/kern_oII/Documentation/hwmon/lm75

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  1. Kernel driver lm75
    2. 

  2. ==================
    3. 

  3. 

  4. Supported chips:
    5. 

  5.   * National Semiconductor LM75
    6. 

  6.     Prefix: 'lm75'
    7. 

  7.     Addresses scanned: I2C 0x48 - 0x4f
    8. 

  8.     Datasheet: Publicly available at the National Semiconductor website
    9. 

  9.                http://www.national.com/
    10. 

  10.   * Dallas Semiconductor DS75
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  11.     Prefix: 'lm75'
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  12.     Addresses scanned: I2C 0x48 - 0x4f
    13. 

  13.     Datasheet: Publicly available at the Dallas Semiconductor website
    14. 

  14.                http://www.maxim-ic.com/
    15. 

  15.   * Dallas Semiconductor DS1775
    16. 

  16.     Prefix: 'lm75'
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  17.     Addresses scanned: I2C 0x48 - 0x4f
    18. 

  18.     Datasheet: Publicly available at the Dallas Semiconductor website
    19. 

  19.                http://www.maxim-ic.com/
    20. 

  20.   * Maxim MAX6625, MAX6626
    21. 

  21.     Prefix: 'lm75'
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  22.     Addresses scanned: I2C 0x48 - 0x4b
    23. 

  23.     Datasheet: Publicly available at the Maxim website
    24. 

  24.                http://www.maxim-ic.com/
    25. 

  25.   * Microchip (TelCom) TCN75
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  26.     Prefix: 'lm75'
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  27.     Addresses scanned: I2C 0x48 - 0x4f
    28. 

  28.     Datasheet: Publicly available at the Microchip website
    29. 

  29.                http://www.microchip.com/
    30. 

  30. 

  31. Author: Frodo Looijaard <frodol@dds.nl>
    32. 

  32. 

  33. Description
    34. 

  34. -----------
    35. 

  35. 

  36. The LM75 implements one temperature sensor. Limits can be set through the
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  37. Overtemperature Shutdown register and Hysteresis register. Each value can be
    38. 

  38. set and read to half-degree accuracy.
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  39. An alarm is issued (usually to a connected LM78) when the temperature
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  40. gets higher then the Overtemperature Shutdown value; it stays on until
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  41. the temperature falls below the Hysteresis value.
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  42. All temperatures are in degrees Celsius, and are guaranteed within a
    43. 

  43. range of -55 to +125 degrees.
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  44. 

  45. The LM75 only updates its values each 1.5 seconds; reading it more often
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  46. will do no harm, but will return 'old' values.
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  47. 

  48. The LM75 is usually used in combination with LM78-like chips, to measure
    49. 

  49. the temperature of the processor(s).
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  50. 

  51. The DS75, DS1775, MAX6625, and MAX6626 are supported as well.
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  52. They are not distinguished from an LM75. While most of these chips
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  53. have three additional bits of accuracy (12 vs. 9 for the LM75),
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  54. the additional bits are not supported. Not only that, but these chips will
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  55. not be detected if not in 9-bit precision mode (use the force parameter if
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  56. needed).
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  57. 

  58. The TCN75 is supported as well, and is not distinguished from an LM75.
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  59. 

  60. The LM75 is essentially an industry standard; there may be other
    61. 

  61. LM75 clones not listed here, with or without various enhancements,
    62. 

  62. that are supported.
    63. 

  63. 

  64. The LM77 is not supported, contrary to what we pretended for a long time.
    65. 

  65. Both chips are simply not compatible, value encoding differs.
    66.