1 Kernel driver da9052 2 ==================== 3 4 Supported chips: 5 6 * Dialog Semiconductors DA9052-BC and DA9053-AA/Bx PMICs 7 8 Prefix: 'da9052' 9 10 Datasheet: Datasheet is not publicly available. 11 12 Authors: David Dajun Chen <dchen@diasemi.com> 13 14 Description 15 ----------- 16 17 The DA9052/53 provides an Analogue to Digital Converter (ADC) with 10 bits 18 resolution and track and hold circuitry combined with an analogue input 19 multiplexer. The analogue input multiplexer will allow conversion of up to 10 20 different inputs. The track and hold circuit ensures stable input voltages at 21 the input of the ADC during the conversion. 22 23 The ADC is used to measure the following inputs: 24 25 ========= =================================================================== 26 Channel 0 VDDOUT - measurement of the system voltage 27 Channel 1 ICH - internal battery charger current measurement 28 Channel 2 TBAT - output from the battery NTC 29 Channel 3 VBAT - measurement of the battery voltage 30 Channel 4 ADC_IN4 - high impedance input (0 - 2.5V) 31 Channel 5 ADC_IN5 - high impedance input (0 - 2.5V) 32 Channel 6 ADC_IN6 - high impedance input (0 - 2.5V) 33 Channel 7 XY - TSI interface to measure the X and Y voltage of the touch 34 screen resistive potentiometers 35 Channel 8 Internal Tjunc. - sense (internal temp. sensor) 36 Channel 9 VBBAT - measurement of the backup battery voltage 37 ========= =================================================================== 38 39 By using sysfs attributes we can measure the system voltage VDDOUT, the battery 40 charging current ICH, battery temperature TBAT, battery junction temperature 41 TJUNC, battery voltage VBAT and the back up battery voltage VBBAT. 42 43 Voltage Monitoring 44 ------------------ 45 46 Voltages are sampled by a 10 bit ADC. 47 48 The battery voltage is calculated as: 49 50 Milli volt = ((ADC value * 1000) / 512) + 2500 51 52 The backup battery voltage is calculated as: 53 54 Milli volt = (ADC value * 2500) / 512; 55 56 The voltages on ADC channels 4, 5 and 6 are calculated as: 57 58 Milli volt = (ADC value * 2500) / 1023 59 60 Temperature Monitoring 61 ---------------------- 62 63 Temperatures are sampled by a 10 bit ADC. Junction and battery temperatures 64 are monitored by the ADC channels. 65 66 The junction temperature is calculated: 67 68 Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8 69 70 The junction temperature attribute is supported by the driver. 71 72 The battery temperature is calculated: 73 74 Degree Celsius = 1 / (t1 + 1/298) - 273 75 76 where t1 = (1/B)* ln(( ADCval * 2.5)/(R25*ITBAT*255)) 77 78 Default values of R25, B, ITBAT are 10e3, 3380 and 50e-6 respectively.
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