Datasheet

LM95234

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SNIS136D –AUGUST 2006–REVISED MARCH 2013

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 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%).

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 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 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 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 LM95234'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 LM95234 is enclosed in

has stable and controlled air flow over the LM95234, as airflow can cause the thermal resistance to change

dramatically.

Tcrit LIMITS AND TCRIT OUTPUTS

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

for the TCRIT1, TCRIT2, and TCRIT3 outputs describes a simplified logic diagram of the circuitry associated with

the status registers, mask registers and the TCRIT output pins.

Product Folder Links: LM95234