TOP243G-TL

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The TOP243G-TL is a PWM flyback controller with primary side regulation. It features integrated primary N-channel MOSFET, and incorporates all the necessary control, drive and protection functions under offline topologies for ac-dc power conversion. It is easy to use and does not require external compensation, which simplifies the design process and allows for compact solution. This article will discuss the application field and working principle of the TOP243G-TL.

Application Field

The TOP243G-TL is a general-purpose offline switcher power IC designed for economical and small isolated converters. It can be used for universal input voltage range from 85 VAC to 265 VAC, standard output power up to 12W, and peak-time power up to 24W. It is available in SO-8 and DFN-8 packages, ideal for applications with small board space, such as desktop PCs and LCD TV applications. Its features and functions are also suitable for cost-effective applications such as LED light, phone chargers, battery chargers, and other low-cost power supplies.

Working Principle

The TOP243G-TL utilizes primary side regulation (PSR), which works by providing feedback of the load current to the power switch through an optically isolated sensing and current comparator circuit. Primary regulation simplifies the power supply design by eliminating the need for the traditional secondary side winding, optocoupler and other control circuitry. Additionally, when the power switch is turned on, the internal soft-start circuit slowly increases the switch-bias voltage, thus providing additional protection against inrush current.

The output voltage of the TOP243G-TL is controlled through the power switch\'s duty cycle, which is calculated by the topology\'s threshold voltage and the measured load current. When load increases, the power switch\'s duty cycle is adjusted accordingly in order to regulate the output voltage. When the overload or short circuit conditions occur, the output voltage and current are sensed and then are used by the overload protection circuit to turn off the power switch, protecting it from any potentially hazardous situation.

The TOP243G-TL incorporates a frequency jittering circuit, which introduces diamond-shaped frequency-axial spread to reduce EMI concerns and prevent RF coil saturation. In addition, the frequency jittering allows the user to configure the converter to automatically choose a fixed switching frequency across a wide range of input and output power levels, thus offering high efficiency and excellent performance without requiring additional external components.

The internal fixed frequency oscillator of the TOP243G-TL operates in the range of 26kHz to 300kHz. An external PFM/PWM switch can also be used to select the switching frequency. In addition, the reverse voltage protection circuit and the over-temperature protection circuit are integrated inside the TOP243G-TL, providing highest safety to the device.

Conclusion

The TOP243G-TL is an N-channel MOSFET integrated power switch with primary side regulation (PSR). It is applicable for offline switchers and PMIC - AC DC Converters, suitable for a wide range of cost-effective applications such as phones chargers, battery chargers, LED lights and other low-cost power supplies. The TOP243G-TL provides higher safety to the device with integrated reverse voltage protection and over-temperature protection. Thus it is highly recommended for your power supply design.

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