Current-output type digital-to-analog converter

A load driving apparatus comprising:

• a current-output type digital-to-analog converter which generates an output current according to an input n-bit (n is a natural number) digital signal and outputs the output current from a current output terminal;
• and
• a voltage generation unit which supplies a drive voltage to a load circuit connected to the current output terminal of the current-output type digital-to-analog converter, wherein
• the current-output type digital-to-analog converter includes:
• n output transistors each of which has a first terminal, the potential of which is fixed by a common fixed voltage and a second terminal located on a side opposite the first terminal and connected to the current output terminal;
• an input transistor of which has a first terminal and a control terminal commonly connected to those of the n output transistors;
• a first current-to-voltage conversion unit which is connected onto a second terminal side of the input transistor to convert a current flowing through the input transistor into a voltage;
• a constant current source which generates a reference current;
• a second current-to-voltage conversion unit which converts the reference current into a voltage;
• a first error amplifier to which, each of output voltages of the first and second current-to-voltage conversion units are input to adjust voltages at the control terminals of the input transistor and the n output transistors;
• an switches which are provided on a path through which an output of the first error amplifier reaches the control terminals of the n output transistors;
• and
• a control unit which controls on/off of the n switches according to the n-bit digital signal.