onsemi SG6846ALSZ

The highly integrated SG6846A series of PWM controllers provides 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 under light - load conditions. Under zero - load conditions, the power supply enters burst - mode. The SG6846A is especially designed for SMPS with surge - current output, incorporated with a two - level OCP function. Besides the cycle - by - cycle current limiting, if the switching current is higher than two thirds the peak - current threshold for 1700ms, over - current protection is activated and the SG6846A latches off. If the switching current is higher than two thirds the peak - current threshold for 100ms and the voltage on the VDD pin is higher than VDD - OFF + 1V, the PWM pulses are latched off immediately once VDD voltage is lower than VDD - OFF + 1V; useful if an output short - circuit occurs. SG6846A also integrates a frequency hopping function that reduces EMI emission of a power supply with minimum line filters. Its built - in synchronized slope compensation provides proprietary internal compensation for constant output power limit over a universal AC input range. Also, the gate output is clamped at 18V to protect the external MOSFET from over - voltage damage. Internal soft - start is built - in to reduce stress on the MOSFET and start - up current during power - on period. Other protection functions include: AC input brownout protection with hysteresis, VDD over - voltage protection, and over - temperature protection. For over - temperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When OCP, VDD OVP, or OTP are activated, an internal latch circuit is used to latch - off the controller. The PWM pulses stay latched off until the power supply is unplugged from the main outlet. SG6846A is available in an 8 - pin SOP package.

• Two - level OCP with 1700ms delay time
• Output short - circuited delay time: 100ms
• Low start - up current (8μA)
• Low operating current (3.7mA)
• Peak - current mode operation with cycle - by - cycle current limiting
• Programmable PWM frequency with frequency hopping
• PWM frequency continuously decreasing with burst mode at light loads
• VDD over - voltage protection (OVP)
• AC input brownout protection with hysteresis and constant output power limit
• Constant output power limit (full AC input range)
• Internal latch circuit for OVP, OTP, and OCP
• Built - in soft - start
• Open - loop protection with 1700ms delay time

• General - purpose switch - mode power supplies and flyback power converters
• Power adapters
• Open - frame SMPS
• Specifically fit for SMPS with surge - current output (such as for printers, scanners, motor drivers, etc.)