linux/Documentation/hwmon/da9052
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   1Supported chips:
   2  * Dialog Semiconductors DA9052-BC and DA9053-AA/Bx PMICs
   3    Prefix: 'da9052'
   4    Datasheet: Datasheet is not publicly available.
   5
   6Authors: David Dajun Chen <dchen@diasemi.com>
   7
   8Description
   9-----------
  10
  11The DA9052/53 provides an Analogue to Digital Converter (ADC) with 10 bits
  12resolution and track and hold circuitry combined with an analogue input
  13multiplexer. The analogue input multiplexer will allow conversion of up to 10
  14different inputs. The track and hold circuit ensures stable input voltages at
  15the input of the ADC during the conversion.
  16
  17The ADC is used to measure the following inputs:
  18Channel 0: VDDOUT - measurement of the system voltage
  19Channel 1: ICH - internal battery charger current measurement
  20Channel 2: TBAT - output from the battery NTC
  21Channel 3: VBAT - measurement of the battery voltage
  22Channel 4: ADC_IN4 - high impedance input (0 - 2.5V)
  23Channel 5: ADC_IN5 - high impedance input (0 - 2.5V)
  24Channel 6: ADC_IN6 - high impedance input (0 - 2.5V)
  25Channel 7: XY - TSI interface to measure the X and Y voltage of the touch
  26           screen resistive potentiometers
  27Channel 8: Internal Tjunc. - sense (internal temp. sensor)
  28Channel 9: VBBAT - measurement of the backup battery voltage
  29
  30By using sysfs attributes we can measure the system voltage VDDOUT, the battery
  31charging current ICH, battery temperature TBAT, battery junction temperature
  32TJUNC, battery voltage VBAT and the back up battery voltage VBBAT.
  33
  34Voltage Monitoring
  35------------------
  36
  37Voltages are sampled by a 10 bit ADC.
  38
  39The battery voltage is calculated as:
  40        Milli volt = ((ADC value * 1000) / 512) + 2500
  41
  42The backup battery voltage is calculated as:
  43        Milli volt = (ADC value * 2500) / 512;
  44
  45The voltages on ADC channels 4, 5 and 6 are calculated as:
  46        Milli volt = (ADC value * 2500) / 1023
  47
  48Temperature Monitoring
  49----------------------
  50
  51Temperatures are sampled by a 10 bit ADC.  Junction and battery temperatures
  52are monitored by the ADC channels.
  53
  54The junction temperature is calculated:
  55        Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8
  56The junction temperature attribute is supported by the driver.
  57
  58The battery temperature is calculated:
  59        Degree Celcius = 1 / (t1 + 1/298)- 273
  60where t1 = (1/B)* ln(( ADCval * 2.5)/(R25*ITBAT*255))
  61Default values of R25, B, ITBAT are 10e3, 3380 and 50e-6 respectively.
  62
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