Features
| • | 2-wire, SMBus 2.0 compliant, serial digital interface |
| • | 8-bit [Sigma][Delta] ADC |
| • | Monitors VCCP, 2.5V, 3.3 VSBY, 5.0V, and 12V motherboard/processor supplies |
| • | Monitors 2 remote thermal diodes |
| • | Programmable autonomous fan control based on temperature readings |
| • | 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 |
Description The LM85, hardware monitor, has a two wire digital interface compatible with SMBus 2.0. Using an 8-bit [Sigma][Delta] 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.
Key Specification
Voltage Measurement Accuracy |
±2% FS (max) |
Resolution |
8-bits, 1°C |
Temperature Sensor Accuracy |
±3°C (max) |
Temperature Range |
|
LM85 Operational |
0°C to +85°C |
Remote Temp Accuracy |
0°C to +125°C |
Power Supply Voltage |
+3.0V to +3.6V |
Power Supply Current |
0.53 mA |
Applications
- Desktop PC
- Microprocessor based equipment (e.g. Base-stations, Routers, ATMs, Point of Sales)
Information on the differences between the LM85BIMQ and LM85CIMQ can be found in Section 6.0. It is highly recommended that all new designs use the LM85BIMQ.
| Date | Revision |
|---|
| 8/2002 | Added LM85BIMQ functional differences and specifications. |
| 3/2003 | Updated Register 74h, Tachometer Monitor Mode description. |
| | |
|
Also Recommended
| LM96000▲ | Functional Equivalent That Supports 22.5kHz PWM Fan Drive |
| LM96194▲ | PI Fan Control With TruTherm(TM) Technology |
|
|
