STMicroelectronics SRK1004CTR

Overview

SRK1004CTR from STMicroelectronics is a secondary-side synchronous rectification controller optimized for Non-Complementary Actively Clamped Flyback (NC-ACF) converters, supporting both high-side and low-side SR MOSFET configurations. It features 9.0 V internally regulated VCC, 25 ns typ. extra turn-off delay, 125 ns typ. turn-on enable window, and operates up to 500 kHz with 190 V AMR drain-sense capability - deployed in high-power-density USB-PD wall-plug adapters.

For engineers reviewing the SRK1004CTR datasheet, SRK1004CTR pinout, SRK1004CTR application, or SRK1004CTR equivalent, key selection criteria include its dual-configurability (HS/LS), logic/standard-level MOSFET support, 25 ns turn-off delay variant, SCP pin short-circuit detection in HS mode, and DFN 6L 2×2 mm thermal performance under burst-mode and CCM-DCM boundary operation.

Technical Context

The SRK1004CTR implements a voltage-sensing zero-current-detection scheme using the DVS pin to monitor SR MOSFET drain-source voltage, triggering turn-on when VDS falls below –330 mV (typ.) and turn-off near 0 V with 25 ns internal extra delay to compensate for stray inductance-induced timing advance. Its control logic distinguishes TDEM (demagnetization) from TREV (reverse current) intervals in NC-ACF topologies to gate only during useful conduction.

It integrates a 9.0 V linear regulator (VCC) fed from VO (4–36 V), delivers 0.6 A peak source / 1.7 A peak sink gate drive, and includes dedicated SCP pin circuitry for fast short-circuit response in high-side configuration - with UVLO-based fallback protection in low-side mode when SCP is disabled via 22 kΩ-to-GND resistor.

Key Specifications

Pinout & Package

Tiny DFN 6L 2×2 mm package with exposed thermal pad (EP), rated for 125 °C junction temperature and optimized for high-density USB-PD adapter PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous rectification controller applications.

Compared with SRK1004BTR and MP6908AGS-Z, SRK1004CTR offers higher VCC headroom for wide-output-range USB-PD, precise 25 ns delay for fast GaN-compatible MOSFETs, and SCP-enabled HS operation - making it optimal for next-gen compact, high-efficiency NC-ACF adapters demanding full safety and thermal headroom.

Availability

SRK1004CTR is available at Aetrix Electronics and suitable for high-power-density USB-PD adapters/chargers, in-wall smart outlets, and GaN-based multi-port laptop chargers requiring stable component supply and long-term lifecycle assurance.

Supply support for SRK1004CTR 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The SRK series targets high-efficiency AC-DC secondary-side control, specifically engineered for NC-ACF, QR, and resonant flyback topologies in ultra-compact USB-PD and energy-efficient power supplies.

FAQ

What is the purpose of the SCP pin on SRK1004CTR?

The SCP (Short-Circuit Protection) pin provides a 1 V reference used with an external 200 kΩ resistor to ground, setting a ~3 V output voltage threshold. When output voltage drops below this level in high-side configuration, the SR MOSFET is immediately disabled - preventing latch-up and thermal runaway during sustained short-circuit events. In low-side mode, SCP is disabled by connecting 22 kΩ to GND, and protection relies on VO UVLO.

Can SRK1004CTR drive standard-level MOSFETs in high-side configuration?

Yes - SRK1004CTR supports both logic-level (V_GS(th) ≤ 2.5 V) and standard-level (V_GS(th) ≈ 4 V) N-channel MOSFETs in either high-side or low-side configuration. Its 9.0 V VCC and 0.6 A peak source current ensure robust gate drive for standard-level devices, while the GD pin's V_GDHigh clamping to VCC prevents overdrive.

How does the 25 ns turn-off delay improve efficiency in NC-ACF converters?

The 25 ns extra turn-off delay compensates for timing advance caused by SR MOSFET drain stray inductance (L_stray), which shifts the sensed VDS zero-crossing earlier than actual current zero. By delaying turn-off, SRK1004CTR ensures the MOSFET remains on until true current zero, minimizing residual body-diode conduction time and reducing conduction loss - especially critical in high-frequency, high-power NC-ACF designs.

What is the minimum recommended DVS series resistor value and why?

A 220 Ω SMD 0805 thick-film resistor is mandatory between DVS and SR MOSFET drain. This limits dynamic current injection during fast dV/dt transitions, protects the internal comparator from ESD-like stress, and ensures reliable operation under worst-case flyback ringing. Using two 0603 resistors in series is preferred for improved power derating and voltage margin in 100 W+ designs.