LM95234_07 NSC [National Semiconductor], LM95234_07 Datasheet - Page 13

• Manufacturer Part Number: LM95234_07
• Description: Quad Remote Diode and Local Temperature Sensor with SMBus Interface and TruTherm Technology
• Manufacturer: NSC [National Semiconductor]

When the digital filter is enabled on Remote 1 and 2 channels
temperature data is represented by a 13-bit unsigned binary
or 12-bit plus sign (two's complement) word with an LSb equal
to 0.03125°C.
Temperature
Temperature
Temperature
Temperature
+255.875°C
+0.03125°C
−0.03125°C
+255.875°C
+0.03125°C
+0.125°C
−0.125°C
+0.125°C
+255°C
+201°C
+125°C
+125°C
+255°C
+201°C
+125°C
−25°C
−55°C
+25°C
+25°C
−25°C
−55°C
+25°C
+1°C
−1°C
+1°C
+1°C
−1°C
+1°C
0°C
0°C
0°C
0°C
13-bit, 2's Complement (12-bit plus sign)
11-bit, Unsigned Binary
13-bit, Unsigned Binary
0000 0001 0000 0000
0000 0000 0010 0000
0000 0000 0000 0000
1111 1111 1110 0000
1111 1111 0000 0000
1110 0111 0000 0000
1100 1001 0000 0000
1111 1111 1110 0000
1111 1111 0000 0000
1100 1001 0000 0000
0111 1101 0000 0000
0001 1001 0000 0000
0000 0001 0000 0000
0000 0000 0010 0000
0000 0000 0000 0000
0111 1101 0000 0000
0001 1001 0000 0000
0000 0001 0000 0000
0000 0000 0000 1000
0000 0000 0000 0000
1111 1111 1111 1000
1111 1111 0000 0000
1110 0111 0000 0000
1100 1001 0000 0000
1111 1111 1110 0000
1111 1111 0000 0000
1100 1001 0000 0000
0111 1101 0000 0000
0001 1001 0000 0000
0000 0001 0000 0000
0000 0000 0000 1000
0000 0000 0000 0000
Binary
Binary
Binary
Binary
Digital Output
Digital Output
Digital Output
Digital Output
FFE0h
C900h
FFE0h
C900h
7D00h
7D00h
FFF8h
C900h
FFE0h
C900h
7D00h
0100h
0020h
0000h
FF00h
E700h
FF00h
1900h
0100h
0020h
0000h
1900h
0100h
0008h
0000h
FF00h
E700h
FF00h
1900h
0100h
0008h
0000h
Hex
Hex
Hex
Hex
13
Local Temperature data is only represented by an 11-bit,
two's complement, word with an LSb equal to 0.125°C.
1.7 SMBDAT OPEN-DRAIN OUTPUT
The SMBDAT output is an open-drain output and does not
have internal pull-ups. A “high” level will not be observed on
this pin until pull-up current is provided by 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 without effecting the
SMBus desired data rate. This will minimize any internal tem-
perature reading errors due to internal heating of the
LM95234. The maximum resistance of the pull-up to provide
a 2.1V high level, based on LM95234 specification for High
Level Output Current with the supply voltage at 3.0V, is 82
kΩ (5%) or 88.7 kΩ (1%).
1.8 TCRIT1, TCRIT2, and TCRIT3 OUTPUTS
The LM95234's TCRIT pins are active-low open-drain outputs
and do not include internal pull-up resistors. A “high” level will
not be observed on these pins until pull-up current is provided
by some external source, typically a pull-up resistor. Choice
of resistor value depends on many system factors but, in gen-
eral, the pull-up resistor should be as large as possible without
effecting the performance of the device receiving the signal.
This will minimize any internal temperature reading errors due
to internal heating of the LM95234. The maximum resistance
of the pull-up to provide a 2.1V high level, based on LM95234
specification for High Level Output Current with the supply
voltage at 3.0V, is 82 kΩ (5%) or 88.7 kΩ (1%). The three
TCRIT pins can each sink 6 mA of current and still guarantee
a "Logic Low" output voltage of 0.4V. If all three pins are set
at maximum current this will cause a power dissipation of 7.2
mW. This power dissipation combined with a thermal resis-
tance of 77.8°C/W will cause the LM95234's junction temper-
ature to rise approximately 0.6°C and thus cause the Local
temperature reading to shift. This can only be cancelled out if
the environment that the LM95234 is enclosed in has stable
and controlled air flow over the LM95234, as airflow can
cause the thermal resistance to change dramatically.
1.9 Tcrit LIMITS AND TCRIT OUTPUTS
Figure 5 describes a simplified diagram of the temperature
comparison and status register logic. Figure 6 describes a
simplified logic diagram of the circuitry associated with the
status registers, mask registers and the TCRIT output pins.
Temperature
+0.125°C
−0.125°C
+125°C
+25°C
−25°C
−55°C
+1°C
−1°C
0°C
11-bit, 2's Complement (10-bit plus sign)
0111 1101 0000 0000
0001 1001 0000 0000
0000 0001 0000 0000
0000 0000 0010 0000
0000 0000 0000 0000
1111 1111 1110 0000
1111 1111 0000 0000
1110 0111 0000 0000
1100 1001 0000 0000
Binary
Digital Output
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7D00h
FFE0h
C900h
1900h
0100h
0020h
0000h
FF00h
E700h
Hex