blob: a1790401fddee6bed131867878257b2004a91989 [file] [log] [blame]
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +00001Kernel driver lm75
2==================
3
4Supported chips:
5 * National Semiconductor LM75
6 Prefix: 'lm75'
7 Addresses scanned: I2C 0x48 - 0x4f
8 Datasheet: Publicly available at the National Semiconductor website
9 http://www.national.com/
Len Sorensen05e82fe2011-03-21 17:59:36 +010010 * National Semiconductor LM75A
11 Prefix: 'lm75a'
12 Addresses scanned: I2C 0x48 - 0x4f
13 Datasheet: Publicly available at the National Semiconductor website
14 http://www.national.com/
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000015 * Dallas Semiconductor DS75
16 Prefix: 'lm75'
17 Addresses scanned: I2C 0x48 - 0x4f
18 Datasheet: Publicly available at the Dallas Semiconductor website
19 http://www.maxim-ic.com/
20 * Dallas Semiconductor DS1775
21 Prefix: 'lm75'
22 Addresses scanned: I2C 0x48 - 0x4f
23 Datasheet: Publicly available at the Dallas Semiconductor website
24 http://www.maxim-ic.com/
25 * Maxim MAX6625, MAX6626
26 Prefix: 'lm75'
27 Addresses scanned: I2C 0x48 - 0x4b
28 Datasheet: Publicly available at the Maxim website
29 http://www.maxim-ic.com/
30 * Microchip (TelCom) TCN75
31 Prefix: 'lm75'
32 Addresses scanned: I2C 0x48 - 0x4f
33 Datasheet: Publicly available at the Microchip website
34 http://www.microchip.com/
35
36Author: Frodo Looijaard <frodol@dds.nl>
37
38Description
39-----------
40
41The LM75 implements one temperature sensor. Limits can be set through the
42Overtemperature Shutdown register and Hysteresis register. Each value can be
43set and read to half-degree accuracy.
44An alarm is issued (usually to a connected LM78) when the temperature
45gets higher then the Overtemperature Shutdown value; it stays on until
46the temperature falls below the Hysteresis value.
47All temperatures are in degrees Celsius, and are guaranteed within a
48range of -55 to +125 degrees.
49
50The LM75 only updates its values each 1.5 seconds; reading it more often
51will do no harm, but will return 'old' values.
52
53The LM75 is usually used in combination with LM78-like chips, to measure
54the temperature of the processor(s).
55
56The DS75, DS1775, MAX6625, and MAX6626 are supported as well.
57They are not distinguished from an LM75. While most of these chips
58have three additional bits of accuracy (12 vs. 9 for the LM75),
59the additional bits are not supported. Not only that, but these chips will
60not be detected if not in 9-bit precision mode (use the force parameter if
61needed).
62
63The TCN75 is supported as well, and is not distinguished from an LM75.
64
65The LM75 is essentially an industry standard; there may be other
66LM75 clones not listed here, with or without various enhancements,
67that are supported.
68
69The LM77 is not supported, contrary to what we pretended for a long time.
70Both chips are simply not compatible, value encoding differs.