Offline flyback switch in the CoolSET family
The ICE3RBR1765JGXUMA1 is an integrated offline flyback switcher from Infineon's CoolSET series, combining a 650 V avalanche-rated MOSFET with a PWM controller in a single 16-SOIC package with 12 leads. Designed for isolated AC-DC converter topologies, it delivers up to 41.5 W of output power at a fixed 65 kHz switching frequency, with a 75% maximum duty cycle.
Breakdown voltage and protection suite
The 650 V breakdown rating on the integrated MOSFET gives adequate margin for universal-input flyback designs (85–265 VAC) where reflected voltage plus leakage spike can reach 550–600 V. At a 125 °C junction temperature, the avalanche energy capability must be derated per the SOA curve. On-chip fault protection covers current limiting, over-load, over-temperature, and over-voltage — the controller latches off or auto-restarts depending on the fault type, eliminating the need for external sense resistors or a separate supervisor IC.
Package and thermal integration
The 0.154-inch body width fits a standard SOIC footprint, but the pad clearance and via pattern under the package determine the junction-to-ambient thermal resistance.
Supply voltage and start-up behaviour
The controller operates from a Vcc range of 10.5 V to 25 V, with a start-up threshold of 18 V. This allows the IC to be powered from an auxiliary winding after start-up while the initial charge comes from a high-voltage start-up resistor — a common scheme in flyback supplies to minimise standby losses.