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BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
Programming Considerations
During microcontroller operations where the A/D converter is not being used, the A/D internal
circuitry can be switched off to reduce power consumption, by setting bit ADCEN low in the ADCR
register. When this happens, the internal A/D converter circuits will not consume power irrespective
of what analog voltage is applied to their input lines. If the A/D converter input lines are used as
normal I/Os, then care must be taken as if the input voltage is not at a valid logic level, then this may
lead to some increase in power consumption.
A/D Transfer Function
As the devices contain a 12-bit A/D converter, its full-scale converted digitised value is equal to
FFFH. Since the full-scale analog input value is equal to the reference voltage, this gives a single bit
analog input value of reference voltage value divided by 4096.
1 LSB=V
REF
÷ 4096
The A/D Converter input voltage value can be calculated using the following equation:
A/D input voltage=A/D output digital value × V
REF
÷ 4096
The diagram shows the ideal transfer function between the analog input value and the digitised
output value for the A/D converter. Except for the digitised zero value, the subsequent digitised
values will change at a point 0.5 LSB below where they would change without the offset, and the
last full scale digitised value will change at a point 1.5 LSB below the V
REF
level.
Ideal A/D Transfer Function