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Features
Directly senses die temperature of remote ICs
Senses temperature of remote diodes
SMBus compatible interface, supports SMBus Timeout
Register readback capability
7 bit plus sign temperature data format
2 address select lines enable 9 LM91s to be connected to a single bus
Description The LM91 is a remote diode temperature sensor, Delta-Sigma analog-to-digital converter, and digital over-temperature detector with an SMBus™ interface. The LM91 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 LM91 at any time to read the temperature of this diode as well as the temperature state of the LM91 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. Power up default values for T_CRIT are as shown in the ordering information table. Three state logic inputs allow two pins (ADD0, ADD1) to select up to 9 SMBus address locations for the LM91.
Key Specification
| Supply Voltage | 3.0V - 3.6V |
| Supply Current | 1 mA (max) |
| Local Temperature Accuracy | ±1.0°C (typ) |
| Remote Diode Temperature Accuracy | |
| +60°C to +100°C | ±4°C (max) |
| 0°C to +125°C | ±6°C (max) |
Applications
System Thermal Management
Personal Computers
Electronic Test Equipment
Office Electronics
HVAC
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