linux/Documentation/hwmon/ntc_thermistor
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   1Kernel driver ntc_thermistor
   2=================
   3
   4Supported thermistors:
   5* Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473, NCP15WL333
   6  Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473', 'ncp15wl333'
   7  Datasheet: Publicly available at Murata
   8
   9Other NTC thermistors can be supported simply by adding compensation
  10tables; e.g., NCP15WL333 support is added by the table ncpXXwl333.
  11
  12Authors:
  13        MyungJoo Ham <myungjoo.ham@samsung.com>
  14
  15Description
  16-----------
  17
  18The NTC thermistor is a simple thermistor that requires users to provide the
  19resistance and lookup the corresponding compensation table to get the
  20temperature input.
  21
  22The NTC driver provides lookup tables with a linear approximation function
  23and four circuit models with an option not to use any of the four models.
  24
  25The four circuit models provided are:
  26
  27        $: resister, [TH]: the thermistor
  28
  29 1. connect = NTC_CONNECTED_POSITIVE, pullup_ohm > 0
  30
  31   [pullup_uV]
  32       |    |
  33      [TH]  $ (pullup_ohm)
  34       |    |
  35       +----+-----------------------[read_uV]
  36       |
  37       $ (pulldown_ohm)
  38       |
  39      --- (ground)
  40
  41 2. connect = NTC_CONNECTED_POSITIVE, pullup_ohm = 0 (not-connected)
  42
  43   [pullup_uV]
  44       |
  45      [TH]
  46       |
  47       +----------------------------[read_uV]
  48       |
  49       $ (pulldown_ohm)
  50       |
  51      --- (ground)
  52
  53 3. connect = NTC_CONNECTED_GROUND, pulldown_ohm > 0
  54
  55   [pullup_uV]
  56       |
  57       $ (pullup_ohm)
  58       |
  59       +----+-----------------------[read_uV]
  60       |    |
  61      [TH]  $ (pulldown_ohm)
  62       |    |
  63      -------- (ground)
  64
  65 4. connect = NTC_CONNECTED_GROUND, pulldown_ohm = 0 (not-connected)
  66
  67   [pullup_uV]
  68       |
  69       $ (pullup_ohm)
  70       |
  71       +----------------------------[read_uV]
  72       |
  73      [TH]
  74       |
  75      --- (ground)
  76
  77When one of the four circuit models is used, read_uV, pullup_uV, pullup_ohm,
  78pulldown_ohm, and connect should be provided. When none of the four models
  79are suitable or the user can get the resistance directly, the user should
  80provide read_ohm and _not_ provide the others.
  81
  82Sysfs Interface
  83---------------
  84name            the mandatory global attribute, the thermistor name.
  85
  86temp1_type      always 4 (thermistor)
  87                RO
  88
  89temp1_input     measure the temperature and provide the measured value.
  90                (reading this file initiates the reading procedure.)
  91                RO
  92
  93Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists.
  94
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