A microprocessor-compatible high-speed 8-bit DAC

The increasing use of microprocessors in systems which receive or generate analog signals has created a need for data converters which interface to those processors. A D/A converter which includes all registers and logic required for 8-bit microprocessor interface, and can be fabricated with a standard bipolar linear process is described. The system interface timing is specified such that the converter appears as a memory location to the microprocessor. It can be programmed to operate in a wide variety of modes and can interface with the fastest MOS and TTL microprocessors. The converter offers high-speed multiplying operation and an output current mode multiplexer. Status latches are provided to store multiplexer and code select commands. Nonsaturating multilevel logic operating nearly in the linear region provides gate delays of less than 5 ns when fabricated on the same chip with precision linear functions.