A terminal comprising: a charging interface including a data line; a first charging circuit coupled with the charging interface, the first charging circuit being configured to receive an output voltage from an adapter and apply the output voltage directly to both ends of multiple cells connected in series and included in the terminal to charge the multiple cells without voltage converting; a control unit configured to perform two-way communication with the adapter via the data line to control charging of the multiple cells; and a step-down circuit, having input ends and an output end, the input ends being coupled with both ends of the multiple cells and configured to convert an overall voltage of the multiple cells into a first voltage V1, wherein a≤V1≤b, a representing the minimum operating voltage of the terminal, and b representing the maximum operating voltage of the terminal; a power supply circuit, coupled to the output end of the step-down circuit and configured to supply power to the terminal based on the first voltage V1; and a second charging circuit that comprises a step-up circuit, the step-up circuit having one end coupled with the charging interface and the other end coupled with the multiple cells, the step-up circuit being configured to receive the output voltage of the adapter via the charging interface, step up the output voltage of the adapter to a second voltage, and apply the second voltage to both ends of the multiple cells for charging; the output voltage of the adapter received by the second charging circuit being less than the overall voltage of the multiple cells, the second voltage being greater than the overall voltage of the multiple cells; wherein the first charging circuit is operable in a quick charging mode, the second charging circuit is operable in a normal charging mode, and a charging speed of the terminal in the quick charging mode is higher than the charging speed of the terminal in the normal charging mode; characterized in that the control unit is further configured to: perform two-way communication with the adapter to determine a charging mode; and switch between the first charging circuit to charge the multiple cells through the first charging circuit upon determining that the terminal will be charged with the quick charging mode and the second charging circuit to charge the multiple cells through the second charging circuit upon determining that terminal will be charged with the normal charging mode. a charging interface including a data line; a first charging circuit coupled with the charging interface, the first charging circuit being configured to receive an output voltage from an adapter and apply the output voltage directly to both ends of multiple cells connected in series and included in the terminal to charge the multiple cells without voltage converting; a control unit configured to perform two-way communication with the adapter via the data line to control charging of the multiple cells; and a step-down circuit, having input ends and an output end, the input ends being coupled with both ends of the multiple cells and configured to convert an overall voltage of the multiple cells into a first voltage V1, wherein a≤V1≤b, a representing the minimum operating voltage of the terminal, and b representing the maximum operating voltage of the terminal; a power supply circuit, coupled to the output end of the step-down circuit and configured to supply power to the terminal based on the first voltage V1; and a second charging circuit that comprises a step-up circuit, the step-up circuit having one end coupled with the charging interface and the other end coupled with the multiple cells, the step-up circuit being configured to receive the output voltage of the adapter via the charging interface, step up the output voltage of the adapter to a second voltage, and apply the second voltage to both ends of the multiple cells for charging; the output voltage of the adapter received by the second charging circuit being less than the overall voltage of the multiple cells, the second voltage being greater than the overall voltage of the multiple cells; wherein the first charging circuit is operable in a quick charging mode, the second charging circuit is operable in a normal charging mode, and a charging speed of the terminal in the quick charging mode is higher than the charging speed of the terminal in the normal charging mode; characterized in that the control unit is further configured to: perform two-way communication with the adapter to determine a charging mode; and switch between the first charging circuit to charge the multiple cells through the first charging circuit upon determining that the terminal will be charged with the quick charging mode and the second charging circuit to charge the multiple cells through the second charging circuit upon determining that terminal will be charged with the normal charging mode. perform two-way communication with the adapter to determine a charging mode; and switch between the first charging circuit to charge the multiple cells through the first charging circuit upon determining that the terminal will be charged with the quick charging mode and the second charging circuit to charge the multiple cells through the second charging circuit upon determining that terminal will be charged with the normal charging mode.