LM82

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SNIS113D – JANUARY 2000 – REVISED MARCH 2013

Figure 10. T_CRIT_A output related circuitry logic diagram

Located in the Configuration Register are the mask bits for each temperature reading, see CONFIGURATION

REGISTER . When a mask bit is set, its corresponding status flag will not propagate to the T_CRIT_A output, but

will still be set in the Status Registers. Configuration register bits D5 and D3, labled “Remote T_CRIT_A mask”

must be set high before the T_CRIT setpoint is lowered in order for the T_CRIT_A output to function properly.

Setting all four mask bits or programming the T_CRIT setpoint to 127°C will disable the T_CRIT_A output.

POWER ON RESET DEFAULT STATES

LM82 always powers up to these known default states:

1. Command Register set to 00h

2. Local Temperature set to 0°C

3. Remote Temperature set to 0°C until the LM82 senses a diode present between the D+ and D

− input pins.

4. Status Register set to 00h.

5. Configuration Register set to 00h; INT enabled and all T_CRIT setpoints enabled to activate T_CRIT_A.

6. Local and Remote T_CRIT set to 127°C

SMBus INTERFACE

The LM82 operates as a slave on the SMBus, so the SMBCLK line is an input (no clock is generated by the

LM82) and the SMBData line is bi-directional. According to SMBus specifications, the LM82 has a 7-bit slave

address. Bit 4 (A3) of the slave address is hard wired inside the LM82 to a 1. The remainder of the address bits

are controlled by the state of the address select pins ADD1 and ADD0, and are set by connecting these pins to

Therefore, the complete slave address is:

A6

A5

A4

1

A2

A1

A0

MSB

LSB

and is selected as follows:

Address Select Pin State

LM82 SMBus Slave Address

ADD0

ADD1

A6:A0 binary

0

0

001 1000

0

TRI-LEVEL

001 1001

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