The SG1845J-883B is a current mode PWM controller designed for off-line isolated switching regulators. It is ideal for a wide range of applications, including flyback, forward, and push-pull converters. The SG1845J-883B offers a number of features that make it an excellent choice for power supply designers, including:

Complete off-line control: The SG1845J-883B includes all of the features needed to implement a complete off-line switching power supply, including undervoltage lockout, overvoltage protection, and current limiting. Low start-up current: The SG1845J-883B has a low start-up current of less than 1mA, making it ideal for battery-powered applications. Automatic feed forward compensation: The SG1845J-883B includes automatic feed forward compensation, which simplifies loop design and improves load regulation. Trimmed oscillator discharge current: The SG1845J-883B has a trimmed oscillator discharge current of less than ±10%, which improves frequency stability. Pulse-by-pulse current limiting: The SG1845J-883B includes pulse-by-pulse current limiting, which protects the power supply from overcurrent conditions. Enhanced load response characteristics: The SG1845J-883B has enhanced load response characteristics, which improve transient response and reduce output ripple. Undervoltage lockout with 6V hysteresis: The SG1845J-883B has undervoltage lockout with 6V hysteresis, which prevents the power supply from turning on until the input voltage is high enough. Double-pulse suppression: The SG1845J-883B includes double-pulse suppression, which prevents the power supply from generating two pulses in a row. High-current totem-pole output (1A peak): The SG1845J-883B has a high-current totem-pole output (1A peak), which can drive a wide range of power MOSFETs. Internally trimmed band-gap reference: The SG1845J-883B has an internally trimmed band-gap reference, which provides accurate and stable voltage regulation. 500kHz operation: The SG1845J-883B operates at a frequency of 500kHz, which allows for the use of smaller components and higher power densities. Low shoot-through current (<75mA over temperature): The SG1845J-883B has a low shoot-through current of less than 75mA over temperature, which improves efficiency and reduces power dissipation. The SG1845J-883B is available in a variety of package options, including 8-pin DIP, 8-pin SOIC, and 10-pin MSOP. It is also available in a military grade version, the SG3845J-883B, which is qualified to MIL-STD-883B.

The SG1845J-883B is a versatile and reliable current mode PWM controller that is ideal for a wide range of off-line switching power supply applications.

Applications

The SG1845J-883B can be used in a wide range of off-line switching power supply applications, including:

Flyback converters Forward converters Push-pull converters AC/DC adapters Open frame power supplies Distributed power supplies Battery chargers Industrial power supplies Communication power supplies Computer power supplies Consumer electronics power supplies Design Considerations

When designing a power supply using the SG1845J-883B, there are a few key considerations that should be kept in mind:

Loop design: The SG1845J-883B is a current mode PWM controller, so the loop design is important for ensuring stability and good performance. The SG1845J-883B includes automatic feed forward compensation, which simplifies loop design. Output capacitor selection: The output capacitor selection is important for ensuring good transient response and low output ripple. The SG1845J-883B can be used with a variety of output capacitor.