LM85

LM85 Hardware Monitor with Integrated Fan Control March 2003 LM85 Hardware Monitor with Integrated Fan Control General Description The LM85, hardware monitor, has a two wire digital interface compatible with SMBus 2.0. Using an 8-bit Σ∆ ADC, the LM85 measures: – the temperature of two remote diode connected transistors as well as its own die – the VCCP, 2.5V, 3.3VSBY, 5.0V, and 12V supplies (internal scaling resistors). To set fan speed, the LM85 has three PWM outputs that are each controlled by one of three temperature zones. The LM85 includes a digital filter that can be invoked to smooth temperature readings for better control of fan speed. The LM85 has four tachometer inputs to measure fan speed. Limit and status registers for all measured values are included. n n n n n n n Noise filtering of temperature reading for fan control 1.0˚C digital temperature sensor resolution 3 PWM fan speed control outputs 4 fan tachometer inputs Monitors 5 VID control lines 24-pin QSOP package XOR-tree test mode Key Specifications Voltage Measurement Accuracy Resolution Temperature Sensor Accuracy Temperature Range — LM85 Operational — Remote Temp Accuracy n Power Supply Voltage n Power Supply Current n n n n ± 2% FS (max) 8-bits, 1˚C ± 3˚C (max) 0˚C to +85˚C 0˚C to +125˚C +3.0V to +3.6V 0.53 mA Features n 2-wire, SMBus 2.0 compliant, serial digital interface n 8-bit Σ∆ ADC n Monitors VCCP, 2.5V, 3.3 VSBY, 5.0V, and 12V motherboard/processor supplies n Monitors 2 remote thermal diodes ...