporation.
DS100961-1
# Indicates Active Low ("NOT")
July 2000
LM84
Diode
Input
Digital
T
emperature
Sensor
with
T
wo-W
ire
Interface
2001 National Semiconductor Corporation
DS100961
www.national.com
Connection Diagram
Ordering Information
Order
Number
NS
Package
Number
Transport
Media
SMBus
Revision
Level
Noise Filter
on SMBCLK
LM84BIMQA
MQA16A
(QSOP-16)
95 Units in
Rail
1.1
20MHz
LM84BIMQAX
MQA16A
(QSOP-16)
2500 Units on
Tape and
Reel
1.1
20MHz
LM84CIMQA
MQA16A
(QSOP-16)
95 Units in
Rail
1.0
Not Available
LM84CIMQAX
MQA16A
(QSOP-16)
2500 Units on
Tape and
Reel
1.0
Not Available
Typical Application
QSOP-16
DS100961-2
TOP VIEW
DS100961-3
LM84
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2
Pin Descriptions
Label
Pin #
Function
Typical Connection
NC
1, 5, 9,
13, 16
Manufacturing test pins.
Left floating. PC board traces may be routed
through the pads for these pins. Although, the
components that drive these traces should share
the same supply as the LM84 so that the Absolute
Maximum Voltage at any Pin rating is not violated.
V
CC
2
Positive Supply Voltage
Input
DC Voltage from 3.0V to 3.6V
D+
3
Diode Current Source
To Diode Anode. Connected to remote discrete
diode or to the diode on the external IC whose die
temperature is being sensed.
D-
4
Diode Return Current
Sink
To Diode Cathode. Must be grounded when not
used.
ADD0ADD1
10, 6
User-Set SMBus (I
2
C)
Address Inputs
Ground (Low, "0"), V
CC
(High, "1") or open
("TRI-LEVEL")
GND
7, 8
Power Supply Ground
Ground
T_CRIT_A
11
Critical Temperature
Alarm, open-drain output
Pull Up Resistor, Controller Interrupt Line or
System Shutdown
SMBData
12
SMBus (I
2
C) Serial
Bi-Directional Data Line,
open-drain output
From and to Controller, Pull Up Resistor
SMBCLK
14
SMBus (I
2
C) Clock Input
From Controller
NC
15
No Connection
Left floating. PC board traces may be routed
through the pads for this pin.
LM84
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Absolute Maximum Ratings
(Note 1)
Supply Voltage
-0.3V to 6.0V
Voltage at Any Pin:
NC (Pins 1,5,9), ADD0, ADD1, D
+
-0.3V to
(V
CC
+ 0.3V)
All other pins (except D-)
-0.3V to 6.0V
D- Input Current
1 mA
Input Current at All Other Pins (Note
2)
5 mA
Package Input Current (Note 2)
20 mA
SMBData, T_CRIT_A Output Sink
Current
10 mA
Output Voltage
6.0V
Storage Temperature
-65C to +150C
Soldering Information, Lead Temperature
QSOP Package (Note 3)
Vapor Phase (60 seconds)
215C
Infrared (15 seconds)
220C
ESD Susceptibility (Note 4)
Human Body Model
2500V
Machine Model
250V
Operating Ratings
(Note 1) and (Note 5)
Specified Temperature Range
T
MIN
to T
MAX
LM84
0C to +125C
Supply Voltage Range (V
CC
)
+3.0V to +3.6V
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for V
CC
=+3.0 Vdc 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.
Parameter
Conditions
Typical
Limits
Units
(Note 6)
(Note 7)
(Limit)
Local Temperature Error (Note 8)
1
C
Remote Temperature Error using
Pentium Diode (Note 8) and (Note
9)
+60C
T
A
+100C,
V
CC
= 3.3 Vdc
3
C (max)
0C
T
A
+125C,
V
CC
= 3.3 Vdc
5
C (max)
Remote Temperature Error using
Diode Connected 2N3904 (Note 8)
and (Note 9)
+60C
T
A
+100C,
V
CC
= 3.3 Vdc
+1, -5
C (max)
0C
T
A
+125C,
V
CC
= 3.3 Vdc
+3, -7
C (max)
Resolution
8
Bits
1
C
Temperature Conversion Time
(Note 11)
120
145
ms
Quiescent Current (Note 10)
SMBus (I
2
C Inactive)
0.500
1
mA (max)
D- Source Voltage
0.7
V
Diode Source Current
(D+ - D-)=+ 0.65V; high
level
160
A (max)
50
A (min)
Low level
16
A (max)
5
A (min)
T_CRIT_A Output Saturation
Voltage
I
OUT
= 3.0 mA
0.4
V (max)
Power-On Reset Threshold
On V
CC
input, falling
edge
2.2
1.2
V (max)
V (min)
Local and Remote T_CRIT Default
Temperature
(Note 12)
+127
C
LM84
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Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS
Unless otherwise noted, these specifications apply for V
CC
=+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
LM84B
LM84C
Units
(Note 6)
Limits
(Note 7)
Limits
(Note 7)
(Limit)
SMBData, SMBCLK
V
IN(1)
Logical "1" Input Voltage
2.1
1.4
V (min)
V
IN(0)
Logical "0"Input Voltage
0.8
0.6
V (max)
I
IN(1)
Logical "1" Input Current
V
IN
= V
CC
0.005
1.0
1.0
A (max)
I
IN(0)
Logical "0" Input Current
V
IN
= 0V
-0.005
-1.0
-1.0
A (max)
ADD0, ADD1
V
IN(1)
Logical "1" Input Voltage
V
CC
1.6
1.6
V (min)
V
IN(0)
Logical "0"Input Voltage
GND
0.5
0.5
V (max)
I
IN(1)
Logical "1" Input Current
V
IN
= V
CC
50
600
600
A (max)
I
IN(0)
Logical "0" Input Current
V
IN
= 0V
50
600
600
A (max)
ALL DIGITAL INPUTS
C
IN
Input Capacitance
20
pF
ALL DIGITAL OUTPUTS
I
OH
High Level Output Current
V
OH
= V
CC
100
100
A (max)
V
OL
SMBus Low Level Output
Voltage
I
OL
= 3 mA
I
OL
= 6 mA
0.4
0.6
0.4
0.6
V (max)
LM84
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