A/D conversion device having input level shift and output correction function
AssigneeDenso Corporation
InventorTakuya Harada
Life of this patent
Estimating the term…
Abstract
In an A/D conversion device, one level shift circuit shifts an input voltage to the low potential side by Vt1, and another level shift circuit shifts the input voltage to the high potential side by Vt2. A multiplexer selects either of the shifted voltages to an A/D converter. In a correction mode, a correction data holding circuit holds values of reference voltages that are also A/D converted after being passed through the one level shift circuit and values of reference voltages that are A/D converted by being passed through the other level shift circuit, as correction values. A correction control circuit corrects the A/D converted value using the correction values.
Claims8
An A/D conversion device comprising:
- an input line for receiving a conversion object voltage;
- a first level shift circuit that shifts the conversion object voltage applied to the input line to a first object voltage, which is on a low potential side by a first offset voltage;
- a second level shift circuit that shifts the conversion object voltage applied to the input line to a second object voltage, which is on a high potential side by a second offset voltage;
- a selection circuit that selects the first object voltage outputted from the first level shift circuit when the conversion object voltage is equal to or more than a predetermined threshold, and selects the second object voltage outputted from the second level shift circuit when the conversion object voltage is less than the predetermined threshold;
- an A/D converter that takes in the voltage selected by the selection circuit and A/D converts it in a predetermined voltage range;
- and
- correcting means for correcting an A/D converted value outputted from the A/D converter according to a selection state of the selection circuit.
An A/D conversion device comprising:
- a plurality of input lines for receiving conversion object voltages, respectively;
- a plurality of first level shift circuits provided in correspondence with the input lines, the first level shift circuits shifting the conversion object voltages applied to the input lines to first object voltages, which are on a low potential side by a first offset voltage, respectively;
- a plurality of second level shift circuits provided in correspondence with the input lines, the second level shift circuits shifting the conversion object voltages applied to the input lines to second object voltages, which are on a high potential side by a second offset voltage, respectively;
- a multiplexer that outputs one of the first object voltages and one of the second object voltages corresponding to one of the conversion object voltages of a specified one of the input lines;
- a selection circuit that selects the one of the first object voltages outputted from the one of the first level shift circuits when the one of the conversion object voltages is equal to or more than a predetermined threshold, and selects the one of the second object voltages outputted from the one of the second level shift circuits when the one of the conversion object voltages is less than the predetermined threshold;
- an A/D converter that takes in the voltage selected by the selection circuit and A/D converts it in a predetermined voltage range;
- and
- correcting means for correcting an A/D converted value outputted from the A/D converter according to a selection state of the selection circuit.
Dependencies are inferred from the claim text.