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

STMicroelectronics L7986TR

Name: L7986TR
Brand: STMicroelectronics
SKU: L7986TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L7986TR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 10-VFDFN Exposed Pad

Datasheet:: L7986TR.pdf

Description:: IC REG BUCK ADJUSTABLE 3A

Quantity:: RFQ Add To RFQ list

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Inventory:11,077

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Product details

Overview

L7986TR 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 rails. 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/PLD core supplies and LCD TV main power stages.

For engineers reviewing the L7986TR datasheet, L7986TR pinout, L7986TR application, or L7986TR equivalent, this page provides verified technical context, validated pin functions, confirmed thermal performance (R_thJA = 60 °C/W in VFDFPN), and real-world application constraints including voltage feed-forward behavior and synchronization phase-shift requirements.

Technical Context

The L7986TR 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 PWM gain across input and frequency variations. The error amplifier compares FB voltage against a trimmed 0.6 V reference and drives COMP for external Type II or Type III compensation.

It integrates a high-side P-MOSFET with 200–400 mΩ R_DS(on), peak current limiting at 3.7–4.7 A, thermal shutdown at 150 °C with 30 °C hysteresis, and UVLO with 4.5 V turn-on threshold and 0.1–0.4 V hysteresis. Synchronization is achieved via the SYNCH pin, supporting master/slave phase-shifted operation or external clock locking with <110 ns pulse width tolerance.

Key Specifications

Parameter	Value and Actual Design Meaning
Output current	3 A continuous DC load current under thermal limits (R_thJA = 60 °C/W in VFDFPN)
Input voltage range	4.5 V to 38 V - supports wide-input industrial rails and automotive battery transients
Output voltage range	0.6 V to V_IN - enables core supply for FPGAs (e.g., 1.2 V, 1.8 V) and analog subsystems
Switching frequency	250 kHz (default) to 1 MHz - adjustable via resistor on FSW pin for EMI/noise optimization
Feedback reference	0.6 V ±1.2% - sets output accuracy; requires external resistor divider for V_OUT > 0.6 V
Quiescent current	2.4 mA active, 20–30 µA standby - enables low-power hold modes in always-on systems
Thermal shutdown	150 °C junction with 30 °C hysteresis - prevents thermal runaway during overload or poor heatsinking

Pinout & Package

Available in VFDFPN 3 × 3 mm (10-lead, exposed pad) and HSOP8 (exposed pad) packages. The VFDFPN variant achieves R_thJA = 60 °C/W; HSOP8 achieves 40 °C/W on demo board layout.

Pin/Terminal	Circuit Role	Design Meaning
OUT	Power switch output node	Connects to LC filter inductor; carries full switched current and ripple
VCC	Unregulated input supply	Bias source for internal circuitry; must be decoupled near pin with ≥10 µF ceramic
GND	Power and signal ground reference	Shared return for switch, error amp, and UVLO; requires low-inductance connection to exposed pad
FB	Feedback input	Senses output voltage via resistor divider; regulates to 0.6 V reference
COMP	Error amplifier output	Drives external compensation network (Type II/III); sink/source capability up to 30 mA
EN	Enable control input	Active-high logic (ON > 1.2 V, OFF < 0.3 V); supports sequencing and power-down
FSW	Frequency set/synchronization input	Resistor-to-ground sets frequency; floating = 250 kHz; accepts external sync clock
SYNCH	Sync output/input	Generates 180° phase-shifted clock; enables multi-phase interleaving when tied between devices

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
Frequency feed-forward	Preserves PWM gain stability when FSW resistor adjusts frequency up to 1 MHz
Zero-load operation	Regulates output with no minimum load required - eliminates need for dummy resistors
100% duty cycle capability	Supports low-dropout operation near V_OUT ≈ V_IN, e.g., 5 V → 4.8 V post-regulation
Internal soft-start	64-step staircase ramp (9.5 mV/step) yields 7.4–9.1 ms startup time depending on F_SW

Applications

FPGA Core Supply

Automotive Infotainment Power

Use Scenario: Providing clean, tightly regulated 1.2 V or 1.8 V to Xilinx/Intel FPGA core logic with dynamic current demand up to 2.5 A.

IC Role / Device Role / Timing Role: Primary buck converter delivering core voltage; handles fast load transients (0.4 A → 2 A in <10 µs per Figure 30).

Use Value: Voltage feed-forward ensures consistent transient response across battery voltage swings (9–16 V), while soft-start prevents inrush into large FPGA bulk capacitance.

Use Scenario: Generating 5 V and 3.3 V rails for head unit MCU, audio codec, and display interface in 12 V automotive systems.

IC Role / Device Role / Timing Role: Main DC-DC regulator handling cold-crank (4.5 V) and load-dump (38 V) conditions per ISO 7637-2.

Use Value: Wide 4.5–38 V input range and thermal shutdown (150 °C) ensure reliability in under-hood temperature environments without derating.

LCD TV Main Power

Industrial PLC I/O Module

Use Scenario: Delivering 12 V at 3 A to LCD backlight drivers and TCON logic in 24 V-powered displays.

IC Role / Device Role / Timing Role: High-current buck stage preceding secondary point-of-load converters; synchronized via SYNCH pin to reduce input capacitor RMS current.

Use Value: Phase-shifted dual-device synchronization cuts input ripple current by ~30%, enabling smaller 105 °C input capacitors.

Use Scenario: Generating isolated 5 V and 3.3 V supplies for digital I/O and communication interfaces (RS-485, CAN) in DIN-rail mounted controllers.

IC Role / Device Role / Timing Role: Non-isolated primary regulator accepting 24 V DC field bus input; operates continuously at 60 °C ambient.

Use Value: VFDFPN package's 60 °C/W R_thJA allows full 3 A output at 60 °C ambient without forced air, reducing system cooling cost.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM5164QDDARQ1	42 V max input, 0.5 A output, integrated N-MOSFET; requires external bootstrap capacitor	Lower current rating; suited for auxiliary rails, not main FPGA/core supplies	Select only if output current ≤ 0.5 A and bootstrap layout complexity is acceptable
MP2451DT-LF-Z	36 V max input, 0.6 A output, fixed 2.5 V or adjustable output; no SYNC or soft-start pin	Lacks synchronization, soft-start, and current capability - limited to low-power peripherals	Use only for non-critical 0.6 A loads where timing control and sequencing are unnecessary

Compared with LM5164QDDARQ1 and MP2451DT-LF-Z, the L7986TR uniquely delivers 3 A output with integrated P-MOSFET, programmable frequency, synchronization, and zero-load operation - making it suitable for demanding core power applications where current, thermal, and timing control are critical.

Availability

L7986TR is available at Aetrix Electronics and suitable for FPGA power delivery, automotive infotainment systems, and industrial PLC I/O modules requiring stable component supply across extended temperature and input voltage ranges.

Supply support for L7986TR 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, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The L7986TR belongs to ST's high-voltage buck regulator product line, engineered for robust DC-DC conversion in harsh environments - emphasizing wide input range, thermal resilience, and flexible synchronization for multi-rail systems.

FAQ

What is the maximum recommended output current for L7986TR in VFDFPN package at 60 °C ambient?

The L7986TR delivers up to 3 A continuous output current in VFDFPN package at 60 °C ambient when mounted on a standard 4-layer PCB with 2 oz copper and thermal vias to internal ground planes. This assumes 4.5–12 V input, 3.3 V output, and proper input/output capacitor selection per Section 6 of the datasheet. Junction temperature remains below 125 °C under these conditions.

Can L7986TR operate with input voltage below 4.5 V?

No. The L7986TR has a guaranteed turn-on threshold of 4.5 V (V_CCON) with 0.1–0.4 V hysteresis. Operation below 4.5 V is outside specification and may result in erratic enable behavior, failure to start, or undefined regulation. For sub-4.5 V inputs, consider ST's L5973D (3.5 V min) or alternative low-V_IN buck regulators.

How does the SYNCH pin behave when left floating?

When the SYNCH pin is left floating, it outputs a square wave synchronized to the internal oscillator with a 180° phase shift relative to the power switch turn-on edge. This inherent phase inversion enables natural interleaving when two L7986TR devices have their SYNCH pins tied together - one acts as master, the other as slave, achieving half-cycle offset without external timing components.

Is external compensation mandatory for stable operation?

Yes. The COMP pin is the error amplifier output and requires an external Type II or Type III compensation network connected between COMP, FB, and GND. Stability depends on matching the network to the selected output capacitor ESR and LC filter values. Table 4 and Figures 10–15 in the datasheet provide design equations and Bode plots for both ceramic and electrolytic output capacitor configurations.

L7986TR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 10-VFDFN Exposed Pad

Packaging:: Tape & Reel (TR)

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:: -

L7986TR FAQ

1.How can I place an order for L7986TR through Aetrix?

Please submit a Request for Quotation (RFQ) for L7986TR 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 L7986TR reliable?

The price and inventory of L7986TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L7986TR is usually 5 days.

3.What payment methods are accepted for L7986TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L7986TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L7986TR?

L7986TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L7986TR 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 L7986TR?

For technical support, including L7986TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L7986TR requirements.

6.How does Aetrix verify that L7986TR is sourced from the original manufacturer or authorized distributors?

All L7986TR 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 L7986TR meets industry standards.

7.What is the process for return or replacement of L7986TR?

All L7986TR units undergo pre-shipment inspection (PSI). If there is an issue with L7986TR, 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 L7986TR part is unused and in its original packaging.

Return procedure for L7986TR:

1.Submit a request within 90 days.

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

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