The LM84 is a remote diode temperature sensor, Delta-Sigma analog-to-digital converter, and digital
over-temperature detector with an SMBus interface. The LM84 senses its own temperature as well as the temperature of a target IC with a diode junction, such as a Pentium II Processor or a diode connected 2N3904. A diode junction (semiconductor junction) is required on the target IC's die. A host can query the LM84 at any time to read the temperature of this diode as well as the temperature state of the LM84 itself. A T_CRIT_A interrupt output becomes active when the temperature is greater than a programmable comparator limit, T_CRIT. The host can program as well as read back the state of the
T_CRIT register. Three state logic inputs allow two pins (ADD0, ADD1) to select up to 9 SMBus address locations for the LM84. The sensor powers up with default thresholds of 127C for T_CRIT.