STMicroelectronics SRK1001 synchronous-rectification controller

Click2Contact

The STMicroelectronics SRK1001 secondary-side synchronous-rectification controller introduces adaptive features designed to cut bill-of-materials costs, minimise circuit size and simplify the design of power adapters, chargers, USB power delivery outlets and lighting power supplies based on flyback topologies.

Designed for fast turn-on with minimum delay, and introducing innovative adaptive turn-off logic, the product maximises synchronous-rectification MOSFET conduction time for optimum efficiency with minimal switching losses. Unlike other controllers, its design requires no external compensation circuitry to eliminate parasitic-inductance effects.

The product also offers good converter efficiency at light loads, where synchronous rectification is no longer beneficial. The device automatically enters low-consumption mode when the MOSFET conduction period reaches the programmed minimum on time or when burst-mode operation of the primary controller is detected. The quiescent current in this mode is just 160 µA.

Versatility is another strength of the device, allowing use in quasi-resonant (QR) converters and mixed continuous/discontinuous current mode (CCM/DCM) fixed-frequency operation at up to 300 kHz. Robustness is assured, with programmable blanking time after both turn-on and turn-off to prevent noise from inducing spurious behaviour.

Suitable for applications with output voltage up to 24 V, and capable of maintaining regulation down to 2 V output in CCM, the product has a wide supply-voltage range of 4.5 to 32 V. The output can sink up to 1 A and source up to 0.6 A to control the gate of the external N-channel synchronous-rectification MOSFET.

A dedicated Disable/Synchronization pin is provided to turn off the synchronous MOSFET and remotely trigger low-consumption mode, or to synchronise MOSFET turn-off during CCM operation. There is also drain-voltage sensing input capable of monitoring the external MOSFET drain-source voltage up to 185 V.

For more information: www.st.com/srk1001-pr.