Method of controlling analog-to-digital converter

A method of controlling an analog-to-digital converter for converting an input voltage into digital data, comprising:

• charging a first capacitor with an input voltage to be converted into digital data;
• charging a second capacitor with a basic voltage;
• disconnecting the input voltage from the first capacitor;
• disconnecting the basic voltage from the second capacitor;
• obtaining uppermost bits of the digital data, including:
• generating a first reference voltage to be compared to the input voltage, wherein generating the first reference voltage includes supplying first digital control data from a control circuit to a digital-to-analog (D/A) converting unit;
• applying the first reference voltage to the first capacitor, wherein applying the first reference voltage to the first capacitor includes turning on a first switch connected between the D/A converting unit and the first capacitor;
• applying a first constant voltage furnished by the D/A converting unit to the second capacitor, wherein applying the first constant voltage to the second capacitor includes turning on a second switch connected between the D/A converting unit and the second capacitor;
• determining new digital control data to be furnished by the control circuit according to relationship between voltages applied to the first and second capacitor;
• supplying the new digital control data from the control circuit to the D/A converting unit to change the first reference voltage to a new value;
• and
• before the first reference voltage begins a transition to a new value, turning off the first switch and keeping the first switch off until the first reference voltage from the D/A converting unit becomes stable;
• and
• obtaining remaining lowermost bits of the digital data including:
• applying a second constant voltage generated by the D/A converting unit, the second constant voltage having a value corresponding to binary data of the uppermost bits and zeros for the lowermost bits, to the first capacitor, wherein applying the second constant voltage includes turning on the first switch;
• applying a second reference voltage generated by the D/A converting unit from digital control data from the control circuit to the second capacitor, wherein applying the second reference voltage to the second capacitor includes turning the second switch on;
• determining second new digital control data to be furnished by the control circuit according to a relationship between voltages applied to the first and second capacitors;
• applying the second new digital control data from the control circuit to the D/A converting unit to change the second reference voltage to a new value;
• and
• before the second reference voltage changes to a new value, turning off the second switch and keeping the second switch off until the second reference voltage from the D/A converting unit becomes stable.