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Features
Temperature sensing
5 positive voltage inputs
2 op amps for negative voltage monitoring
3 fan speed monitoring inputs
Input for additional temperature sensors
Chassis Intrusion Detector input
WATCHDOG comparison of all monitored values
POST code storage RAM
ISA and I2C™ Serial Bus interfaces
Description The LM79 is a highly integrated Data Acquisition system for hardware monitoring of servers, Personal Computers, or virtually any microprocessor based system. In a PC, the LM79 can be used to monitor power supply voltages, temperatures, and fan speeds. Actual values for these inputs can be read at any time, and programmable WATCHDOG limits in the LM79 activate a fully programmable and maskable interrupt system with two outputs.
The LM79 has an on-chip temperature sensor, 5 positive analog inputs, two inverting inputs (for monitoring negative voltages), and an 8-bit ADC. An input is provided for the overtemperature outputs of additional temperature sensors and this is linked to the interrupt system. The LM79 provides inputs for three fan tachometer outputs. Additional inputs are provided for Chassis Intrusion detection circuits, 5 VID monitor inputs, and chainable interrupt. The LM79 provides both ISA and Serial Bus interfaces. A 32-byte auto-increment RAM is provided for POST (Power On Self Test) code storage.
Compared to the LM78, the LM79 has the following differences:
- an additional VID input pin
- an additional register for device identification
- open drain Power Switch Bypass# Output
Key Specification
| Voltage monitoring accuracy | | ±1% (max) |
| Temperature Accuracy -10°C to +100°C | | ±3°C (max) |
| Supply Voltage | | 5V |
| Supply Current | Operating: | 1 mA typ |
| | Shutdown: | 10 µA typ |
| ADC Resolution | | 8 Bits |
Applications
System Hardware Monitoring for Servers and PCs
Office Electronics
Electronic Test Equipment and Instrumentation
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Also Recommended
| LM80 | Max Output 0-2.56V (Next Generation) |
| LM81 | Additional DAC Output For Fan Speed Control |
| LM87 | Additional 2 Sets Remote Diode Sensing |
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