STMicroelectronics SRK1004BTR

Overview

SRK1004BTR 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 150 ns typ. turn-off delay, 5.5 V internally regulated VCC, 190 V AMR drain-sense capability, and operates up to 500 kHz - enabling high-efficiency, high-power-density USB-PD chargers.

For engineers reviewing the SRK1004BTR datasheet, SRK1004BTR pinout, SRK1004BTR application, or SRK1004BTR equivalent, key selection criteria include turn-off delay matching for MOSFET stray inductance compensation, high-voltage DVS sensing integrity, SCP configuration for short-circuit detection in high-side topology, and compatibility with logic-level or standard-level N-channel MOSFETs in compact DFN 2x2 mm layouts.

Technical Context

The SRK1004BTR implements a dual-threshold, time-blanked zero-current detection scheme: it triggers SR MOSFET turn-on when DVS falls below −330 mV (typ), with 125 ns turn-on enable window, and turn-off when DVS crosses ~0 V after a fixed 150 ns extra delay to compensate for parasitic drain inductance-induced timing advance. Its internal LDO regulates VO (4–36 V) to stable 5.5 V on VCC for gate drive and logic.

It supports two distinct operating modes: in low-side configuration, VO is directly connected to output voltage; in high-side configuration, VO requires an auxiliary winding, and SCP pin enables 3 V output short-circuit detection via external resistor biasing - disabling SR operation when VOUT drops below threshold while maintaining fast recovery above 3.7 V.

Key Specifications

Pinout & Package

SRK1004BTR uses a thermally enhanced DFN-6 (2×2 mm, 0.5 mm pitch) package with exposed pad (EP) connected to GND for optimal PCB-level heat dissipation. Pin 1 (VO) accepts unregulated supply up to 36 V; Pin 6 (DVS) is rated for 190 V absolute max and requires 220 Ω series SMD resistor for ESD and dv/dt protection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SRK1004ATR and SRK1004CTR, SRK1004BTR uniquely balances medium-turn-off delay (150 ns) and 5.5 V VCC to optimize efficiency across mid-range power USB-PD adapters using common logic-level MOSFETs - offering best-in-class trade-off between stray inductance compensation and gate drive strength without overdesign.

Availability

SRK1004BTR is available at Aetrix Electronics and suitable for high-power-density USB-PD adapters/chargers, in-wall smart outlets, and multi-port USB-C docking stations requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for SRK1004BTR 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 SRK1004 product line delivers dedicated synchronous rectification controllers for advanced flyback topologies - specifically engineered to replace diode rectifiers in NC-ACF, resonant, and quasi-resonant converters targeting >94% efficiency and sub-30 mW standby power.

FAQ

What is the purpose of the SCP pin on SRK1004BTR?

The SCP pin provides a 1 V internal reference used to configure output short-circuit protection in high-side configurations. An external resistor from SCP to ground sets a threshold - typically 3 V - below which the IC disables the gate driver. In low-side operation, SCP must be disabled with a 22 kΩ pull-down to avoid false triggering, and UVLO on VO handles fault detection instead.

How does SRK1004BTR compensate for MOSFET drain stray inductance?

SRK1004BTR incorporates a fixed 150 ns extra turn-off delay to counteract the timing advance caused by drain-stray inductance (L_stray/R_DS(on)). This ensures the SR MOSFET remains on until true zero-current crossing, preventing premature turn-off and associated conduction loss degradation - confirmed in DS14372 Rev 3 Table 8 and Section 6.2.2.1.

Can SRK1004BTR operate in both high-side and low-side SR configurations?

Yes - SRK1004BTR supports both configurations. In low-side mode, VO connects directly to the output rail (4–36 V); in high-side mode, VO connects to an auxiliary winding, and SCP enables output short-circuit detection. The datasheet provides separate schematics (Figures 3 and 4) and specifies distinct routing, decoupling, and protection requirements for each.

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

A 220 Ω thick-film 0805 SMD resistor is mandatory between DVS and the SR MOSFET drain. It limits dynamic current injection during fast dv/dt events (e.g., flyback ringing), protects the 190 V AMR-rated pin from overstress, and reduces noise coupling into the sensitive −330 mV turn-on comparator - as specified in Section 6.2 and Figure 2 notes of DS14372 Rev 3.