SG6846B Highly Integrated Green-Mode PWM Controller October 2008 SG6846B Highly Integrated Green-Mode PWM Controller Features Description The highly integrated PWM controller, SG6846B, Low Startup Current: 8A provides several features to enhance the performance Low Operating Current: 3.7mA of fly-back converters. To minimize standby power consumption, a proprietary green-mode function Peak-Current Mode Operation with Cycle-by-cycle provides off-time modulation to continuously decrease Current Limiting the switching frequency under light-load conditions. PWM Frequency Continuously Decreasing with Under zero-load conditions, the power supply enters Burst Mode at Light Loads burst-mode. This completely shuts off PWM output. If V is larger than around 1.6V, PWM pulses out. This FB V Over Voltage Protection (OVP) DD green-mode function enables power supplies to meet AC Input Brownout Protection with Hysteresis international power conservation requirements. Constant Output Power Limit (Full AC Input Range) The SG6846B is designed for SMPS with surge-current output. It is incorporated with a two-level OCP function. Internal Latch Circuit for OVP, OTP, and OCP Besides, the cycle-by-cycle current limiting, if the (BLSY, BLSZ) switching current is higher than OCP threshold and Two-level OCP Delay with 200ms lasts for 200ms, SG6846B stops gate immediately and latches itself (BLSY version) or restarts after V DD Programmable PWM Frequency with Frequency charges up to 16.5V (BCSY version). SG6846B also Hopping integrates frequency-hopping function internally. The OCP Threshold is 2/3 Peak Current Limit frequency hopping function helps reduce EMI emission of a power supply with minimum line filters. It has built- Soft Startup Time: 5ms in synchronized slope compensation, proprietary internal compensation for constant output power limit over universal AC input range. The gate output is Applications clamped at 18V to protect the external MOSFET from General-purpose switch-mode power supplies and over-voltage damage. flyback power converters, including: Protection include: AC input brownout protection with hysteresis and V over-voltage protection. For over- DD Power Adapters temperature protection, an external NTC thermistor can Open-frame SMPS be applied to sense the ambient temperature. When OCP, V OVP, or OTP are activated, an internal latch DD SMPS with Surge-current Output, such as for circuit is used to latch-off the controller. The latch resets Printers, Scanners, Motor Drivers when V supply is removed. DD SG6846B is available in 8-pin SOP package. Ordering Information Part Operating OCP Packing Eco Package Number Temperature Range Latch Method Status SG6846BLSY -40 to +105C Yes Green 8-Pin Small Outline Package (SOP) Tape & Reel SG6846BLSZ -40 to +105C Yes RoHS 8-Pin Small Outline Package (SOP) Tape & Reel SG6846BCSY -40 to +105C No Green 8-Pin Small Outline Package (SOP) Tape & Reel SG6846BCSZ -40 to +105C No RoHS 8-Pin Small Outline Package (SOP) Tape & Reel For Fairchilds definition of green Eco Status, please visit: SG6846B Highly Integrated Green-Mode PWM Controller Typical Application L EMI AC input VO+ Filter + + N VO- + + 7 3 VIN VDD GATE 8 4 6 RI SENSE 2 FB GND RT 5 1 SG6846B Figure 1. Typical Application Block Diagram 4 0.9V/0.7V VDD VIN 3 Soft Over Power Compersation Driver 8 GATE 0.895-0.065 XVIN Green Q S OSC VDD-TH-G Mode R 7 Internal VDD 6.2V BIAS UVLO 3R 2 FB + 16.5V/10.5V 1R Latch Slope Compensation Blanking SENSE 6 Circuit 1R 2R Debounce 23.6V SCP IRT Delay RT 5 OTP Delay OCP Delay 1.05V 1.15V 1 GND Figure 2. Block Diagram 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com SG6846B Rev. 1.3.4 2