TC35680FSG datasheet(59/91 Pages) TOSHIBA

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TC35680FSG-002/TC35681FSG-002

2019-04-04

4.11. ADC (AD Converter)

Feature

The TC35680/TC35681 integrates a 10/12-bit AD converter (ADC) that can be used for power supply voltage measurement and

measurement of General-purpose voltage such as an input voltage from an external sensor.

The ADC has the following features;



Reference I/O power supply: VDDIO



General-purpose voltage input pin count (shared with GPIO pins): 5 for QFN package



Power supply voltage measurement: 1 channel (ADC0) This pin is connect to VDDCORE2 (1.2-V voltage supply)

internally.



Maximum sampling rate: 1 MS/s (But the function which coverts an analog signal continuously is not supported)



10-bit conversion or 12-bit conversion can be selected (default is 10 bits).

For the general-purpose voltage input, the channels except channel 0 which is connected to VDDCORE2 can be used.

These channels are shared with the GPIO pins. When the ADC function is assigned to one of the GPIO pins, the corresponding pin

should be set to input standby and the pull-up and pull-down resistors should be disconnected. For the details of the GPIO pins, refer

to Section 2.4. And for the setting method of the pin, refer to Section 4.6.2.

The ADC function is set by the GPADCC_CTRL register. One of the channels is selected by the GPADCC_SELAIN register to

convert the analog signal input from the channel. The result data can be read from the GPADCC_DATA register. The 10-bit

conversion result is set to 11-bit to 2-bit in GPADCC_DATA register when the data length of the conversion result is specified as 10

bits. And the 12-bit conversion result is set to 11-bit to 0-bit in GPADCC_DATA register when the data length of the conversion result

is specified as 12 bits.

All channel data cannot be read out at the same time. The conversion end can be detected using a corresponding interrupt or the

polling method. The maximum sampling rate depends on the CPU utilization.

The pin of AD convertor for the measurement of General-purpose voltage should not be input the signal whose voltage is higher

than the voltage of the VDDIO.

Function

An analog signal in the range of 0 to VDDIO (V) can be input into an analog input channel of the general-purpose voltage

measurement. The reference voltage (VREFH) of the ADC is connected to VBAT internally, so the result of AD conversion is shown

as a relative value against the VBAT voltage as in the following equation.

Result of AD conversion

=4095×InputvoltagetoachannelofADC

VREFH(=VBATvoltage)

ADC0 for the power supply voltage measurement is connected to VDDCORE2 (1.2-V voltage supply) internally. The VBAT voltage

is shown by the channel 0’s result of AD conversion.

VBAT=4095×

1.2V

ResultofADconversionofchannel0

The absolute voltage of the analog input signal for the general-purpose voltage measurement is calculated using the following

equation.

ADCninputvoltage[V]=ResultofADconversionofchanneln

ResultofADconversionofchannel0×1.2[V]

The concept of the voltage conversion is shown in Figure 4-19.

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