STMicroelectronics EVLSRK1004B

Overview

EVLSRK1004B from STMicroelectronics is an evaluation board for the SRK1004B secondary-side synchronous rectification controller, designed specifically for Non-Complementary Active Clamp Flyback (NC-ACF) converters. It integrates the BSC034N10LS5 PowerFLAT 5×6 N-channel MOSFET (100 V, 156 A, 4.5 mΩ @ 4.5 V), supports high-side/low-side configuration, operates up to 500 kHz, and features DVS sensing with 190 V AMR capability.

For engineers reviewing the EVLSRK1004B datasheet, EVLSRK1004B pinout, EVLSRK1004B application, or EVLSRK1004B equivalent, this board enables rapid validation of SRK1004B-controlled synchronous rectification in NC-ACF topologies-particularly where low R_DS(on), fast turn-off delay (150 ns), and robust short-circuit detection are critical for efficiency and reliability in high-density AC/DC adapters and USB PD power supplies.

Technical Context

The EVLSRK1004B implements a zero-current-switching (ZCS)-based control scheme: it turns on the SR MOSFET as soon as reverse body diode conduction begins and turns it off near current zero-crossing. This minimizes conduction loss while avoiding shoot-through in NC-ACF operation.

It supports dual configuration modes via jumper settings: low-side mode (V_CC supplied directly from output voltage) and high-side mode (requires auxiliary winding supply and R5 > 47 kΩ for configurable V_OUT,SC threshold). The board includes integrated DVS sensing, internal gate drive, and fast short-circuit detection logic tied to the SRK1004B's SCP pin.

Key Specifications

Availability

EVLSRK1004B is available at Aetrix Electronics and suitable for high-efficiency AC/DC adapter development, USB PD 3.1 power supply qualification, and industrial flyback-based SMPS design requiring stable component supply and validated reference implementation.

Supply support for EVLSRK1004B 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, Switzerland, specializing in power management, analog, microcontrollers, and automotive-grade ICs.

The SRK1004x family-including the SRK1004B used on EVLSRK1004B-is engineered for secondary-side synchronous rectification in high-frequency flyback converters, targeting >94% efficiency in compact, thermally constrained adapters and chargers.

FAQ

What topology is EVLSRK1004B optimized for?

EVLSRK1004B is specifically configured and validated for Non-Complementary Active Clamp Flyback (NC-ACF) converters. Its layout, component selection (e.g., BSC034N10LS5 MOSFET), and default jumper settings target low-side operation with direct output voltage biasing, though high-side use is supported via auxiliary winding and R5 resistor configuration.

Can EVLSRK1004B be used with Quasi-Resonant (QR) flyback converters?

Yes-EVLSRK1004B evaluates the SRK1004B controller, which supports both NC-ACF and QR flyback topologies per ST's documentation. However, the board's default configuration (e.g., R5 = 22 kΩ) is set for NC-ACF low-side operation; QR use may require layout or component adjustments to match resonant timing and gate-drive timing requirements.

What is the role of R5 on the EVLSRK1004B board?

R5 configures short-circuit detection threshold (V_OUT,SC) for high-side operation: 22 kΩ disables detection (for low-side mode), while ≥47 kΩ enables it. For example, R5 = 150 kΩ sets V_OUT,SC ≈ 2 V, allowing the SRK1004B to inhibit gate drive during output short events when powered from an auxiliary winding.

Is the SRK1004B controller on EVLSRK1004B pin-compatible with other SRK1004x variants?

Yes-the SRK1004A/B/C/D/E/F share identical VFDFPN-6L (2×2 mm) packaging and pinout (VCC, GND, DVS, GD, VO, SCP). Differences lie only in internal gate-drive voltage (logic vs. standard level) and turn-off delay; thus, PCB layout is reusable across variants, but MOSFET selection must match the specific variant's drive capability.