The UCC24630 is recommended as a synchronous rectifier controller in a wide variety of flyback power supplies. It is compatible with Discontinuous Conduction Mode (DCM) and Transition Mode (TM) controllers in fixed frequency or variable frequency applications. It is compatible with Continuous Conduction Mode (CCM) controllers in fixed frequency applications.

It is suitable as a synchronous rectifier for flyback power supplies with an input of 85 V_AC to 265 V_AC and an output from 5 V to 24 V. It can also be used in other flyback applications with different input and/or output voltages. But be sure all voltages and currents are within the recommended operating conditions and absolute ratings of the device.

It is compatible with flyback converters operating at the transition mode limit, at low line, with switching frequencies as low as 40 kHz. It may also be used in switching speeds up to 200 kHz.

The VDD operating range allows direct connection to converter outputs from 5 V to 24 V. Since the driver and control share the same VDD and ground, it is recommended to place a good quality ceramic capacitor as close as possible to VDD and GND pins. To reduce VDD noise and eliminate high-frequency ripple current injected from the converter output, it is recommended to place a small resistance of 2.2 Ω to 10 Ω between the converter output and VDD. The device can tolerate VDD rise times from 100 µs to very long rise times typical of constant current chargers. The start-up sequence will always be as shown in Figure 13. VDD can be connected to an external bias to extend the device's operating range below 3.5 V or above 24-V converter outputs.