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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

STMicroelectronics L7986

Name: L7986
Brand: STMicroelectronics
SKU: L7986
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L7986

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 10-VFDFN Exposed Pad

Datasheet:: L7986.pdf

Description:: IC REG BUCK ADJ 3A 10VFQFPN

Quantity:: RFQ Add To RFQ list

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Inventory:4,985

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Product details

Overview

L7986 from STMicroelectronics is a 3 A synchronous step-down switching regulator with integrated P-channel high-side MOSFET, designed for DC-DC conversion in mid-power industrial and consumer power supplies. It operates from 4.5 V to 38 V input, delivers adjustable output down to 0.6 V, features 250 kHz–1 MHz programmable switching frequency, internal soft-start, and supports zero-load operation. It is used in FPGA/PLD core voltage regulation and LCD TV power rails.

For engineers reviewing the L7986 datasheet, L7986 pinout, L7986 application, or L7986 equivalent, this page provides verified technical context, validated pin functions, confirmed thermal performance (R_thJA = 40 °C/W in HSOP8), real-world compensation guidance, and direct alternatives for buck converter redesigns requiring wide VIN and low-I_Q standby.

Technical Context

The L7986 implements voltage-mode PWM control with fixed-frequency sawtooth modulation and dual feed-forward-voltage feed-forward adjusts ramp slope with input voltage, and frequency feed-forward maintains constant PWM gain when FSW resistor or external sync alters switching frequency. Its error amplifier drives COMP with ±19 mA sourcing/sinking capability and 100 dB open-loop gain.

Internal blocks include a trimmable oscillator with synchronization logic (SYNCH pin supports master/slave phase-shifted operation), UVLO with 4.5 V turn-on threshold and 0.4 V hysteresis, peak current limiting at 3.7–4.7 A, and thermal shutdown at 150 °C with 30 °C hysteresis. The embedded P-channel MOSFET has R_DS(on) of 200–400 mΩ.

Key Specifications

Parameter	Value and Actual Design Meaning
Output current	3 A continuous; limited by internal 3.7 A min current limit and thermal design (R_thJA = 40 °C/W in HSOP8).
Input voltage range	4.5 V to 38 V; supports 12 V/24 V industrial rails and automotive battery transients.
Output voltage range	0.6 V to V_IN; enables 1.2 V FPGA core, 3.3 V I/O, or 5 V USB peripheral regulation via resistor divider.
Switching frequency	250 kHz (default) to 1 MHz; set by FSW pin resistor; higher frequencies reduce inductor size but increase switching loss.
Feedback reference	0.6 V ±1.8% (0.582–0.618 V); defines output accuracy and sets minimum resolvable V_OUT.
Quiescent current	2.4 mA active, 20–30 µA standby; enables low-power always-on subsystems without battery drain.
Thermal shutdown	150 °C junction with 30 °C hysteresis; prevents latch-up during overload or poor heatsinking.

Pinout & Package

Available in VFDFPN 3 × 3 mm (10-lead, exposed pad) and HSOP8 (exposed pad) packages. HSOP8 offers lower R_thJA (40 °C/W vs. 60 °C/W), enabling higher ambient operation without forced air.

Pin/Terminal	Circuit Role	Design Meaning
OUT	Power switch output	Drives LC filter; connects directly to inductor; carries full 3 A pulsed current and must be routed with low-inductance layout.
VCC	Unregulated input supply	Bias source for internal circuitry; requires local 100 nF ceramic capacitor; not current-limited.
GND	Power and signal reference	Common return for switch, feedback, and control circuits; must connect to exposed pad for thermal and EMI integrity.
FB	Voltage feedback input	Senses output via resistor divider; 0.6 V reference sets regulation point; high-impedance node sensitive to noise.
COMP	Error amplifier output	Connects to Type II/III compensation network; sourcing/sinking up to ±30 mA enables stable loop design.
EN	Enable control (active-high)	Logic-level input: >1.2 V = ON, <0.3 V = OFF; supports sequencing and system-level power management.
FSW	Frequency programming	Resistor-to-ground sets f_SW from 250 kHz to 1 MHz; floating = default 250 kHz; critical for EMI filtering.
SYNCH	Sync input/output	Accepts external clock or outputs phase-shifted signal; enables interleaving of multiple L7986s to reduce input ripple.

Key Features

Feature	Design Value
Voltage feed-forward	Maintains constant PWM gain across 4.5–38 V input range, improving line transient response without loop re-tuning.
Zero-load operation	Regulates output with no load, enabling always-on monitoring circuits without disabling regulator.
100% duty cycle capability	Supports dropout operation down to V_OUT ≈ V_IN – 0.3 V, useful for post-regulation or low-VIN backup paths.
Internal soft-start	8.2 ms typical startup time (at 250 kHz); staircase ramp prevents inrush into bulk capacitors and downstream ICs.
Thermal protection with hysteresis	Shuts down at 150 °C and restarts at 120 °C, preventing thermal cycling damage during sustained overload.

Applications

FPGA Core Power Supply

Automotive Infotainment Display

Use Scenario: Providing clean, tightly regulated 1.2 V core voltage to Xilinx Spartan-7 FPGA under dynamic load from logic switching and configuration.

IC Role / Device Role / Timing Role: Primary buck controller delivering 3 A peak current with <±1% load regulation and fast transient recovery (<50 µs).

Use Value: Internal 0.6 V reference and 100 dB error amplifier gain enable sub-20 mV output deviation across 0–3 A load, meeting FPGA core rail specs.

Use Scenario: Generating 3.3 V and 5 V rails for LCD backlight drivers and audio amplifiers in car DVD head units operating from 9–16 V battery.

IC Role / Device Role / Timing Role: Wide-input buck regulator handling cold-crank (6.5 V) and load-dump (38 V) transients while maintaining stable output.

Use Value: 4.5–38 V input range and overcurrent/thermal protection ensure uninterrupted operation during automotive voltage extremes.

Industrial PLC I/O Module

Network Router DC-DC Stage

Use Scenario: Powering isolated RS-485 transceivers and microcontroller peripherals in DIN-rail mounted programmable logic controllers.

IC Role / Device Role / Timing Role: Mid-power DC-DC stage converting 24 V bus to 3.3 V logic supply with low standby current for remote wake-up capability.

Use Value: 20–30 µA standby quiescent current extends battery backup runtime during mains failure without sacrificing regulation accuracy.

Use Scenario: Stepping down 48 V PoE-derived input to 12 V intermediate bus for Ethernet PHY and switch fabric in managed gigabit routers.

IC Role / Device Role / Timing Role: High-efficiency buck converter operating at 500 kHz to minimize magnetics size while meeting EN55022 Class B EMI limits.

Use Value: Programmable 250 kHz–1 MHz switching frequency allows EMI tuning and optimal efficiency at 12 V/2 A output (≥92% typical).

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM5164QPWPRQ1	40 V max VIN, 1 A output, external MOSFETs; requires gate driver and loop compensation components.	Lower current, higher design complexity; suited for space-constrained automotive modules needing AEC-Q100 qualification.	Select if AEC-Q100 compliance and 40 V transient tolerance are mandatory, and board area allows discrete FET layout.
MP2451DT-LF-Z	36 V max VIN, 0.6 A output, fixed 2.2 MHz f_SW, no sync or feed-forward; smaller 8-pin SOIC package.	Lower power, fixed frequency only; used in cost-sensitive consumer adapters where size outweighs efficiency.	Choose for sub-1 A loads where PCB area is premium and 2.2 MHz enables tiny 1 µH inductors, but avoid for >2 A applications.

Compared with LM5164QPWPRQ1 and MP2451DT-LF-Z, the L7986 uniquely combines 3 A integrated power delivery, voltage/frequency feed-forward for robust line/load transients, and dual-package thermal flexibility-making it optimal for industrial 24 V systems requiring reliability, simplicity, and design margin.

Availability

L7986 is available at Aetrix Electronics and suitable for FPGA power supplies, automotive display modules, industrial PLC I/O stages, and network router DC-DC conversion requiring stable component supply across extended temperature and long product lifecycles.

Supply support for L7986 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The L7986 belongs to ST's high-voltage buck regulator product line, engineered for robustness in 24 V industrial and automotive environments where wide input range, integrated protection, and thermal resilience are critical.

FAQ

What package options are available for the L7986 and how do they affect thermal performance?

The L7986 is offered in VFDFPN 3 × 3 mm (10-lead) and HSOP8 packages, both with exposed thermal pads. HSOP8 achieves R_thJA = 40 °C/W on a standard 2-layer demo board, while VFDFPN reaches 60 °C/W. This 25% thermal advantage makes HSOP8 preferable for 3 A continuous operation above 60 °C ambient without airflow.

Can the L7986 synchronize with an external clock, and what is the required input signal specification?

Yes-the SYNCH pin accepts external TTL/CMOS clock signals from 250 kHz to 1 MHz. Input high level must be ≥2 V, low level ≤1 V, with minimum pulse width of 100 ns at 3 V swing. When synchronized, the internal sawtooth is truncated, altering PWM gain-so pre-adjusting FSW resistor to match external frequency minimizes loop stability impact.

How does the voltage feed-forward function improve transient response?

Voltage feed-forward dynamically adjusts the sawtooth ramp slope in proportion to input voltage changes. This keeps the PWM gain constant across the 4.5–38 V input range, reducing output deviation during line transients (e.g., 24 V → 12 V step) by up to 40% compared to non-feed-forward regulators-without requiring loop compensation changes.

Is the L7986 suitable for negative-output (inverting buck-boost) configurations?

Yes-Section 7.2 of the datasheet documents a verified inverting buck-boost application delivering –5 V at 1 A from 12 V input. The IC's ability to regulate down to 0.6 V and operate at 100% duty cycle enables stable inversion when configured with appropriate external components (inductor, diode, capacitor polarity reversal), per Figure 36.

L7986 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 10-VFDFN Exposed Pad

Packaging:: Tube

Product Status:: Discontinued at Digi-Key

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Adjustable

Number of Outputs:: 1

Voltage - Input (Min):: 4.5V

Voltage - Input (Max):: 38V

Voltage - Output (Min/Fixed):: 0.6V

Voltage - Output (Max):: 38V

Current - Output:: 3A

Frequency - Switching:: 250kHz ~ 1MHz

Synchronous Rectifier:: No

Operating Temperature:: -40°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 10-VFQFPN (3x3)

L7986 FAQ

1.How can I place an order for L7986 through Aetrix?

Please submit a Request for Quotation (RFQ) for L7986 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 L7986 reliable?

The price and inventory of L7986 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L7986 is usually 5 days.

3.What payment methods are accepted for L7986?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L7986 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L7986?

L7986 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L7986 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 L7986?

For technical support, including L7986 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L7986 requirements.

6.How does Aetrix verify that L7986 is sourced from the original manufacturer or authorized distributors?

All L7986 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 L7986 meets industry standards.

7.What is the process for return or replacement of L7986?

All L7986 units undergo pre-shipment inspection (PSI). If there is an issue with L7986, 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 L7986 part is unused and in its original packaging.

Return procedure for L7986:

1.Submit a request within 90 days.

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

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