|
|
PDF LM84CIMQAX Data sheet ( Hoja de datos )
| Número de pieza | LM84CIMQAX | |
| Descripción | Diode Input Digital Temperature Sensor with Two-Wire Interface | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LM84CIMQAX (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
June 1999
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™ 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 it-
self. 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
127˚C 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
n Supply Voltage
n Supply Current
n Local Temperature Accuracy
n Remote Diode Temperature Accuracy
+60˚C to +100˚C
0˚C to +125˚C
3.0V - 3.6V
1 mA (max)
±1.0˚C (typ)
±3˚C (max)
±5˚C (max)
Applications
n System Thermal Management
n Personal Computers
n Electronic Test Equipment
n Office Electronics
n HVAC
Simplified Block Diagram
# Indicates Active Low (”NOT“)
SMBus™ is a trademark of the Intel Corporation.
Pentium II® is a registered trademark of the Intel Corporation.
I2C® is a registered trademark of the Philips Corporation.
© 1999 National Semiconductor Corporation DS100961
DS100961-1
www.national.com
1 page  
Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS
Unless otherwise noted, these specifications apply for VCC=+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)
SMBData, SMBCLK
VIN(1)
VIN(0)
IIN(1)
IIN(0)
ADD0, ADD1
Logical “1” Input Voltage
Logical “0”Input Voltage
Logical “1” Input Current
Logical “0” Input Current
VIN = VCC
VIN = 0V
0.005
−0.005
1.4 V (min)
0.6 V (max)
1.0 µA (max)
−1.0
µA (max)
VIN(1)
Logical “1” Input Voltage
VIN(0)
Logical “0”Input Voltage
IIN(1)
Logical “1” Input Current
IIN(0)
Logical “0” Input Current
ALL DIGITAL INPUTS
VIN = VCC
VIN = 0V
VCC
GND
50
50
1.6 V (min)
0.5 V (max)
600 µA (max)
600 µA (max)
CIN Input Capacitance
ALL DIGITAL OUTPUTS
20 pF
IOH
High Level Output Current
VOH = VCC
VOL
SMBus Low Level Output
IOL = 3 mA
Voltage
IOL = 6 mA
100 µA (max)
0.4 V (max)
0.6
5 www.national.com
5 Page 
1.0 Functional Description (Continued)
1.7 COMMUNICATING with the LM84
There are 10 data registers in the LM84, selected by the
Command Register. At power-up the Command Register is
set to “00”, the location for the Read Local Temperature Reg-
ister. The Command Register latches whatever the last loca-
tion it was set to. Reading the Status Register resets
T_CRIT_A. All registers are predefined as read only or write
only. Read and write registers with the same function contain
mirrored data.
A Write to the LM84 will always include the address byte and
the command byte. A write to any register requires one data
byte.
Reading the LM84 can take place either of two ways:
1. If the location latched in the Command Register is cor-
rect (most of the time it is expected that the Command
Register will point to one of the Read Temperature Reg-
isters because that will be the data most frequently read
from the LM84), the read can simply consist of an ad-
dress byte, followed by retrieving the data byte.
2. If the Command Register needs to be set, then an ad-
dress byte, command byte, repeat start, and another ad-
dress byte will accomplish a read.
The data byte has the most significant bit first. At the end of
a read, the LM84 can accept either Acknowledge or No Ac-
knowledge from the Master (No Acknowledge is typically
used as a signal for the slave that the Master has read its
last byte).
DS100961-9
1.7.1 SMBus TIMEOUT
The LM84 SMBus interface circuitry will be reset to the SM-
Bus idle state if the SMBData or SMBCLK lines are held low
for more than 40 ms. The LM84 may or may not reset the
state SMBData or SMBCLK if either of these lines are held
low between 25 ms and 40 ms. Holding SMBData or SMB-
CLK low for less than or equal to 25 ms will not reset the in-
terface circuitry. The LM84 has a built-in internal timer to
guarantee that the interface is reset if the SMBData line were
to get stuck low. This can commonly occur when the master
is reset while the slave is transmitting low. This enhance-
ment to the SMBus TIMEOUT specification ensures error
free performance even in remote systems where complete
power supply shutdown, for reset, is a nuisance. This would
have to occur since many cost effective temperature sensors
such as the LM84 do not have a pin dedicated for reset.
11 www.national.com
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LM84CIMQAX.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LM84CIMQA | Diode Input Digital Temperature Sensor with Two-Wire Interface | National Semiconductor |
| LM84CIMQAX | Diode Input Digital Temperature Sensor with Two-Wire Interface | National Semiconductor |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |