LM40 Datasheet | National Semiconductor

Description The LM40 is a hardware monitor that measures 3 temperature zones, 5 voltages and has a single-wire interface patible with National Semiconductor’s Sensor Path bus. Sensor Path data is pulse width encoded, thereby allowing the LM40 to be easily connected to many general purpose micro-controllers. Several National Semiconductor Super I/O products include a fully integrated Sensor Path master, that when connected to the LM40 can realize a hardware monitor function that includes limit checking for measured values, autonomous fan speed control and many other functions. The LM40 measures the temperature of its own die as well as two external devices such as a processor thermal diode or a diode connected transistor. The LM40 can resolve temperatures up to 255˚C and down to -256˚C. The operating temperature range of the LM40 is 0˚C to +125˚C. Using Σ∆ ADC it measures +1.2V, +2.5V, +3.3V, +5V and +12V analog input voltages with internal scaling resistors.The address programming pin allows two LM40s to be placed on one Sensor Path bus. - Internal scaling resistors for all inputs - Monitors +1.2V, +2.5 V, +3.3 V, +5 V and +12 V n Temperature Sensing - 2 remote diode temperature sensor zones - Internal local temperature zone - 0.5 ˚C resolution - Measures temperatures up to 140 ˚C n 14-lead TSSOP package Key Specifications n Voltage Measurement Accuracy n Temperature Sensor Accuracy n Temperature Range: - LM40 junction - Remote Temp Accuracy n Power Supply Voltage n Average Power Supply Current n Conversion Time (all Channels) ± 2 % (max) ± 3 ˚C (max) 0 ˚C to +85 ˚C 0 ˚C to +100 ˚C +3.0 V to +3.6 V 0.5 m A (typ) 29.6ms to 1456ms Applications n Microprocessor based equipment (Motherboards, Video Cards, Base-stations, Routers, ATMs, Point of Sale, …) n Power Supplies Features n Sensor Path Interface - 2 hardware programmable addresses n Voltage Monitoring - 9-bit Σ∆ ADC Typical Application Sensor Path™ is a trademark of National Semiconductor Corporation ©...