STMicroelectronics EVLSRK1000-TO

Overview

EVLSRK1000-TO from STMicroelectronics is a demonstration board for the SRK1000 adaptive synchronous rectification controller, designed to replace secondary-side diodes in flyback converters. It integrates the STF80N10F7 100 V / 10 mΩ N-channel MOSFET in TO220FP package, supports up to 500 kHz switching, operates from 3.5 V to 32 V VCC, and features fixed turn-on with adaptive turn-off timing.

For engineers reviewing the EVLSRK1000-TO datasheet, EVLSRK1000-TO pinout, EVLSRK1000-TO application, or EVLSRK1000-TO equivalent, this board enables rapid evaluation of QR and FF flyback topologies with integrated gate drive, DVS-rated up to 90 V, and configurable blanking via R5 (68 kΩ) and optional C4 (100 pF).

Technical Context

The EVLSRK1000-TO implements ST's SRK1000 IC, which uses a dedicated control scheme for secondary-side synchronous rectification in flyback converters. It delivers high-current gate drive for external N-channel MOSFETs and supports both quasi-resonant (QR) and fixed-frequency (FF) mixed DCM-CCM operation modes.

Board-level configuration includes factory-set QR mode, with FF mode enabled by adding a 100 pF capacitor at C4. The TON pin is biased with a 68 kΩ resistor (R5), setting blanking time to ~0.8 μs - critical for noise immunity during voltage sensing at the drain node.

Key Specifications

Availability

EVLSRK1000-TO is available at Aetrix Electronics and suitable for flyback AC-DC adapters, USB PD power supplies, and industrial offline SMPS requiring stable component supply and fast SR evaluation capability.

Supply support for EVLSRK1000-TO includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, delivering microcontrollers, power ICs, analog devices, and silicon solutions for industrial, automotive, and consumer applications.

The SRK1000 product line targets high-efficiency secondary-side synchronous rectification in isolated flyback converters, specifically optimizing light-load efficiency and EMI performance through adaptive timing control.

FAQ

What topology does the EVLSRK1000-TO support?

This board is configured for quasi-resonant (QR) flyback operation out-of-the-box. Fixed-frequency (FF) flyback operation is supported by adding a 100 pF capacitor at position C4. Both modes leverage the SRK1000's adaptive turn-off to maintain ZCD accuracy across variable operating conditions.

Can the EVLSRK1000-TO be used without modifying an existing flyback design?

Yes - it is designed as a drop-in replacement for secondary-side rectifier diodes. The board connects directly across the secondary winding and drives the integrated STF80N10F7 MOSFET. No primary-side changes are required, though auxiliary winding voltage must meet the 3.5–32 V VCC range.

What is the purpose of R5 on the TON pin?

R5 (68 kΩ) sets the blanking time to approximately 0.8 μs after turn-on, preventing false zero-current detection during drain voltage ringing. This ensures robust operation under high dv/dt conditions typical in QR flyback converters.

Is the STF80N10F7 MOSFET replaceable on the board?

No - the STF80N10F7 is soldered in TO220FP package and not socketed. Its 100 V rating and 10 mΩ R_DS(on) are optimized for the SRK1000's drive strength and the board's thermal layout. Replacement requires rework and validation of gate drive timing and thermal performance.