JAJSEF7G December 2014 – February 2019 TPS659037
PRODUCTION DATA.
The GPADC consists of a 12-bit sigma-delta ADC combined with an analog input multiplexer. The GPADC allows the host processor to monitor a variety of analog signals using analog-to-digital conversion on the input source. After the conversion completes, an interrupt is generated for the host processor and it can read the result of the conversion through the I2C interface.
The GPADC on this PMIC supports 16 analog inputs. However only a total of 9 inputs are available for the application use. Three of these inputs are available on external pins, and the remaining six are dedicated to internal resource monitoring. One of the three external inputs is associated with a current source allowing measurements of resistive elements (thermal sensor). To improve the measurement accuracy, the reference voltages GPADC_VREF can be used with an external resistor for the NTC resistor measurement. The reference voltage GPADC_VREF is always present when the GPADC is enabled.
GPADC_IN0 is associated with three selectable current sources. The selectable current levels are 5, 15, and 20 μA.
GPADC_IN1 is intended to measure temperature with an NTC sensor connected to ground. Two resistors, one in parallel with the NTC resistor and the other one between GPADC_IN1 and GPADC_VREF, can be used to modify the exponential function of the NTC resistor.
Figure 5-9 shows the block diagram of the GPADC.
For all the measurements performed by the monitoring GPADC, voltage dividers, current to voltage converters, and current source are integrated in the TPS659037 device to scale the signal to be measured to the GPADC input range.
The conversion requests are initiated by the host processor either by software through the I2C. This mode is useful when real-time conversion is required.
Two kinds of conversion requests are available with the following priority:
The EXTEND_DELAY bit in the GPADC_RT_CTRL register can extend by 400 μs the delay from the channel selection or triggering to the sampling.
Use Equation 4 to convert from the GPADC code to the internal die temperature using GPADC channels 12 and 13.
CHANNEL | TYPE | INPUT VOLTAGE FULL RANGE(1) | INPUT VOLTAGE PERFORMANCE RANGE(2) | SCALER | OPERATION |
---|---|---|---|---|---|
0 (GPADC_IN0) | External(3) | 0 to 1.25 V | 0.01 to 1.215 V | No | Resistor value or general purpose. Select source current 0, 5, 15, or 20 μA |
1 (GPADC_IN1) | External(3) | 0 to 1.25 V | 0.01 to 1.215 V | No | Platform temperature, NTC resistor value and general purpose |
2 (GPADC_IN2) | External(3) | 0 to 2.5 V | 0.02 to 2.43 V | 2 | Audio accessory or general purpose |
7 (VCC_SENSE) | Internal | 2.5 to 5 V when HIGH_VCC_SENSE = 0
2.3 V to (VCC1–1 V) when HIGH_VCC_SENSE = 1 |
2.5 to 4.86 V when HIGH_VCC_SENSE = 0
2.3 V to (VCC1–1 V) when HIGH_VCC_SENSE = 1 |
4 | System supply voltage (VCC_SENSE) |
10 (VBUS) | Internal | 0 to 6.875V | 0.055 to 5.25 V | 5.5 | VBUS Voltage |
11 | Internal | 0 to 1.25 V | No | DC-DC current probe | |
12 | Internal | 0 to 1.25 V | 0 to 1.215 V | No | PMIC internal die temperature |
13 | Internal | 0 to 1.25 V | 0 to 1.215 V | No | PMIC internal die temperature |
15 | Internal | 0 to VCC1 V | 0.055 to VCC1 V | 5 | Test network |