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

STMicroelectronics L7986A

Name: L7986A
Brand: STMicroelectronics
SKU: L7986A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L7986A

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 8-SOIC (0.154", 3.90mm Width) Exposed Pad

Datasheet:: L7986A.pdf

Description:: IC REG BUCK ADJ 3A 8HSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L7986A from STMicroelectronics is a 3 A synchronous step-down switching regulator with integrated P-channel MOSFET, designed for high-efficiency DC-DC conversion in space-constrained 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 - used in FPGA core supplies and LCD TV main rails.

For engineers reviewing the L7986A datasheet, L7986A pinout, L7986A application, or L7986A equivalent, key selection criteria include input voltage range (4.5–38 V), output current capability (3 A continuous), thermal resistance (40 °C/W in HSOP8), and synchronization capability via SYNCH pin for multi-phase designs.

Technical Context

The L7986A implements voltage-mode PWM control with a fixed-frequency sawtooth oscillator whose slope is dynamically adjusted via voltage feed-forward (input-dependent ramp scaling) and frequency feed-forward (FSW-resistor–dependent ramp scaling) to maintain constant loop gain across input and frequency variations. The error amplifier drives COMP with ±30 mA sink/source capability and 100 dB open-loop gain.

It integrates UVLO (4.5 V turn-on, 0.4 V hysteresis), peak-current limiting (3.7–4.7 A), thermal shutdown (150 °C, 30 °C hysteresis), and a high-side P-MOSFET driver. Synchronization is bidirectional: SYNCH pin accepts external clocks or outputs phase-shifted signals for master-slave interleaving with 180° offset.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4.5 V to 38 V - supports wide-input industrial and automotive battery-derived rails without pre-regulation.
Output Current	3 A continuous - sustained under thermal limits (HSOP8: R_thJA = 40 °C/W; VFDFPN: 60 °C/W).
Output Voltage Range	0.6 V to V_IN - enables direct core supply for low-voltage FPGAs and processors using external resistor divider.
Switching Frequency	250 kHz (default) to 1 MHz - adjustable via FSW-to-GND resistor; higher frequencies reduce inductor size but increase switching loss.
Feedback Reference	0.6 V ±1.2% (0.582–0.618 V) - sets output accuracy and enables precise regulation of sub-1 V loads.
Quiescent Current	2.4 mA (active), 20–30 µA (standby) - enables low-power hold modes in always-on systems.
Thermal Shutdown	150 °C with 30 °C hysteresis - prevents latch-up during overload while allowing recovery after cooling.

Pinout & Package

Available in VFDFPN 3 × 3 mm (10-pin, exposed pad) and HSOP8 (exposed pad) packages. Both offer low thermal resistance for high-power density layouts.

Pin/Terminal	Circuit Role	Design Meaning
OUT	Power output node	Switch-node connection to LC filter; carries pulsed high-current waveform requiring low-inductance layout.
VCC	Unregulated input supply	Bias rail for internal circuitry; must be decoupled near pin with ≥10 µF ceramic capacitor.
GND	Power and signal reference	Common return for switch, feedback, and control circuits; tied to exposed pad for thermal conduction.
FB	Feedback input	Senses output voltage via resistor divider; 0.6 V reference sets regulation point; high-impedance input minimizes divider current.
COMP	Error amplifier output	Provides compensation node for Type II/III networks; ±30 mA drive supports stable loop design with ceramic or electrolytic output caps.
EN	Enable control	Active-high logic input (1.2 V threshold); allows system-level sequencing and standby mode control.
FSW	Frequency set/sync input	Resistor-to-GND sets frequency up to 1 MHz; floating defaults to 250 kHz; accepts external sync clock for phase alignment.
SYNCH	Sync I/O	Outputs 180° phase-shifted clock when floating; accepts external clock for master-slave interleaving; reduces input ripple RMS current.

Key Features

Feature	Design Value
Voltage feed-forward	Maintains constant PWM gain across 4.5–38 V input range by scaling sawtooth slope with V_IN, improving line transient response.
Frequency feed-forward	Adjusts sawtooth amplitude when FSW resistor changes frequency, preserving loop stability without re-compensation.
Zero-load operation	Regulates output at no load with <30 µA standby current - suitable for always-on auxiliary rails in networking equipment.
100% duty cycle capability	Supports dropout operation down to V_OUT = V_IN − 0.3 V, enabling high-efficiency LDO-like behavior at light loads.
Interleaved sync architecture	SYNCH pin enables two-phase interleaving with 180° phase shift, halving input capacitor RMS current and reducing EMI.

Applications

FPGA Core Supply

LCD TV Main Rail

Use Scenario: Powering Xilinx Artix-7 or Intel Cyclone V FPGA core logic at 1.0 V/2.5 A with tight voltage tolerance and fast load transient response.

IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated core voltage; uses FB/COMP loop for ±1% accuracy and 100 kHz–1 MHz switching for compact magnetics.

Use Value: Integrated 3.7 A current limit and thermal shutdown ensure safe operation during FPGA configuration surges; soft-start prevents inrush into large core capacitance.

Use Scenario: Generating 12 V/2 A backlight and 3.3 V/1.5 A logic rail in 32-inch LCD TV power board with shared heatsink.

IC Role / Device Role / Timing Role: Dual-output buck controller (with external FET for 12 V) or standalone 3.3 V rail; leverages 38 V max input to handle 24 V nominal supply with surge margin.

Use Value: VFDFPN package's 60 °C/W R_thJA enables convection-cooled operation; voltage feed-forward ensures stable regulation during AC line dips.

Industrial PLC I/O Module

DSL Modem DC-DC Stage

Use Scenario: Providing isolated 5 V/1.2 A and 3.3 V/0.8 A rails in DIN-rail mounted PLC module operating from 24 V DC field bus.

IC Role / Device Role / Timing Role: Non-isolated buck converter feeding downstream isolators and ADCs; uses EN pin for firmware-controlled power sequencing.

Use Value: Wide 4.5–38 V input accommodates brownout and reverse-polarity protection circuits; 20 µA standby current extends backup battery life.

Use Scenario: Converting 48 V phantom power to 3.3 V/0.5 A for ADSL2+ PHY and microcontroller in telecom CPE device.

IC Role / Device Role / Timing Role: High-input-voltage buck stage preceding LDOs; operates at 500 kHz to minimize EMI in sensitive analog front-end.

Use Value: Programmable frequency avoids noise coupling into DSL band; SYNC pin enables synchronization with Ethernet PHY clock to suppress beat frequencies.

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM5164QDRCRQ1	40 V max input, 0.6 A output, requires external MOSFETs; 100 kHz–2.2 MHz frequency range.	Lower current, higher frequency flexibility, AEC-Q100 qualified - suited for automotive body electronics.	Select when automotive qualification or >1 MHz operation is required; not drop-in due to external FET need and lower current rating.
MP2451DT-LF-Z	36 V max input, 0.6 A output, fixed 2 MHz frequency, no sync or feed-forward features.	Higher frequency enables smaller passives but lacks voltage/frequency feed-forward - limited line/load transient performance.	Choose for cost-sensitive, low-current consumer apps where compact size outweighs regulation precision and transient robustness.

Compared with LM5164QDRCRQ1 and MP2451DT-LF-Z, the L7986A uniquely combines 3 A integrated power delivery, 4.5–38 V input, voltage/frequency feed-forward, and synchronization - making it optimal for industrial and high-current consumer DC-DC where thermal management and transient immunity are critical.

Availability

L7986A is available at Aetrix Electronics and suitable for FPGA power supplies, LCD TV main rails, industrial PLC modules, and DSL modem DC-DC stages requiring stable component supply across extended temperature and long product lifecycles.

Supply support for L7986A 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 L7986A belongs to ST's high-voltage buck regulator product line, engineered for robust, high-current DC-DC conversion in harsh environments with minimal external components and superior thermal performance.

FAQ

What is the maximum output current the L7986A can sustain continuously?

The L7986A delivers up to 3 A DC output current under typical thermal conditions. This is validated with HSOP8 package on a standard demo board (R_thJA = 40 °C/W) at T_A ≤ 60 °C and V_IN = 12 V. At higher ambient temperatures or with VFDFPN (R_thJA = 60 °C/W), derating applies per Figure 22–24 in the datasheet.

Does the L7986A support output voltages below 0.6 V?

No - the internal reference is fixed at 0.6 V, and the FB pin is designed for resistive divider feedback. Output voltage cannot be set below 0.6 V. For sub-0.6 V regulation, an external reference or dedicated low-V_REF controller is required.

How does the SYNCH pin function when two L7986A devices are interconnected?

When SYNCH pins of two L7986A devices are wired together, the unit with higher switching frequency automatically acts as master, forcing the other into slave mode with 180° phase shift. This interleaving reduces input capacitor RMS current and improves thermal distribution across both regulators.

Can the L7986A operate with no output load?

Yes - the L7986A supports zero-load operation with quiescent current as low as 20–30 µA in standby mode. It maintains regulation and responds to load transients even at no load, verified across the full input range (4.5–38 V) and temperature range (−40 to +125 °C).

L7986A Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width) Exposed Pad

Packaging:: Tube

Product Status:: Active

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:: 8-HSOP

L7986A FAQ

1.How can I place an order for L7986A through Aetrix?

Please submit a Request for Quotation (RFQ) for L7986A 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 L7986A reliable?

The price and inventory of L7986A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L7986A is usually 5 days.

3.What payment methods are accepted for L7986A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L7986A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L7986A?

L7986A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L7986A 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 L7986A?

For technical support, including L7986A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L7986A requirements.

6.How does Aetrix verify that L7986A is sourced from the original manufacturer or authorized distributors?

All L7986A 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 L7986A meets industry standards.

7.What is the process for return or replacement of L7986A?

All L7986A units undergo pre-shipment inspection (PSI). If there is an issue with L7986A, 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 L7986A part is unused and in its original packaging.

Return procedure for L7986A:

1.Submit a request within 90 days.

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

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