STMicroelectronics STEF12EPUR

Overview

STEF12EPUR from STMicroelectronics is a 12 V electronic fuse (eFuse) with integrated N-channel power MOSFET, designed for series protection of 12 V power rails in storage and consumer electronics. It delivers 3.6 A continuous current, 53 mΩ typical on-resistance, 15 V output clamping, and thermal latch at 165 °C - enabling robust overcurrent, overvoltage, and thermal fault management in HDD/SSD power paths.

For engineers reviewing the STEF12EPUR datasheet, STEF12EPUR pinout, STEF12EPUR application, or STEF12EPUR equivalent, key selection criteria include programmable current limit via external resistor, controlled dv/dt ramp-up (0.9 ms typ), tri-state Enable/Fault signaling, UL2367 recognition, and DFN10 (3×3 mm) thermal performance (R_thJA = 52.7 °C/W).

Technical Context

The STEF12EPUR implements a precision current-sense architecture using an internal N-channel sense FET with fixed ratio to monitor load current and dynamically adjust MOSFET gate drive for accurate short-circuit (4.4 A typ) and overload (4.4 A) limiting. Its UVLO threshold (8.5 V typ) and 0.8 V hysteresis ensure stable turn-on under brown-out conditions.

Thermal protection uses a latch-type shutdown at 165 °C with fault indication via intermediate voltage (1.4 V typ) on the bi-directional En/Fault pin; reset is achieved by cycling VCC or pulling En/Fault below 0.58 V. The dv/dt pin supports external capacitor tuning of output voltage ramp time (0.5–2.6 ms range) without affecting core protection timing.

Key Specifications

Pinout & Package

STEF12EPUR is housed in a thermally enhanced DFN10L (3 × 3 mm) package with exposed VCC pad for optimal heat dissipation. Pin 11 is the exposed pad, electrically connected to VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCKE805M12A, STEF12EPUR offers superior design flexibility via programmable current limit and dv/dt control, while TPS25982L adds telemetry at the cost of larger footprint and higher BOM complexity - STEF12EPUR balances precision protection, compact size, and cost efficiency for storage-class 12 V rails.

Availability

STEF12EPUR is available at Aetrix Electronics and suitable for hard disk drives, solid-state drives, and set-top boxes requiring stable component supply, UL-certified protection, and DFN10 thermal performance.

Supply support for STEF12EPUR 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, specializing in power management, analog, and microcontroller solutions for industrial, automotive, and consumer markets.

STEF12EPUR belongs to ST's electronic fuse product line, engineered specifically for high-reliability 12 V power rail protection in storage subsystems - emphasizing fast fault response, thermal resilience, and seamless integration into space-constrained HDD/SSD designs.

FAQ

What is the recommended layout for the dv/dt pin to achieve a 2 ms output ramp time?

Per DS7315 Equation (2), a 2 ms ramp time requires C_dv/dt ≈ 78 nF. Place a 78 nF ±10% ceramic capacitor between Pin 2 (dv/dt) and GND, with minimal trace length and direct connection to ground plane. Avoid routing near noisy signals or switching nodes to prevent coupling into the slew-rate control loop.

How does the En/Fault pin behave during thermal shutdown, and what voltage level indicates this state?

During thermal shutdown, the En/Fault pin transitions to an intermediate voltage of 0.82–1.95 V (typ 1.4 V), distinct from its high (≥1.96 V) and low (≤0.58 V) states. This level is actively driven by internal circuitry and can directly interface with comparator inputs or GPIOs to trigger system-level thermal alerts without external components.

Can STEF12EPUR be used on a 5 V rail, and if not, what is the alternative?

No - STEF12EPUR is optimized for 12 V rails with UVLO (7.7–9.3 V) and clamp (13.8–16.2 V) thresholds centered around that range. For 5 V applications, ST offers the pin-compatible STEF05, which features 4.5–5.5 V UVLO and 6.2 V clamp, sharing identical DFN10 packaging and functional architecture.

What is the maximum allowable R_Limit value to maintain 3.3 A short-circuit current limit?

Using the formula R_Limit = 95 / I_Short, a 3.3 A short-circuit limit requires R_Limit ≈ 28.8 Ω. Per Table 5, R_Limit = 22 Ω yields 3.3–5.5 A; therefore, 28.8 Ω is within valid operating range but approaches upper bound - verify actual current with thermal derating at 125 °C junction temperature.