News
STMicroelectronics reveals flexible synchronous rectifier for efficient silicon or GaN converters
29/02/2024Helps simplify operation and save energy in industrial power supplies, portable-device chargers, and AC/DC adapters
STMicroelectronics’ SRK1004 synchronous-rectifier controller eases the design and enhances the efficiency of converters built with silicon or GaN transistors, including industrial power supplies, portable-device chargers, and AC/DC adapters.
Capable of withstanding up to 190V at its sense input, the SRK1004 can be connected in a high-side or low-side configuration. Four variants let users avoid complex calculations by optimizing their design through device selection alone, selecting gate-drive voltage between 5.5V or 9V, with logic-level MOSFETs, standard MOSFETs, or GaN transistors. Suitable for noncomplementary active clamp, resonant, and quasi-resonant (QR) flyback topologies, the SRK1004 introduces a next-generation turn-off algorithm that simplifies operation and saves energy.
The features of this controller enable converters to provide a high output power rating within compact dimensions. The operating frequency can be up to 500kHz, allowing the use of small magnetic components as well as maximizing the benefits of wide-bandgap technology when using GaN transistors. The controller is fabricated in ST’s silicon-on-insulator (SOI) process, which ensures robust performance while permitting a tiny 2mm x 2mm DFN-6L package.
By operating with a supply voltage from 4V to 36V, the SRK1004 can be powered from a variety of standard industrial bus voltages. The wide input-voltage range also provides flexibility to adjust the step-down ratio for optimum efficiency. Also, with fast-acting short-circuit detection built-in, the controller helps build rugged and reliable equipment.
Of the four variants introduced, the SRK1004A and SRK1004B are configured for 5.5V gate-drive voltage and can be used with logic-level MOSFETs or GaN transistors. The SRK1004C and SRK1004D for 9V gate-drive voltage are suited to MOSFETs designed for standard gate-drive signals.
All variants of the SRK1004x synchronous rectification controllers are in production now and available from $0.45 for orders of 1000 units. The evaluation boards, EVLSRK1004A, EVLSRK1004B, EVLSRK1004C, and EVLSRK1004D, are also available to accelerate evaluation and design start with each type, at the budgetary price of $50.00.
SRK1004 controller is intended for secondary side synchronous rectification (SR) in Non-Complementary Actively Clamped Flyback, Resonant Flyback, and Quasi-Resonant Flyback converters.
It provides a gate-drive output suitable for N-channel logic-level or standard level power MOSFETs.
The control scheme of this device is such that the SR MOSFET is switched on as soon as current starts flowing through its body diode and it is then switched off as current approaches zero.
The device can be supplied directly from the converter’s output voltage when operated in low-side configuration. When used in high-side configuration, it is recommended to power the IC from a dedicated auxiliary winding.
When operated in high-side configuration, a special function enables a quick detection of short-circuit conditions to inhibit its operation as if the IC were powered directly from the output voltage.
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All features
- Secondary-side synchronous rectification controller optimized for Non-Complementary Actively Clamped Flyback converter (NC-ACF).
- Able to operate in both low-side and high-side configuration
- Supporting logic level (A and B) and standard level (C and D) MOSFETs
- Two different turn-off delays available to cover a wide range of MOSFETs
- Wide range supply voltage: 4 to 36 V
- Very low operating current (580 µA) and quiescent current (230 µA)
- High-voltage sensing input for SR MOSFET drain-source voltage (190 V AMR)
- Operating frequency up to 500 kHz
- Fast short-circuit detector
- Tiny DFN 6L 2×2 mm package
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