STMicroelectronics, Inc. AC DC Converters, Offline Switches L5991

The L5991 is a primary controller integrated circuit designed for offline AC-DC power supply applications, utilizing a fixed frequency current mode control with a maximum switching frequency of up to 1 MHz. It features low start-up current consumption of less than 120 mA and is capable of driving high-current outputs suitable for power MOSFETs, with a peak output current of 1.5 A. Key functionalities include programmable soft start, standby operation for reduced frequency during light load conditions, and precise maximum duty cycle control with limits of 100% and 50%. The device also incorporates overcurrent protection with a restart delay, pulse-by-pulse current limiting, and internal leading edge blanking for current sensing. The L5991 is available in both DIP16 and SO16 packages, making it versatile for various design requirements. Engineers considering this product should note its operational temperature range of -40 to 150 ¬8C and its thermal resistance characteristics, which are 80 ¬8C/W for the DIP16 package and 120 ¬8C/W for the SO16 package.