16-bit serial DAC module

A 16-bit DAC module made of two pieces of 74HC595 and an R-2R resistor array. The output part uses a rail-to-rail op amp to improve the output load capacity. Compared with cheap audio DACs, the DAC produced by R-2R has better linearity. The maximum output speed of the DAC depends on the 595 chip model used. The Toshiba 74HC595D used in the design can reach a communication frequency of 55MHz, which translates to a maximum output rate of 3MHz (not possible)

Precautions:

• Input voltage range is 3.0~5.5V
• The 595 chip with open drain output cannot be used
• The precision of the resistor will affect the output linearity to a great extent. Please use at least a 1% precision resistor. It is recommended to use a 0.5% precision resistor.
• If you want to further shrink the configuration and get the output voltage as close to 0V as possible, you can remove the output buffer op amp.
• The output is LSBFIRST

Physical picture:

Output sawtooth wave: