The figure shows the 4W/5V switching regulator circuit. The circuit adopts TOPSwitch series T0P100 device. TOPSwitch (Three TerminalOffline PWMSwtich) series devices are three-terminal PWM switching power supply. It is characterized in that the PWM controller and MOSFET power switch tube in the high-frequency switching power supply are integrated on the same chip. A two-in-one device. This greatly simplifies the circuit design, improves reliability, and makes the design of the power supply simpler and faster. TOPSwitch devices are available in a variety of packages, in DiP-8 and SMD-8 packages, with four empty feet in the middle, which can be connected to the copper foil of the printed circuit board to transfer the heat generated by the chip directly to the printed circuit board. On the circuit board, there is no need to install a separate heat sink, which saves costs.
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