0001 Kernel driver da9052
0002 ====================
0003
0004 Supported chips:
0005
0006 * Dialog Semiconductors DA9052-BC and DA9053-AA/Bx PMICs
0007
0008 Prefix: 'da9052'
0009
0010 Datasheet: Datasheet is not publicly available.
0011
0012 Authors: David Dajun Chen <dchen@diasemi.com>
0013
0014 Description
0015 -----------
0016
0017 The DA9052/53 provides an Analogue to Digital Converter (ADC) with 10 bits
0018 resolution and track and hold circuitry combined with an analogue input
0019 multiplexer. The analogue input multiplexer will allow conversion of up to 10
0020 different inputs. The track and hold circuit ensures stable input voltages at
0021 the input of the ADC during the conversion.
0022
0023 The ADC is used to measure the following inputs:
0024
0025 ========= ===================================================================
0026 Channel 0 VDDOUT - measurement of the system voltage
0027 Channel 1 ICH - internal battery charger current measurement
0028 Channel 2 TBAT - output from the battery NTC
0029 Channel 3 VBAT - measurement of the battery voltage
0030 Channel 4 ADC_IN4 - high impedance input (0 - 2.5V)
0031 Channel 5 ADC_IN5 - high impedance input (0 - 2.5V)
0032 Channel 6 ADC_IN6 - high impedance input (0 - 2.5V)
0033 Channel 7 XY - TSI interface to measure the X and Y voltage of the touch
0034 screen resistive potentiometers
0035 Channel 8 Internal Tjunc. - sense (internal temp. sensor)
0036 Channel 9 VBBAT - measurement of the backup battery voltage
0037 ========= ===================================================================
0038
0039 By using sysfs attributes we can measure the system voltage VDDOUT, the battery
0040 charging current ICH, battery temperature TBAT, battery junction temperature
0041 TJUNC, battery voltage VBAT and the back up battery voltage VBBAT.
0042
0043 Voltage Monitoring
0044 ------------------
0045
0046 Voltages are sampled by a 10 bit ADC.
0047
0048 The battery voltage is calculated as:
0049
0050 Milli volt = ((ADC value * 1000) / 512) + 2500
0051
0052 The backup battery voltage is calculated as:
0053
0054 Milli volt = (ADC value * 2500) / 512;
0055
0056 The voltages on ADC channels 4, 5 and 6 are calculated as:
0057
0058 Milli volt = (ADC value * 2500) / 1023
0059
0060 Temperature Monitoring
0061 ----------------------
0062
0063 Temperatures are sampled by a 10 bit ADC. Junction and battery temperatures
0064 are monitored by the ADC channels.
0065
0066 The junction temperature is calculated:
0067
0068 Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8
0069
0070 The junction temperature attribute is supported by the driver.
0071
0072 The battery temperature is calculated:
0073
0074 Degree Celsius = 1 / (t1 + 1/298) - 273
0075
0076 where t1 = (1/B)* ln(( ADCval * 2.5)/(R25*ITBAT*255))
0077
0078 Default values of R25, B, ITBAT are 10e3, 3380 and 50e-6 respectively.
