Features: ` 2-wire, SMBus 2.0 compliant, serial digital interface
` 8-bit ∆ 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 modeApplication·Desktop PC
·Microprocessor based equipment (e.g. Base-stations, Routers, ATMs, Point of Sales)
SpecificationsSupply Voltage, V+ .................................................................................−0.5V to 6.0V
Voltage on Any Digital Input or ..............................................................−0.5V to 6.0V
Output Pin
Voltage on 12V Analog Input ..................................................................−0.5V to 16V
Voltage on 5V Analog Input .................................................................−0.5V to 6.66V
Voltage on Remote1+, Remote2+, ............................................−0.5V to (V+ + 0.05V)
Current on Remote1−, Remote2− ....................................................................±1 mA
Voltage on Other Analog Inputs ............................................................−0.5V to 6.0V
Input Current on Any Pin (Note 3) ....................................................................±5 mA
Package Input Current (Note 3) .....................................................................±20 mA
Package Dissipation at TA = 25°C ..........................................................See (Note 5)
ESD Susceptibility (Note 4)
Human Body Model ...........................................................................................2500V
Machine Model ....................................................................................................250V
Soldering Temperature, Infrared, ....................................................................235°C
10 seconds (Note 6)
Storage Temperature ...................................................................−65°C to +150°C
| Temp Resolution |
8-bit/1degC |
| Remote Diode Thermal Sensors |
2 |
| TruTherm(TM) Beta Compensation |
No |
| Analog Inputs |
4, V+ |
| ADC Resolution |
8 bits |
| Fan Speed Inputs |
4 |
| Fan Control Output(s) |
3 PWM |
| Fan Control Method |
Linear |
| VID Inputs |
5 |
| Temperature Accuracy (+/-) |
2.5 deg C |
| Temperature Min |
0 deg C |
| Temperature Max |
125 deg C |
| Interface Type |
SMBus |
| Supply Min |
3.0 Volt |
| Supply Max |
3.6 Volt |
| Quiescent Current |
0.53 mA |
| Resolution |
8 bits |
| Temperature Accuracy (+/-) |
1 deg C |
| View Using Catalog |
DescriptionThe 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.
Design Tools
| Title |
Size in Kbytes |
Date |
|
|
|
| SensorEval Software for Thermal Mangement Products |
6 Kbytes |
15-May-2008 |
View |
|
|
If you have trouble printing or viewing PDF file(s), see Printing Problems.
|
Application Notes
| Title |
Size in Kbytes |
Date |
|
| AN-1260: Application Note 1260 Autonomous Fan Control for Processor Systems Using the LM85 |
74 Kbytes |
10-Mar-04 |
Download |
If you have trouble printing or viewing PDF file(s), see Printing Problems.
|
More Application Notes
| Title |
Size in Kbytes |
Date |
|
| AN-1155: Application Note 1155 A Simple Software I2C Routine for the COP8 |
82 Kbytes |
15-May-04 |
Download |
| AN-1262: Application Note 1262 Four-Speed Fan Control Using Simple Remote Diode Temperature Sensor |
70 Kbytes |
1-Oct-02 |
Download |
If you have trouble printing or viewing PDF file(s), see Printing Problems.
|
LM85 Data Sheet
