Provided are a charging circuit for a charger, a charging circuit for a mobile terminal, a charger (10), and a mobile terminal (20). The charging circuit for a charger comprises: a voltage conversion circuit (101) used to convert an alternating current to a direct current and connected to an alternating current charging source; a first charging interface (102) used to connect to a second charging interface (201) of the mobile terminal (20), the first charging interface (102) comprising a voltage output terminal connected to the voltage conversion circuit (101) and multiple first data transmission terminals; and a first control circuit (103), one end of the first control circuit (103) being connected to the voltage conversion circuit (101), and another end of the first control circuit (103) being connected to at least one of the first data transmission terminals.
