SG5842JA

The highly integrated SG5842A/JA series of PWM controllers provides several features to enhance the performance of flyback converters. To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency at light-load conditions. To avoid acoustic-noise problem, the minimum PWM frequency set above 22KHz. This green-mode function enables the power supply to meet international power conservation requirements. To further reduce power consumption, SG5842A/JA is manufactured using the BiCMOS process. This allows a low start-up current, around 14?A, and an operating current of only 4mA. As a result, a large start-up resistance can be used.

The SG5842A/JA built-in synchronized slope compensation achieves stable peak-current-mode control.

SG5842JA integrates a frequency hopping function that helps reduce EMI emission of a power supply with minimum line filters.

SG5842A/JA provides many protection functions. In addition to cycle-by-cycle current limiting, the internal open-loop protection circuit ensures safety should an open loop or output short-circuit failure occur. PWM output is disabled until V_DD drops below the UVLO lower limit, then the controller starts again. As long as V_DD exceeds about 24V, the internal OVP circuit is triggered. An external NTC thermistor can be applied for over-temperature protection.

SG5842A/JA is available in an 8-pin DIP or SOP package.