The serial interface is double-buffered. A 16-bit input shift register is followed by eight 8-bit input registers and eight 8-bit DAC registers. The 16-bit serial word consists of two "don't care" bits, three address bits, three control bits, and eight data bits. The input and DAC registers can both be updated independently or simultaneously with a single software command. The asynchronous control input (LDAC) provides simultaneous updating of all eight DAC registers.