
Fairchild Semiconductor
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 completely shuts off PWM output.
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
VDDOver 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
APPLICATIONs
General-purpose switch-mode power supplies and flyback power converters, including:
Power Adapters
Open-frame SMPS
SMPS with Surge-current Output, such as for Printers, Scanners, Motor Drivers