UCC287502DBVR

The UCC28750 is a highly integrated, current-mode PWM controller with continuous conduction capability, optimized for high-performance, low standby power, and cost-effective offline flyback converter applications using an optocoupler. Under light-load conditions, the device enters frequency foldback and burst mode to improve light-load efficiency. The burst mode algorithm used in the UCC28750 controls the minimum effective switching frequency to prevent audible noise under light-load conditions. Frequency dithering improves EMI performance and is active during normal, frequency foldback, and power boost operations. The UCC28750 offers protection features that enable robust converter designs with minimal external components. Output over-power protection (OPP) and cycle-by-cycle overcurrent limiting protect the load and power stage components from electrical stress. Overvoltage and undervoltage lockout (OVLO and UVLO) prevent switching operation under undesired input conditions. Depending on the device variant, the FLT pin provides line undervoltage detection and protection, or external overtemperature and overvoltage protection. Regardless of device variant, the FLT pin also allows the device to be disabled via external control by pulling the pin to ground potential.

Applications

• Isolated offline AC/DC power supplies
• Appliances:
• Battery packs and chargers
• Small household appliances
• Large appliances
• Grid infrastructure:
• Smart meters
• String inverters
• Microinverters
• Power delivery:
• Server power supplies with 12V output

Key features

• Stable CCM operation with internal slope compensation
• Fixed-frequency operation at 65kHz or 100kHz
• Secondary-side regulation (SSR) with optocoupler
• Frequency foldback and burst mode for improved light-load efficiency
• Frequency dithering for improved EMI performance
• Gate source/sink current capability: 300mA/500mA
• Internal 4ms soft-start
• Robust protection features:
• Over-voltage and under-voltage lockout
• Output over-power protection (OPP)
• Output short-circuit (OSC) protection
• Output over-voltage protection (OVP)
• Cycle-by-cycle peak over-current limiting
• External over-temperature, over-voltage protection (OTP, OVP) and under-voltage detection via FLT pin
• Internal thermal shutdown