Synchronous rectifier controller for efficient and economical power adapters

     The SRK1001 uses a fast on-off design with minimal delay and introduces an innovative adaptive off logic to minimize on-off times for synchronous rectified MOSFETs, thereby minimizing switching losses and achieving maximum efficiency. Unlike other controllers on the market, the SRK1001 advanced design eliminates the need for an external compensation circuit to eliminate parasitic inductance effects.

     Synchronous rectification is not an obvious advantage at light loads, but the SRK1001 also guarantees excellent high efficiency performance of the converter. When the MOSFET on-period reaches the minimum on-time setting or when the primary controller is detected to enter burst mode, the SRK1001 automatically enters low-power mode with a static current of only 160µA.

     Versatility is another advantage of the SRK1001, which can be used in quasi-resonant (QR) converters and supports continuous/discontinuous current mode (CCM/DCM) fixed frequency operating modes up to 300kHz. The blanking time after switching on and off can be set to prevent noise from causing stray behavior and ensure the stability of the controller.

     The SRK1001 supports a wide input voltage of 4.5V-32V, especially for applications with output voltages up to 24V, and is able to keep the voltage regulated to a minimum 2V output in CCM mode. N channel synchronous rectifier MOSFET drive capability, maximum sink current up to 1A, maximum source current up to 0.6A.

     The SRK1001 controller chip provides a dedicated disable/sync pin for turning off synchronized MOSFETs and remotely triggering low power mode, or synchronizing MOSFETs off in CCM operating mode. There is also a drain voltage detection input pin on the chip, which can monitor the drain to source voltage of the external MOSFET, up to 185V detection voltage.