STMicroelectronics Launches High Energy Efficiency Flyback Converter Secondary Synchronous Rectifier Chips SRK1000A and SRK1000B

STMicroelectronics has launched flyback converter secondary synchronous rectification (SR) chips SRK1000A and SRK1000B, featuring high energy efficiency and low power consumption. This product series now includes a more cost-effective and smaller package that can be used for chargers, fast chargers, adapters, and USB PD ports.

These two devices adopt the minimum delay fast on design and innovative adaptive turn off technology, which can maximize the on time of synchronous rectification MOSFET without adding external components, and minimize the parasitic inductance effect in the circuit, thus greatly improving the energy efficiency of the circuit system and significantly reducing the cost of the bill of materials.

Both SRK1000A and SRK1000B products can be used for various flyback controllers, including quasi resonant (QR) and CCM/DCM hybrid mode flyback topologies with a fixed frequency up to 300kHz, simplifying system design. Both devices can set the blanking time after conduction (TON) by selecting resistors to prevent noise from causing stray issues. The blanking time after SRK1000A shutdown (TOFF) is fixed at 2 μ s. SRK1000B is 3 μ s。

Both devices have a light load, low-power, and power-saving mode. When synchronous rectification is no longer needed, the controller enters a low-power sleep mode. The implementation method is to detect whether the primary controller enters burst mode or whether the conduction time of the synchronous rectification MOSFET transistor is lower than the TON minimum preset value. Controller low-power mode static current is only 160 μ A。

SRK1000A and SRK1000B are suitable for output voltages up to 19V, capable of maintaining stable output to 2V in CCM mode, supporting 4.5V-32V wide voltage power supply, and rated drain source voltage of 100V. The output current is up to 1A, with a maximum pulling current of 0.6A, used to control the gate of external N-channel synchronous rectification MOSFET tubes.

Both SRK1000A and SRK1000B are packaged in a 2.9mm x 2.8mm 6-pin SOT23-6L package.

STMicroelectronics

STMicroelectronics is a global independent semiconductor company and is a leader in developing and delivering semiconductor solutions across the spectrum of microelectronics applications. An unrivaled combination of silicon and system expertise, manufacturing strength, Intellectual Property (IP) portfolio and strategic partners positions the Company at the forefront of System-on-Chip (SoC) technology and its products play a key role in enabling today's convergence trends.