LM2575-3.3YN

LM2575-3.3YN Application Field and Working Principle

LM2575-3.3YN, a DC-DC switching regulator, is a monolithic integrated circuit from national semiconductor. The core of the circuit is a buck-type topology, which can provide constant output voltage and maintain short-circuit protection for outside current. It uses an external Schottky diode to control the current flow of the power switching circuit, ensuring high efficiency and regulating external ripple of the output.

LM2575-3.3YN application mainly includes digital products, such as microcomputers, digital cameras, POS machines, printers, digital surveillance systems, handheld barcode scanners, DVD and so on. It is also suitable for industrial control, instrumentation, precision small and medium-sized power supply requirements. The specific application fields are: step-down power supply converting high-voltage DC power to low-voltage DC power, OR-ing power supply, emergency power supply, voltage conversion system, etc.

Working Principle

LM2575 series of DC-DC switching regulator is a buck-type topology, which can provide a constant voltage output and maintain short-circuit protection for the external current. Working mainly has two parts, power switching circuit and power control circuit. The power switching circuit uses oscillator circuit, which is composed of the resistor RT and capacitor CT. By adjusting the resistors RT and RC, the conduction time and the conduction frequency of the buck switch can be adjusted and the output frequency of the operation can be determined. In order to ensure the high efficiency and suppress the external ripple of the output, an external Schottky diode is used to control the current flow of the power switching circuit.

When the output voltage is normal and the output current is below the specified load, the power control circuit will set the output voltage by adjusting the conduction time of the switch. When the output current reaches a certain level, the power control circuit will adjust the conduction time, thereby controlling the output voltage and output power. When the output current increases to the specified upper limit, the switch will be turned off, thus ensuring that the output current will not be too large and the output voltage will remain constant.

Conclusion

The LM2575-3.3YN is an integrated circuit designed for DC-DC switching regulator applications. Its core is a buck-type topology, which can provide a constant output voltage and maintain short-circuit protection for external current. It uses an external Schottky diode to control the current flow of the power switching circuit, ensuring high efficiency and regulating external ripple of the output. Its applications include digital products, industrial control, instrumentation and precision small and medium size power supply.