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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Current Regulation/Management

STMicroelectronics STEF12SAGR

Name: STEF12SAGR
Brand: STMicroelectronics
SKU: STEF12SAGR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STEF12SAGR

Manufacturer:: STMicroelectronics

Category:: Current Regulation/Management

Package:: SOT-23-8 Thin, TSOT-23-8

Datasheet:: STEF12SAGR.pdf

Description:: DISCRETE

Quantity:: RFQ Add To RFQ list

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Product details

Overview

STEF12SAGR from STMicroelectronics is a latch-mode 12 V electronic fuse with integrated 40 mΩ N-channel power MOSFET, 15 V typical overvoltage clamp, adjustable current limit (1.5–8 A via RLim), thermal shutdown at 165 °C, and input undervoltage lockout at 8.5 V. It protects hard disk drives, SSDs, and hot-swap boards by limiting fault current and regulating output during overvoltage events.

For engineers reviewing the STEF12SAGR datasheet, STEF12SAGR pinout, STEF12SAGR application, or STEF12SAGR equivalent, key selection criteria include programmable current limit accuracy, dV/dt-controlled soft-start for inrush control, EN/Fault pin tri-state signaling for thermal fault detection, and DFN10 package support for reverse-current blocking via VG gate driver.

Technical Context

The STEF12SAGR implements a precision current-sense architecture using an internal N-channel sense FET with fixed ratio to monitor load current and enforce user-defined ILIM/ISHORT thresholds via external RLim resistor. Its clamping circuit actively regulates VOUT to ≤16.2 V when VIN exceeds 17 V, increasing power dissipation until thermal shutdown triggers at 165 °C.

It features dual-mode EN/Fault pin operation: floating or high enables soft-start (250 µs delay + 0.85 ms default ramp); low disables output; intermediate voltage (~1.3 V) signals thermal fault in latch mode. The DFN10 variant adds VG pin to drive external reverse-blocking MOSFET during input brownout.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CLAMP	15 V typical - limits output to safe level during input overvoltage (e.g., 17 V rail surge), preventing downstream damage.
R_DS(on)	40 mΩ typ. at 25 °C - yields ≤42 mV drop at 1 A, minimizing conduction loss in 12 V power path.
I_LIM Range	1.5–8 A - set by RLim (15.4–300 Ω); e.g., 22 Ω gives 5.5 A overload limit for HDD spindle motor startup.
T_SHDN	165 °C - shuts off MOSFET to protect die; 20 °C hysteresis enables recovery only after cooling to ~145 °C.
V_UVLO	8.5 V typ. with 0.8 V hysteresis - prevents erratic operation during brownout; ensures clean turn-on above 9.3 V.
dV/dt Ramp	0.85 ms (10%→90% VOUT) - controls inrush into large capacitive loads (e.g., SSD power rails) without tripping current limit.
V_G Drive	5 V above VOUT - directly biases external N-MOSFET gate for reverse-current blocking during input loss (DFN10 only).

Pinout & Package

STEF12SAGR is available in DFN10 (3×3 mm, 0.5 mm pitch) package with exposed thermal pad. Pin functions are validated per DS13002 Rev 6 (p.3).

Pin / Terminal	Circuit Role	Design Meaning
ILim	Current limit programming node	Connects to RLim resistor between this pin and Source; sets precise ILIM/ISHORT thresholds (e.g., 22 Ω → 5.5 A/2.8 A).
En/Fault	Tri-state enable/fault reporting	Float = enable; pull-low = disable; intermediate ~1.3 V = thermal fault signal; supports daisy-chaining for coordinated shutdown.
dV/dt	Soft-start timing control	Internal 0.85 ms ramp; add external capacitor to extend ramp time (e.g., 100 pF → 3 ms) for large COUT loads.
GND	Power and signal reference	Low-impedance return path for sense circuitry, gate driver, and thermal monitoring; must be solidly connected to PCB ground plane.
VCC	Main power input	Accepts 10–13.8 V nominal; absolute max 25 V; powers internal charge pump, gate driver, and protection logic.
Source/VOUT	Output power terminal	Drives load; connects to internal MOSFET source; voltage drop determined by RDS(on) × ILOAD.
VG	External MOSFET gate driver	Outputs 5 V above VOUT to turn on external reverse-blocking N-MOSFET during input brownout (DFN10 only).

Key Features

Feature	Design Value
Adjustable current limit	Programmable 1.5–8 A overload threshold via single RLim resistor, enabling precise matching to HDD/SSD peak current profiles.
Overvoltage clamp	15 V typical clamping with ±1.2 V tolerance ensures downstream 12 V ICs (e.g., SATA controllers) remain within ABS MAX ratings during rail surges.
Thermal protection with latch	165 °C shutdown with non-volatile latch behavior requires supply cycle or EN pin reset-prevents automatic retry during persistent overheating.
Controlled soft-start	Configurable dV/dt ramp (0.85–22 ms) eliminates inrush-induced voltage droop in multi-drive storage enclosures during hot-plug insertion.
Reverse current blocking (DFN10)	VG pin delivers regulated gate drive to external N-MOSFET, enabling controlled power-down sequencing (e.g., SSD write-cache flush) during input loss.

Applications

Hard Disk Drives

SSD Power Management

Use Scenario: Protecting 3.5" HDDs in enterprise NAS systems during hot-swap insertion and transient overcurrent events.

IC Role / Device Role / Timing Role: Series-connected eFuse providing real-time current limiting, UVLO hold-off, and 15 V clamping during 12 V rail instability.

Use Value: Prevents HDD controller damage from inrush spikes (>5 A) and sustains operation through 8.5–9.3 V brownouts without spurious resets.

Use Scenario: Securing M.2 and U.2 SSDs against overvoltage and reverse current during PCIe hot-plug and power-loss events.

IC Role / Device Role / Timing Role: Primary 12 V rail protector with dV/dt-controlled ramp and VG-driven reverse-blocking FET for cache-flush retention.

Use Value: Enables guaranteed 10–100 ms hold-up time via external COUT and reverse-FET control, meeting JEDEC JESD219 data integrity requirements.

Hot-Swap Board Protection

RAID Controller Power Rails

Use Scenario: Safeguarding backplane slots in modular server chassis where cards are inserted under live 12 V power.

IC Role / Device Role / Timing Role: Fast-response electronic fuse with 250 µs enable delay and 0.85 ms soft-start to avoid bus voltage collapse during card insertion.

Use Value: Limits peak inrush to <3 A while maintaining ≥11.9 V at load, ensuring stable enumeration of PCIe devices without link training failure.

Use Scenario: Isolating redundant 12 V supplies feeding RAID controller ASICs and cache DRAM in storage arrays.

IC Role / Device Role / Timing Role: Dual-rail eFuse (with STEF05S companion) enforcing coordinated shutdown across 12 V and 5 V domains during thermal faults.

Use Value: Tri-state EN/Fault pin allows daisy-chained fault propagation, guaranteeing simultaneous power removal to prevent data corruption during thermal events.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
STEF12SA	Autoretry mode instead of latch; EN/Fault goes low during thermal fault and auto-restarts after cooling to 145 °C.	Suitable for non-critical loads where continuous availability outweighs controlled shutdown (e.g., fan power rails).	Select STEF12SA only if system firmware can tolerate uncontrolled restarts; STEF12SAGR's latch prevents repeated thermal cycling in constrained airflow.
TCKE805M12A	Fixed 5.5 A current limit, no RLim adjustment; lacks dV/dt control and VG pin; rated for 12 V ±10 % only.	Targeted at cost-sensitive consumer HDD enclosures without reverse-blocking or programmable ramp needs.	Use TCKE805M12A only for simple overcurrent-only protection; STEF12SAGR provides superior design flexibility for enterprise storage with full parameter tuning.

Compared with STEF12SA, STEF12SAGR avoids uncontrolled retries during thermal stress, while versus TCKE805M12A it delivers field-programmable current limits, soft-start control, and reverse-current blocking-critical for data integrity in RAID and SSD systems.

Availability

STEF12SAGR is available at Aetrix Electronics and suitable for hard disk drives, SSD power management, hot-swap board protection, and RAID controller power rails requiring stable component supply across industrial temperature range and long lifecycle support.

Supply support for STEF12SAGR 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 automotive-grade ICs with ISO 9001 and IATF 16949 certified manufacturing.

The STEF series targets high-reliability data storage and infrastructure applications, delivering integrated eFuse functionality with programmable protection parameters to replace discrete fuse + controller solutions in 12 V power distribution networks.

FAQ

What is the function of the ILim pin, and how does it affect current limiting?

The ILim pin connects to an external resistor (RLim) between itself and the Source/VOUT pin to set precise overload and short-circuit current thresholds. For STEF12SAGR, a 22 Ω RLim resistor configures 5.5 A overload limit and 2.8 A short-circuit limit. Missing or shorted RLim disables current limiting and risks device destruction under fault conditions, as stated in DS13002 Section 3.

Does STEF12SAGR support reverse current blocking, and which package enables it?

Reverse current blocking is supported only on the DFN10 (3×3 mm) package via the VG pin, which sources 5 V above VOUT to drive an external N-channel MOSFET. The TSOT23-8L variant lacks VG and cannot implement active reverse-blocking; it relies on external Schottky diodes or series diodes per DS13002 Section 6.8 and Figure 4.

How does the EN/Fault pin behave during thermal shutdown?

In STEF12SAGR (latch version), the EN/Fault pin transitions to an intermediate voltage of 1.2–1.45 V during thermal shutdown to signal the fault condition. This state persists until reset by cycling VCC or pulling EN/Fault below 1.8 V and releasing. Unlike autoretry versions, it does not self-recover, ensuring deliberate system intervention before re-enabling power.

What are the mandatory external components for stable operation?

Mandatory components include: ≥1 µF CIN between VCC and GND (placed adjacent to pins), ≥1 µF COUT between Source/VOUT and GND, and RLim resistor tied between ILim and Source/VOUT. DS13002 Section 6.9 specifies Cdv/dt capacitor is optional but recommended for large COUT loads to extend soft-start ramp time beyond the default 0.85 ms.

STEF12SAGR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: SOT-23-8 Thin, TSOT-23-8

Packaging:: Bulk

Product Status:: Active

Function:: Electronic Fuse

Sensing Method:: High-Side

Accuracy:: -

Voltage - Input:: 10V ~ 13.8V

Current - Output:: 3.5A

Operating Temperature:: -40°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: TSOT-23-8L

STEF12SAGR FAQ

1.How can I place an order for STEF12SAGR through Aetrix?

Please submit a Request for Quotation (RFQ) for STEF12SAGR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for STEF12SAGR reliable?

The price and inventory of STEF12SAGR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STEF12SAGR is usually 5 days.

3.What payment methods are accepted for STEF12SAGR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STEF12SAGR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STEF12SAGR?

STEF12SAGR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STEF12SAGR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for STEF12SAGR?

For technical support, including STEF12SAGR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STEF12SAGR requirements.

6.How does Aetrix verify that STEF12SAGR is sourced from the original manufacturer or authorized distributors?

All STEF12SAGR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that STEF12SAGR meets industry standards.

7.What is the process for return or replacement of STEF12SAGR?

All STEF12SAGR units undergo pre-shipment inspection (PSI). If there is an issue with STEF12SAGR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The STEF12SAGR part is unused and in its original packaging.

Return procedure for STEF12SAGR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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