STMicroelectronics STEF4SPUR

Overview

STEF4SPUR from STMicroelectronics is an integrated electronic fuse (e-fuse) designed for series protection of 3.3 V and 5 V power rails. It provides overcurrent limiting (5 A trip, 3 A short-circuit clamp), output voltage clamping (3.8 V / 5.7 V), controlled soft-start (0.6–30 ms), and thermal auto-retry shutdown. Its DFN 3x3 10L package enables compact placement in high-density storage and consumer power management circuits.

For engineers reviewing the STEF4SPUR datasheet, STEF4SPUR pinout, STEF4SPUR application, or STEF4SPUR equivalent, key selection considerations include mode-selectable UVLO thresholds (2.3 V / 3.6 V), R_DS(on) of 40 mΩ (typ.), foldback current limiting, and GND-connected exposed pad thermal performance - all critical for SSD, HDD, and set-top box power rail integrity.

Technical Context

The STEF4SPUR implements a monolithic N-channel power MOSFET with integrated sensing FET, current-limiting control loop, and dual-mode voltage clamp circuitry. Its VCP pin selects between two independent UVLO and clamping thresholds - 2.3 V/3.8 V for 3.3 V systems and 3.6 V/5.7 V for 5 V systems - enabling single-part flexibility across common logic supply domains.

Thermal protection uses a 140 °C shutdown threshold with 20 °C hysteresis and automatic retry, while soft-start timing is externally adjustable via CSS capacitor (0.6 ms to 30 ms). The device operates from -40 °C to 85 °C ambient, with R_thJA = 40 °C/W and R_thJC = 2.5 °C/W for board-level thermal design.

Key Specifications

Pinout & Package

STEF4SPUR is housed in a thermally enhanced DFN 3x3 10L package with exposed pad (internally connected to GND) for low R_thJC (2.5 °C/W) and improved power dissipation handling.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar electronic fuse applications.

Compared with TCKE805A and TPS25940A, STEF4SPUR offers unique hardware-configurable 3.3 V/5 V operation, analog soft-start tuning, and lower bias current (65 µA), making it optimal for fixed-function, space-constrained storage and consumer power rails where simplicity and thermal resilience are prioritized.

Availability

STEF4SPUR is available at Aetrix Electronics and suitable for hard disk drives, solid state drives, and set-top boxes requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for STEF4SPUR 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, automotive ICs, and industrial microcontrollers.

The STEF4SPUR belongs to ST's eFuse portfolio, engineered specifically for high-reliability, low-footprint overcurrent and overvoltage protection in storage subsystems and consumer electronics power distribution networks.

FAQ

What is the maximum continuous input voltage STEF4SPUR can withstand?

The absolute maximum VIN rating is 15 V, but the device is specified for operation up to 10 V in normal use. Exceeding 10 V risks triggering the voltage clamp continuously and may accelerate thermal stress. For sustained 12 V input, external pre-regulation or alternative protection architecture is recommended.

How does the VCP pin determine operating mode, and what happens if left floating?

VCP must be actively driven: ≥2 V selects 5 V mode (3.6 V UVLO, 5.7 V clamp); ≤0.4 V selects 3.3 V mode (2.3 V UVLO, 3.8 V clamp). If floating, VCP may settle near mid-supply due to internal leakage, causing undefined behavior - including unstable UVLO or incorrect clamping - and is strictly prohibited per datasheet guidelines.

Can STEF4SPUR be used in parallel for higher current capacity?

No. The device lacks current-sharing features such as matched R_DS(on) or external sync inputs. Parallel operation risks thermal runaway due to mismatched turn-on characteristics and unbalanced current distribution. For >5 A applications, select a higher-rated e-fuse or implement discrete current-sharing design.

What is the role of the exposed pad, and must it be soldered?

The exposed pad is internally connected to GND and serves as the primary thermal conduction path. It must be soldered to a minimum 100 mm² PCB copper pour with ≥4 thermal vias to achieve rated R_thJA = 40 °C/W. Leaving it unsoldered degrades thermal performance by >50%, risking premature thermal shutdown under load.