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PDF LM95245 Data sheet ( Hoja de datos )
| Número de pieza | LM95245 | |
| Descripción | Precision Remote Diode Digital Temperature Sensor | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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March 13, 2008
LM95245
Precision Remote Diode Digital Temperature Sensor with
TruTherm® BJT Beta Compensation Technology for 45nm
Process
General Description
The LM95245 is an 11-bit digital temperature sensor with a
2-wire System Management Bus (SMBus) interface and
TruTherm technology that can monitor the temperature of a
remote diode as well as its own temperature. The LM95245
can be used to very accurately monitor the temperature of
external devices such as microprocessors. TruTherm tech-
nology allows the LM95245 to precisely monitor thermal
diodes found in 90 nm and smaller geometry processes. The
LM95245 is specifically targeted for Intel processors on 45nm
process. LM95245 reports temperature in two different for-
mats for +127.875°C/-128°C range and 0°C/255°C range.
The LM95245 T_CRIT and OS outputs are asserted when
either unmasked channel exceeds its programmed limit and
can be used to shutdown the system, to turn on the system
fans, or as a microcontroller interrupt function. The current
status of the T_CRIT and OS pins can be read back from the
status registers via the SMBus interface. All limits have a
shared programmable hysteresis register.
The remote temperature channel of the LM95245 has a pro-
grammable digital filter. The LM95245 is targeted for a typical
Intel® processor on a 45 nm, 65 nm or 90nm process, and
has an offset register for maximum flexibility and best accu-
racy.
The LM95245 has a three-level address pin to connect up to
3 devices to the same SMBus master, that is shared with the
OS output. The LM95245 has a programmable conversion
rate register and a standby mode to save power. One con-
version can be triggered in standby mode by writing to the
one-shot register.
Features
■ Remote and Local temperature channels
■ Targeted for Intel 45nm processor diodes
■ Two Formats: −128°C to +127.875°C and
0°C to 255.875°C
■ Digital filter for remote channel
■ Programmable TCRIT and OS thresholds
■ Programmable shared hysteresis register
■ Diode Fault Detection
■ Mask, Offset, and Status Registers
■ SMBus 2.0 compatible interface, supports TIMEOUT
■ Programmable conversion rate for best power
consumption
■ Three-level address pin
■ Standby mode one-shot conversion control
■ Pin-for-pin compatible with the LM95235 and LM86/LM89/
LM99
■ 8-pin MSOP and SOP packages
Key Specifications
■ Supply Voltage
■ Supply Current, Conv. Rate = 1 Hz
■ Remote Diode Temperature Accuracy
TA = 25°C to 85°C; TD = 50°C to 105°C
TA = 25°C to 85°C; TD = 40°C to 125°C
■ Local Temperature Accuracy
TA = 25°C to 100°C
■ Conversion Rate, Both Channels
3.0 V to 3.6 V
350 µA (typ)
±0.75°C (max)
±1.5°C (max)
±2.0°C (max)
16 to 0.4 Hz
Applications
■ Processor/Computer System Thermal Management
(e.g. Laptops, Desktops, Workstations, Servers)
■ Electronic Test Equipment
■ Office Electronics
Connection Diagram
MSOP-8 and SOP-8
TruTherm® is a registered trademark of National Semiconductor Corporation.
Intel® is a registered trademark of Intel Corporation.
Pentium® is a registered trademark of Intel Corporation.
© 2008 National Semiconductor Corporation 300151
TOP VIEW
30015102
www.national.com
1 page  
Parameter
Conditions
T_CRIT Pin Temperature
Threshold
OS Pin Temperature Threshold
Default
Default
Typical
(Note 6)
+110
+85
LM95245
CIMM,
LM95245
CIM
Limits
(Note 7)
Units
°C
°C
Logic Electrical Characteristics
Digital DC Characteristics
Unless otherwise noted, these specifications apply for VDD= +3.0 Vdc 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)
SMBDAT, SMBCLK INPUTS
VIN(1)
Logical “1” Input Voltage
VIN(0)
Logical “0” Input Voltage
VIN(HYST)
SMBDAT and SMBCLK Digital Input Hysteresis
IIN(1)
Logical “1” Input Current
IIN(0)
Logical “0” Input Current
CIN Input Capacitance
A0 DIGITAL INPUT
2.1 V (min)
0.8 V (max)
400 mV
VIN = VDD
−0.005
−10
µA (max)
VIN = 0 V
0.005
+10 µA (max)
5 pF
VIH Input High Voltage
VIM Input Middle Voltage
VIL Input Low Voltage
IIN(1)
Logical “1” Input Current
IIN(0)
Logical “0” Input Current
CIN Input Capacitance
SMBDAT, T_CRIT, OS DIGITAL OUTPUTS
VIN = VDD
VIN = 0 V
−0.005
0.005
5
0.90 × VDD
0.57 × VDD
0.43 × VDD
0.10 × VDD
−10
+10
V (min)
V (max)
V (min)
V (max)
µA (max)
µA (max)
pF
IOH
VOL(T_CRIT, OS)
VOL(SMBDAT)
COUT
High Level Output Leakage Current
T_CRIT, OS Low Level Output Voltage
SMBDAT Low Level Output Voltage
Digital Output Capacitance
VOUT = VDD
IOL = 6 mA
IOL = 4 mA
IOL = 6 mA
5
10 µA (max)
0.4 V (max)
0.4 V (max)
0.6 V (max)
pF
5 www.national.com
5 Page 
Figure 3 shows the filter in use in a typical Intel processor on
a 45/65/90 nm process system. Note that the two curves have
been purposely offset for clarity. Inserting the filter does not
induce an offset as shown.
30015127
FIGURE 3. Digital Filter Response in a typical Intel
processor on a 45nm, 65 nm or 90 nm process. The filter
curves were purposely offset for clarity.
1.5 TEMPERATURE DATA FORMAT
Temperature data can only be read from the Local and Re-
mote Temperature registers.
Remote temperature data with the digital filter off is repre-
sented by an 10-bit plus sign, two's complement word and 11-
bit unsigned binary word with an LSb (Least Significant Bit)
equal to 0.125°C. The data format is a left justified 16-bit word
available in two 8-bit registers. Unused bits report "0".
Remote temperature data with the digital filter on is repre-
sented by a 12-bit plus sign, two's complement word and 13-
bit unsigned binary word with an LSb (Least Significant Bit)
equal to 0.03125°C (1/32°C). The data format is a left justified
16-bit word available in two 8-bit registers. Unused bits report
"0".
11-bit, 2's complement (10-bit plus sign)
Temperature
Digital Output
Binary
Hex
+125°C
0111 1101 0000 0000
7D00h
+25°C
0001 1001 0000 0000
1900h
+1°C
0000 0001 0000 0000
0100h
+0.125°C
0000 0000 0010 0000
0020h
0°C
0000 0000 0000 0000
0000h
−0.125°C
1111 1111 1110 0000
FFE0h
−1°C
1111 1111 0000 0000
FF00h
−25°C
1110 0111 0000 0000
E700h
−55°C
1100 1001 0000 0000
C900h
11-bit, unsigned binary
Temperature
Digital Output
Binary
Hex
+255.875°C 1111 1111 1110 0000
FFE0h
+255°C
1111 1111 0000 0000
FF00h
+201°C
1100 1001 0000 0000
C900h
+125°C
0111 1101 0000 0000
7D00h
+25°C
0001 1001 0000 0000
1900h
+1°C
0000 0001 0000 0000
0100h
+0.125°C
0000 0000 0010 0000
0020h
0°C
0000 0000 0000 0000
0000h
13-bit, 2's complement (12-bit plus sign)
Temperature
Digital Output
Binary
Hex
+125°C
0111 1101 0000 0000
7D00h
+25°C
0001 1001 0000 0000
1900h
+1°C
0000 0001 0000 0000
0100h
+0.03125°C 0000 0000 0000 1000
0008h
0°C
0000 0000 0000 0000
0000h
−0.03125°C 1111 1111 1111 1000
FFF8h
−1°C
1111 1111 0000 0000
FF00h
−25°C
1110 0111 0000 0000
E700h
−55°C
1100 1001 0000 0000
C900h
13-bit, unsigned binary
Temperature
Digital Output
Binary
Hex
+255.875°C 1111 1111 1110 0000
FFE0h
+255°C
1111 1111 0000 0000
FF00h
+201°C
1100 1001 0000 0000
C900h
+125°C
0111 1101 0000 0000
7D00h
+25°C
0001 1001 0000 0000
1900h
+1°C
0000 0001 0000 0000
0100h
+0.03125°C 0000 0000 0000 1000
0008h
0°C
0000 0000 0000 0000
0000h
Local Temperature data is represented by a 10-bit plus sign,
two's complement word with an LSb (Least Significant Bit)
equal to 0.125°C. The data format is a left justified 16-bit word
available in two 8-bit registers. Unused bits will always report
"0". Local temperature readings greater than +127.875°C are
clamped to +127.875°C, they will not roll-over to negative
temperature readings.
11 www.national.com
11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet LM95245.PDF ] | |
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