AN INTEGRADED CIRCUIT COMPRISING A DAC WITH PROVISION FOR SETTING THE DAC TO A CLEAR CONDITION, AND A METHOD FOR SETTING A DAC TO A CLEAR CONDITION

摘要

A multi-channel integrated circuit comprises a plurality of channels (CH1 to CH20). A DAC (3) is provided in each channel (CH1 to CH20) for converting digital data inputted to the circuit (1) through an I/O port (14). Digital data to be converted by the DACs (3) is selectively applied to input registers (10) of each channel (CH1 to CH20) on a digital data bus (16) under the control of an interface and control logic circuit (15). The digital words written to the input registers (10) are in turn written to DAC registers (9) through corresponding digital switches (12) for conversion by the DACs (3). A clear code register (22) stores a clear code for writing to the DAC registers (9) in response to a clear signal applied to a clear terminal (24) of the circuit (1) so that analogue outputs appearing on output terminals (5) of the channels (CH1 to CH20) are of a predetermined value, typically, zero volts, when the circuit (1) is set in a clear condition. The clear code is written to the clear code register (22) through the I/O port (14) and the interface and control logic circuit (15).