SG6846B

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. If V_FB 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 V_DD 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 built-in synchronized slope compensation, proprietary internal compensation for constant output power limit over universal AC input range. The gate output is clamped at 18V to protect the external MOSFET from over-voltage damage.

Protection of SG6846B  include : AC input brownout protection with hysteresis and V_DD over-voltage protection. For over-temperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When OCP, V_DD OVP, or OTP are activated, an internal latch circuit is used to latch-off the controller. The latch resets when V_DD supply is removed.

SG6846B is available in an 8-pin SOP package.