LM85
LM85 is Hardware Monitor manufactured by National Semiconductor.
Description
The LM85, hardware monitor, has a two wire digital interface patible 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 m A
Features n 2-wire, SMBus 2.0 pliant, 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 n Programmable autonomous fan control based on temperature readings
Applications n Desktop PC n Microprocessor based equipment (e.g. Base-stations, Routers, ATMs, Point of Sales)
Block Diagram
© 2003 National Semiconductor Corporation
DS200353
.national.
Connection Diagram
24 Pin QSOP
NS Package MQA24 Top View LM85BIMQ or LM85CIMQ (55 units per rail), or LM85BIMQX or LM85CIMQX (2500 units per tape and reel) Information on the differences between the LM85BIMQ and LM85CIMQ can be found in Section 6.0. It is highly remended that all new designs use the LM85BIMQ.
Pin Descriptions
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