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 127°C for T_CRIT.
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