Documentation/hwmon/lm75.rst

   1 Kernel driver lm75
   2 ==================
   3
   4 Supported chips:
   5
   6   * National Semiconductor LM75
   7
   8     Prefix: 'lm75'
   9
  10     Addresses scanned: I2C 0x48 - 0x4f
  11
  12     Datasheet: Publicly available at the National Semiconductor website
  13
  14                http://www.national.com/
  15
  16   * National Semiconductor LM75A
  17
  18     Prefix: 'lm75a'
  19
  20     Addresses scanned: I2C 0x48 - 0x4f
  21
  22     Datasheet: Publicly available at the National Semiconductor website
  23
  24                http://www.national.com/
  25
  26   * Dallas Semiconductor (now Maxim) DS75, DS1775, DS7505
  27
  28     Prefixes: 'ds75', 'ds1775', 'ds7505'
  29
  30     Addresses scanned: none
  31
  32     Datasheet: Publicly available at the Maxim website
  33
  34                http://www.maximintegrated.com/
  35
  36   * Maxim MAX6625, MAX6626, MAX31725, MAX31726
  37
  38     Prefixes: 'max6625', 'max6626', 'max31725', 'max31726'
  39
  40     Addresses scanned: none
  41
  42     Datasheet: Publicly available at the Maxim website
  43
  44                http://www.maxim-ic.com/
  45
  46   * Microchip (TelCom) TCN75
  47
  48     Prefix: 'tcn75'
  49
  50     Addresses scanned: none
  51
  52     Datasheet: Publicly available at the Microchip website
  53
  54                http://www.microchip.com/
  55
  56   * Microchip MCP9800, MCP9801, MCP9802, MCP9803
  57
  58     Prefix: 'mcp980x'
  59
  60     Addresses scanned: none
  61
  62     Datasheet: Publicly available at the Microchip website
  63
  64                http://www.microchip.com/
  65
  66   * Analog Devices ADT75
  67
  68     Prefix: 'adt75'
  69
  70     Addresses scanned: none
  71
  72     Datasheet: Publicly available at the Analog Devices website
  73
  74                http://www.analog.com/adt75
  75
  76   * ST Microelectronics STDS75
  77
  78     Prefix: 'stds75'
  79
  80     Addresses scanned: none
  81
  82     Datasheet: Publicly available at the ST website
  83
  84                http://www.st.com/internet/analog/product/121769.jsp
  85
  86   * ST Microelectronics STLM75
  87
  88     Prefix: 'stlm75'
  89
  90     Addresses scanned: none
  91
  92     Datasheet: Publicly available at the ST website
  93
  94                https://www.st.com/resource/en/datasheet/stlm75.pdf
  95
  96   * Texas Instruments TMP100, TMP101, TMP105, TMP112, TMP75, TMP75B, TMP75C, TMP175, TMP275
  97
  98     Prefixes: 'tmp100', 'tmp101', 'tmp105', 'tmp112', 'tmp175', 'tmp75', 'tmp75b', 'tmp75c', 'tmp275'
  99
 100     Addresses scanned: none
 101
 102     Datasheet: Publicly available at the Texas Instruments website
 103
 104                http://www.ti.com/product/tmp100
 105
 106                http://www.ti.com/product/tmp101
 107
 108                http://www.ti.com/product/tmp105
 109
 110                http://www.ti.com/product/tmp112
 111
 112                http://www.ti.com/product/tmp75
 113
 114                http://www.ti.com/product/tmp75b
 115
 116                http://www.ti.com/product/tmp75c
 117
 118                http://www.ti.com/product/tmp175
 119
 120                http://www.ti.com/product/tmp275
 121
 122   * NXP LM75B
 123
 124     Prefix: 'lm75b'
 125
 126     Addresses scanned: none
 127
 128     Datasheet: Publicly available at the NXP website
 129
 130                http://www.nxp.com/documents/data_sheet/LM75B.pdf
 131
 132 Author: Frodo Looijaard <frodol@dds.nl>
 133
 134 Description
 135 -----------
 136
 137 The LM75 implements one temperature sensor. Limits can be set through the
 138 Overtemperature Shutdown register and Hysteresis register. Each value can be
 139 set and read to half-degree accuracy.
 140 An alarm is issued (usually to a connected LM78) when the temperature
 141 gets higher then the Overtemperature Shutdown value; it stays on until
 142 the temperature falls below the Hysteresis value.
 143 All temperatures are in degrees Celsius, and are guaranteed within a
 144 range of -55 to +125 degrees.
 145
 146 The driver caches the values for a period varying between 1 second for the
 147 slowest chips and 125 ms for the fastest chips; reading it more often
 148 will do no harm, but will return 'old' values.
 149
 150 The original LM75 was typically used in combination with LM78-like chips
 151 on PC motherboards, to measure the temperature of the processor(s). Clones
 152 are now used in various embedded designs.
 153
 154 The LM75 is essentially an industry standard; there may be other
 155 LM75 clones not listed here, with or without various enhancements,
 156 that are supported. The clones are not detected by the driver, unless
 157 they reproduce the exact register tricks of the original LM75, and must
 158 therefore be instantiated explicitly. Higher resolution up to 16-bit
 159 is supported by this driver, other specific enhancements are not.
 160
 161 The LM77 is not supported, contrary to what we pretended for a long time.
 162 Both chips are simply not compatible, value encoding differs.