Analog-to-digital converter for both m-bit and n-bit analog conversion

DETAILED DESCRIPTION The present invention is made to overcome the problems.
It is therefore an object of the present invention to provide an m-bit A/D converter which can convert analog input signals into both m-bit digital signals and n-bit (n is smaller than m) digital signals.
In accordance with one aspect of the present invention, there is provided an analog-to-digital converter comprising a first data register for storing an m-bit analog-to-digital conversion result, a second data register for storing an n-bit (n is smaller than m) analog-to-digital conversion result, and an A/D conversion control circuit for transferring the n (n is smaller than m) highmost or lowermost bits of the m-bit analog-to-digital conversion result stored in the first data register as an n-bit analog-to-digital conversion result to the second data register.
Preferably, the n-bit analog-to-digital conversion result can be mapped into the second data register in such a manner that the n-bit analog-to-digital conversion result is stored in half-word units.
Alternatively, the n-bit analog-to-digital conversion result can be mapped into the second data register in such a manner that the n-bit analog-to-digital conversion result is stored in byte units.
In accordance with another aspect of the present invention, there is provided an analog-to-digital converter comprising a data register for storing an m-bit analog-to-digital conversion result, and a shifter being responsive to a first control signal applied thereto, for reading the m-bit analog-to-digital conversion result from the data register and then sending out the m-bit analog-to-digital conversion result, just as it is, and being responsive to a second control signal applied thereto, for reading the m-bit analog-to-digital conversion result from the data register and extracting the n (n is smaller than m) highmost or lowermost bits of the m-bit analog-to-digital conversion result, and then sending out the n-bit highmost or lowermost bits as an n-bit analog-to-digital conversion result