SG6846B Datasheet | Fairchild Semiconductor

SG6846B - Highly Integrated Green-Mode PWM Controller .. October 2008 SG6846B Highly Integrated Green-Mode PWM Controller Features - - - - - - - - - - - - Low Startup Current: 8µA Low Operating Current: 3.7mA Peak-Current Mode Operation with Cycle-by-cycle Current Limiting PWM Frequency Continuously Decreasing with Burst Mode at Light Loads VDD Over Voltage Protection (OVP) AC Input Brownout Protection with Hysteresis Constant Output Power Limit (Full AC Input Range) Internal Latch Circuit for OVP, OTP, and OCP (BLSY, BLSZ) Two-level OCP Delay with 200ms Programmable PWM Frequency with Frequency Hopping OCP Threshold is 2/3 Peak Current Limit Soft Startup Time: 5ms Description The highly integrated PWM controller, SG6846B, provides several Features to enhance the performance of fly-back converters. To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Under zero-load conditions, the power supply enters burst-mode. This pletely shuts off PWM output. If VFB is larger than around 1.6V, PWM pulses out. This green-mode function enables power supplies to meet international power conservation requirements. The SG6846B is designed for SMPS with surge-current output. It is incorporated with a two-level OCP function. Besides, the cycle-by-cycle current limiting, if the switching current is higher than OCP threshold and lasts for 200ms, SG6846B stops gate immediately and latches itself (BLSY version) or restarts after VDD charges up to 16.5V (BCSY version). SG6846B also integrates frequency-hopping function internally. The frequency hopping function helps reduce EMI emission of a power supply with minimum line filters. It has...