The invention discloses a DC-DC variable voltage output circuit and a terminal device. The first end of an inductor is connected with an output pin of a DC-DC converter, the first end of a first resistor and the first end of a second resistor are both connected to the feedback pin of the DC-DC converter, the second end of the inductor and the second end of the first resistor are connected and serve as the output end of the DC-DC variable voltage output circuit, and the second end of the second resistor is grounded to form a feedback circuit during normal working of the DC-DC, the negative electrode of a diode is connected with the feedback pin of the DC-DC converter, and the positive electrode of the diode is connected with the first end of a third resistor to form an additional feedback circuit. By controlling the additional feedback circuit through the control voltage, when a TV system is in standby state, the additional feedback circuit affects the feedback signal of DC-DC, and theDC-DC output voltage is lowered, so that the input and output voltage difference of a low dropout regulator LDO network of the back end is reduced, and LDO efficiency is improved, thereby achieving the effect of improving efficiency and achieving the effect of standby low power consumption.