A constant on-time isolated converter, connectable to an input terminal for receiving an input voltage, the isolated converter comprising: a transformer comprising a primary side and a secondary side, wherein the primary side is connectable to the input terminal and the secondary side is connectable to a load, wherein the isolated converter is configured for generating an output voltage and an output current on the load from a ripple signal on the secondary side; a processor connected to the secondary side of the transformer and connectable to the load, the processor being configured for capturing an AC voltage of an AC component of the ripple signal and the output current, converting the output current to a process voltage, combining the AC voltage and the process voltage to produce a control voltage, and, based on the control voltage and a preset reference voltage, generating a control signal; at least one coupling element connected to the processor, wherein the coupling element is configured to connect to the primary side and the secondary side of the transformer respectively to transmit the control signal from the secondary side to the primary side; a driver connected to the coupling element and the primary side of the transformer for receiving and amplifying the control signal to generate a digital signal; and an electronic switch connected to the primary side for receiving the digital signal and accordingly changing its ON/OFF state for controlling transmitting the input voltage from the input terminal to the transformer, and for thereby regulating the output voltage and the output current; wherein the electronic switch is further connected to the driver for receiving the digital signal. a transformer comprising a primary side and a secondary side, wherein the primary side is connectable to the input terminal and the secondary side is connectable to a load, wherein the isolated converter is configured for generating an output voltage and an output current on the load from a ripple signal on the secondary side; a processor connected to the secondary side of the transformer and connectable to the load, the processor being configured for capturing an AC voltage of an AC component of the ripple signal and the output current, converting the output current to a process voltage, combining the AC voltage and the process voltage to produce a control voltage, and, based on the control voltage and a preset reference voltage, generating a control signal; at least one coupling element connected to the processor, wherein the coupling element is configured to connect to the primary side and the secondary side of the transformer respectively to transmit the control signal from the secondary side to the primary side; a driver connected to the coupling element and the primary side of the transformer for receiving and amplifying the control signal to generate a digital signal; and an electronic switch connected to the primary side for receiving the digital signal and accordingly changing its ON/OFF state for controlling transmitting the input voltage from the input terminal to the transformer, and for thereby regulating the output voltage and the output current; wherein the electronic switch is further connected to the driver for receiving the digital signal.