Linear power supply device and power supply system

A linear power supply device comprising:

• an output transistor including a first terminal configured to be capable of connecting to an application terminal of an input voltage, and a second terminal configured to be capable of connecting to a first feedback resistor among the first feedback resistor, a second feedback resistor, and a third feedback resistor, which are connected in series;
• a first error amplifier to which a reference voltage and a feedback voltage generated at a first node, at which the second feedback resistor and the third feedback resistor are connected, are input, the first error amplifier being configured to be capable of controlling a control terminal of the output transistor;
• an output terminal connected to a second terminal of the output transistor;
• a current transmission/reception terminal;
• a first mirror transistor configured to capable of generating a first mirror current of a current flowing in the output transistor;
• a second mirror transistor configured to capable of generating a second mirror current of the current flowing in the output transistor;
• a switch circuit configured to switch between outputting the first mirror current from the current transmission/reception terminal to the outside, and receiving an external mirror current from the outside through the current transmission/reception terminal, on the basis of a switching signal;
• and
• a comparison unit configured to compare the external mirror current with the second mirror current, so as to draw out current from a second node, at which the first feedback resistor and the second feedback resistor are connected, or to inject current into the second node, on the basis of the comparison result.