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- Supported chips:
- * Dialog Semiconductors DA9052-BC and DA9053-AA/Bx PMICs
- Prefix: 'da9052'
- Datasheet: Datasheet is not publicly available.
- Authors: David Dajun Chen <dchen@diasemi.com>
- Description
- -----------
- The DA9052/53 provides an Analogue to Digital Converter (ADC) with 10 bits
- resolution and track and hold circuitry combined with an analogue input
- multiplexer. The analogue input multiplexer will allow conversion of up to 10
- different inputs. The track and hold circuit ensures stable input voltages at
- the input of the ADC during the conversion.
- The ADC is used to measure the following inputs:
- Channel 0: VDDOUT - measurement of the system voltage
- Channel 1: ICH - internal battery charger current measurement
- Channel 2: TBAT - output from the battery NTC
- Channel 3: VBAT - measurement of the battery voltage
- Channel 4: ADC_IN4 - high impedance input (0 - 2.5V)
- Channel 5: ADC_IN5 - high impedance input (0 - 2.5V)
- Channel 6: ADC_IN6 - high impedance input (0 - 2.5V)
- Channel 7: XY - TSI interface to measure the X and Y voltage of the touch
- screen resistive potentiometers
- Channel 8: Internal Tjunc. - sense (internal temp. sensor)
- Channel 9: VBBAT - measurement of the backup battery voltage
- By using sysfs attributes we can measure the system voltage VDDOUT, the battery
- charging current ICH, battery temperature TBAT, battery junction temperature
- TJUNC, battery voltage VBAT and the back up battery voltage VBBAT.
- Voltage Monitoring
- ------------------
- Voltages are sampled by a 10 bit ADC.
- The battery voltage is calculated as:
- Milli volt = ((ADC value * 1000) / 512) + 2500
- The backup battery voltage is calculated as:
- Milli volt = (ADC value * 2500) / 512;
- The voltages on ADC channels 4, 5 and 6 are calculated as:
- Milli volt = (ADC value * 2500) / 1023
- Temperature Monitoring
- ----------------------
- Temperatures are sampled by a 10 bit ADC. Junction and battery temperatures
- are monitored by the ADC channels.
- The junction temperature is calculated:
- Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8
- The junction temperature attribute is supported by the driver.
- The battery temperature is calculated:
- Degree Celsius = 1 / (t1 + 1/298)- 273
- where t1 = (1/B)* ln(( ADCval * 2.5)/(R25*ITBAT*255))
- Default values of R25, B, ITBAT are 10e3, 3380 and 50e-6 respectively.
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