Datasheet

LM82

SNIS113D –JANUARY 2000–REVISED MARCH 2013

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Address Select Pin State LM82 SMBus Slave Address

ADD0 ADD1 A6:A0 binary

0 1 001 1010

TRI-LEVEL 0 010 1001

TRI-LEVEL TRI-LEVEL 010 1010

TRI-LEVEL 1 010 1011

1 0 100 1100

1 TRI-LEVEL 100 1101

1 1 100 1110

The LM82 latches the state of the address select pins during the first read or write on the SMBus. Changing the

state of the address select pins after the first read or write to any device on the SMBus will not change the slave

address of the LM82.

TEMPERATURE DATA FORMAT

Temperature data can be read from the Local and Remote Temperature, T_CRIT, and HIGH setpoint registers;

and written to the T_CRIT and HIGH setpoint registers. Temperature data is represented by an 8-bit, two's

complement byte with an LSB (Least Significant Bit) equal to 1°C:

Temperature Digital Output

Binary Hex

+125°C 0111 1101 7Dh

+25°C 0001 1001 19h

+1°C 0000 0001 01h

0°C 0000 0000 00h

−1°C 1111 1111 FFh

−25°C 1110 0111 E7h

−55°C 1100 1001 C9h

OPEN-DRAIN OUTPUTS

The SMBData, INT and T_CRIT_A outputs are open-drain outputs and do not have internal pull-ups. A “high”

level will not be observed on these pins until pull-up current is provided from 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. This will minimize any internal temperature reading errors due to internal heating

of the LM82. The maximum resistance of the pull up, based on LM82 specification for High Level Output Current,

to provide a 2.1V high level, is 30kΩ. Care should be taken in a noisy system because a high impedance pull-up

will be more likely to couple noise into the signal line.

DIODE FAULT DETECTION

Before each external conversion the LM82 goes through an external diode fault detection sequence. If D+ input

is shorted to V

or floating then the temperature reading will be +127 °C, and the OPEN bit in the Status

temperature reading will be 0 °C and its OPEN bit in the Status Register will not be set.

Product Folder Links: LM82