Datasheet

LM95233

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SNIS145E –AUGUST 2006–REVISED MARCH 2013

Local Temperature data is only represented by an 11-bit, two's complement, word with an LSb equal to 0.125°C.

Table 5. 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

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 temperature reading

errors due to internal heating of the LM95233. The maximum resistance of the pull-up to provide a 2.1V high

level, based on LM95233 specification for High Level Output Current with the supply voltage at 3.0V, is 82 kΩ

(5%) or 88.7 kΩ (1%).

TCRIT1, TCRIT2, AND TCRIT3 OUTPUTS

The LM95233'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 general, 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 LM95233. The maximum

resistance of the pull-up to provide a 2.1V high level, based on LM95233 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 ensure 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 resistance of

77.8°C/W will cause the LM95233's junction temperature 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 LM95233 is enclosed in

has stable and controlled air flow over the LM95233, as airflow can cause the thermal resistance to change

dramatically.

TCRIT LIMITS AND TCRIT OUTPUTS

Figure 13 describes a simplified diagram of the temperature comparison and status register logic. Figure 14

describes a simplified logic diagram of the circuitry associated with the status registers, mask registers and the

TCRIT output pins.

Product Folder Links: LM95233