The STMicroelectronics SRK1001 controller is designed for secondary side synchronous rectification (SR) in flyback converters, suitable for operation in QR and mixed CCM/DCM fixed-frequency operation at up to 300kHz.
The SRK1001 features programmable blanking time after both turn-on and turn-off to prevent noise from inducing spurious behavior, designed for fast turn-on with minimum delay and turn-off logic. The controller features synchronous-rectification MOSFET conduction time with minimal switching losses. The SRK1001 requires no external compensation circuitry to eliminate parasitic-inductance effects.
The SRK1001 also ensures 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 160µA.
The controller is suitable for applications with output voltage up to 24V, and maintains regulation down to 2V output in CCM, the SRK1001 has a supply-voltage range of 4.5V to 32V. The output can sink up to 1A and source up to 0.6A 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 synchronize MOSFET turn-off during CCM operation. There is also drain-voltage sensing input capable of monitoring the external MOSFET drain-source voltage up to 185V.
The SRK1001 is in production now, packaged as an 8-pin SO8 device, from $0.33 for orders of 1000 pieces.
For more information, visit www.st.com/srk1001-pr.
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