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NATIONAL SEMICONDUCTOR'S NEW DIAGNOSTIC IC MONITORS KEY ANALOG AND DIGITAL FUNCTIONS FOR MICROPROCESSOR-BASED SYSTEMS
"In today's cost-sensitive personal systems market, total cost of system ownership is a critical factor in the purchase of new high-powered microprocessor systems," said Patricia Smith, National's temperature sensor marketing manager. "By enabling desktop diagnostics and highlighting the need for preventive maintenance, the LM78 offers the board manufacturers the perfect tool for enabling long-term system reliability at a lower cost to the user." National's device gives information technology managers the capability to set "hazard warning limits" via watchdog registers for most key analog functions within the PC/server environment, enabling the generation of interrupts based on the performance of system functions.
Key features of the LM78 include:
- +/3°C temperature accuracy
- User-programmable watchdog limits register for Tos (over-temperature) and Thyst (hysteresis)
- Seven voltage monitoring analog inputs (0-4.096V Full Scale Range)
- Associated watchdog registers for each voltage input (high and low)
- Three fan inputs including two user-programmable inputs for speeds ranging from 1100 rpm to 8800 rpm; one for fixed inputs from a standard 4400 rpm tach output fan
- Active-high chassis security input for detection of intrusion
- Board temperature interrupt input (BTI#), for use with thermostat output temp sensors (such as National's LM75 or LM56) which may be located in strategic positions throughout the system.
The highly integrated LM78 includes an 8-bit Delta-Sigma A/D converter with 7-input MUX for high noise immunity in microprocessor environments. Also included are inverting op amps to accommodate measurement of negative power supplies. An on-board 32-bit POST RAM (Power-On, Self-Test RAM) allows the LM78 to be among the first devices on the mother board to waken and record the performance of other system parts during system boot-up.
National will be offering an application board to facilitate quick, easy hook-up to a power supply and evaluation of its output characteristics. The board is designed to slot into an ISA bus, or to plug into the parallel printer port for communication via the I2C interface.
Price & Availability
The LM78 is priced at $5.50 in 1,000-unit quantities in a 44-lead PQFP. For data sheets and user information on the LM78 or other National products, visit our World Wide Web site at http://www.national.com.
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