STMicroelectronics Announces Innovative Synchronous Rectification Controller for High Efficiency and Economical Power Adapters

March 20, 2020, China – STMicroelectronics SRK1001 secondary-side synchronous rectifier controller introduces adaptive capabilities to reduce overall bill of materials, minimize circuit size, and simplify power adapters, chargers, USB Power Delivery ports, and Design of lighting power supply based on flyback topology.

The SRK1001 features a fast turn-on design with minimal delay and an innovative adaptive turn-off logic that minimizes the on-time of the synchronous rectifier MOSFETs, thereby minimizing switching losses and achieving maximum efficiency. Unlike other controllers on the market, the advanced design of the SRK1001 does not require external compensation circuitry to eliminate parasitic inductance effects.

The advantage of synchronous rectification is not obvious at light load, but the SRK1001 can also ensure that the converter has excellent high efficiency performance. When the MOSFET conduction period reaches the minimum set value of the conduction time or detects that the primary side controller enters the burst mode, the SRK1001 automatically enters the low power consumption mode, and the quiescent current is only 160µA.

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

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

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

The SRK1001 is in production now in an 8-pin SO8 package.

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