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

STMicroelectronics L6986FTR

Name: L6986FTR
Brand: STMicroelectronics
SKU: L6986FTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L6986FTR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 16-PowerTSSOP (0.173", 4.40mm Width)

Datasheet:: L6986FTR.pdf

Description:: IC REG BUCK ADJ 2A 16HTSSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L6986FTR from STMicroelectronics is a 38 V, 1.5 A synchronous step-down switching regulator with peak current mode control, 30 µA quiescent current in low-consumption mode (LCM), adjustable switching frequency (250 kHz–2 MHz), and embedded output voltage supervisor with open-drain RST. It supports 100% duty cycle operation via integrated P-channel high-side MOSFET and delivers regulated output from 0.85 V to VIN for industrial power rails.

For engineers reviewing the L6986FTR datasheet, L6986FTR pinout, L6986FTR application, or L6986FTR equivalent, key selection criteria include light-load efficiency (30 µA IQ), dual operating modes (LCM/LNM), adjustable soft-start, synchronization capability, overvoltage/thermal protection, and HTSSOP16 package thermal performance (R_thJA = 40 °C/W).

Technical Context

The L6986FTR implements peak current mode control with pulse-by-pulse high-side/low-side current sensing for constant-current protection and foldback under heavy short-circuit. Its switchover feature allows internal regulator supply to switch between VIN and external VBIAS (3–5.5 V), reducing effective input quiescent current.

Two configurable operating modes are selected via MLF pinstrapping: Low Noise Mode (LNM) enforces fixed-frequency PWM with minimized output ripple across load range; Low Consumption Mode (LCM) enables frequency reduction at light load to maximize efficiency while maintaining controlled ripple. Synchronization (master/slave) and output voltage sequencing via RST delay capacitor are fully supported.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4 V to 38 V - supports direct connection to 12 V and 24 V industrial buses without pre-regulation.
Output Current	1.5 A DC - sufficient for powering microcontrollers, FPGAs, and sensor signal chains in PLCs and distributed nodes.
Quiescent Current (LCM)	30 µA at light load (V_OUT = 3.3 V) - enables battery-backed or energy-harvesting systems to maintain long standby life.
Switching Frequency	Adjustable 250 kHz to 2 MHz via FSW pinstrapping - allows EMI optimization and compact magnetics selection.
Output Voltage Range	0.85 V to V_IN - supports core logic (0.85–1.2 V), I/O (1.8–3.3 V), and analog (5 V) rails from single converter.
R_DS(on) HS / LS	180 mΩ / 150 mΩ - reduces conduction losses and improves full-load efficiency in compact layouts.
Thermal Resistance	R_thJA = 40 °C/W (on ST demo board) - enables 1.5 A operation up to +85 °C ambient without forced airflow.

Pinout & Package

Package: HTSSOP16 (exposed pad), RoHS-compliant, thermal resistance R_thJA = 40 °C/W, R_thJC = 5 °C/W. Exposed pad must be connected to SGND and PGND for thermal and electrical integrity.

Pin/Terminal	Circuit Role	Design Meaning
1 RST	Open-collector reset output	Asserts low when V_OUT falls below programmable threshold; delay capacitor on Pin 8 sets release timing for power-up sequencing.
3 SS/INH	Soft-start/inhibit control	Internal 4 µA current source charges external capacitor for controlled ramp; pulled low disables regulator.
4 SYNCH/ISKP	Sync input / skip level select	In LNM: accepts external clock for master/slave sync; in LCM: selects current threshold for burst-mode entry.
5 FSW	Frequency selection	Resistor divider to VCC/GND sets f_SW from 250 kHz to 2 MHz before soft-start completes.
6 MLF	Mode and reset threshold select	Configures LNM vs LCM and selects RST trip point (80–96% of V_OUT) via resistor strapping.
7 COMP	Error amplifier output	Connects external compensation network (type II/III) to stabilize loop response across line/load transients.
9 FB	Feedback input	Inverting input of transconductance error amplifier; senses V_OUT via resistive divider referenced to 0.85 V internal bandgap.
10 SGND	Signal ground	Analog reference for error amp, comparators, and bias circuitry; separate from power ground to minimize noise coupling.
11 & 12 PGND	Power ground	High-current return path for HS/LS switches and inductor; must be low-inductance plane tied to exposed pad.
13 & 14 LX	Switching node	Drives external inductor; requires low-ESR ceramic capacitor and tight layout to minimize ringing and EMI.
15 VIN	Main input supply	Accepts 4–38 V; internal UVLO (2.7 V rising) prevents erratic startup during brownout.
16 VBIAS	Switchover auxiliary supply	When connected to regulated V_OUT, reduces effective IQ at VIN by powering part of analog circuitry from output rail.

Key Features

Feature	Design Value
100% duty cycle operation	Enabled by integrated P-channel high-side MOSFET - maintains regulation down to V_OUT ≈ V_IN − 0.3 V, critical for low-dropout industrial rails.
Embedded voltage supervisor with RST	Programmable reset threshold (80–96% of V_OUT) and adjustable delay - provides reliable µC/FPGA reset and multi-rail sequencing without external ICs.
Dual low-power operating modes	LCM achieves 30 µA IQ at light load; LNM maintains fixed f_SW and <10 mV_PP ripple - selectable per application noise/efficiency trade-off.
Synchronous rectification	Integrated N-channel low-side MOSFET replaces external diode - eliminates reverse recovery loss and improves efficiency >90% at medium/heavy loads.
Pulse-by-pulse overcurrent protection	Monitors both HS and LS current on every cycle - provides fast (<100 ns) shutdown and foldback during short-circuit, protecting external components.

Applications

Industrial PLC Power Supply

Decentralized Sensor Node

Use Scenario: Powering CPU, I/O modules, and communication interfaces in modular programmable logic controllers operating from 24 V bus.

IC Role / Device Role / Timing Role: Primary buck regulator delivering 3.3 V/1.2 V rails with sequencing and reset supervision for deterministic boot.

Use Value: 30 µA quiescent current extends backup battery life during maintenance mode; 38 V max input withstands 24 V bus transients per ISO 7637-2.

Use Scenario: Compact power stage for wireless sensor nodes deployed in factory automation, powered from 12 V field bus.

IC Role / Device Role / Timing Role: Single-chip solution providing regulated 1.8 V for MCU and 5 V for analog front-end with low-noise LNM mode.

Use Value: Adjustable f_SW allows EMI filtering at 1.2 MHz to avoid ISM bands; HTSSOP16 footprint minimizes PCB area in space-constrained enclosures.

Low-Noise Analog Signal Chain

Programmable Logic Controller I/O Module

Use Scenario: Powering precision ADCs, DACs, and op-amps in test equipment requiring ultra-low output ripple.

IC Role / Device Role / Timing Role: LNM-configured buck supplying 5 V with constant 2 MHz switching and synchronized clocks to suppress beat frequencies.

Use Value: <10 mV_PP ripple at full load ensures <1 LSB error in 16-bit ADCs; RST output coordinates analog power-up with digital controller.

Use Scenario: Isolated I/O module with digital inputs, outputs, and RS-485 transceivers drawing variable current from 24 V bus.

IC Role / Device Role / Timing Role: Main 5 V/1.5 A supply with adjustable soft-start to limit inrush into bulk capacitance and prevent bus sag.

Use Value: Programmable soft-start time (via CSS) controls dI/dt during power-up; thermal shutdown protects against sustained overload in sealed enclosures.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM5164QPWPRQ1	4.5–65 V input, 1 A output, 14 µA IQ, requires external HS FET; no integrated LDO or RST supervisor.	Better suited for automotive (AEC-Q100) and higher-input-voltage systems; lacks built-in sequencing or reset logic.	Select when input exceeds 38 V or AEC-Q100 qualification is mandatory; add external supervisor if RST required.
TPS54202DRCT	4.5–28 V input, 2 A output, 26 µA IQ, integrated FETs, but no RST output or VBIAS switchover.	Higher current and lower IQ than L6986FTR, but limited to 28 V input and lacks voltage sequencing capability.	Prefer for cost-sensitive 12 V systems needing >1.5 A; omit if supervisor functionality is handled elsewhere in BOM.

Compared with LM5164QPWPRQ1 and TPS54202DRCT, the L6986FTR uniquely integrates RST supervision with programmable delay, VBIAS switchover for ultra-low system IQ, and 38 V input rating - making it optimal for industrial 24 V bus applications requiring self-contained power management.

Availability

L6986FTR is available at Aetrix Electronics and suitable for industrial PLCs, decentralized sensor nodes, low-noise analog signal chains, and programmable logic controller I/O modules requiring stable component supply across extended temperature and long product lifecycles.

Supply support for L6986FTR 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 embedded markets.

The L6986FTR belongs to ST's high-voltage synchronous buck regulator family, designed specifically for robust, low-quiescent-current power conversion in harsh industrial environments with wide input voltage ranges and integrated system-level supervision.

FAQ

What is the purpose of the VBIAS pin on the L6986FTR?

The VBIAS pin enables switchover operation: when connected to a regulated output voltage (3–5.5 V), it supplies part of the internal analog circuitry, reducing effective quiescent current drawn from VIN. This is especially valuable in battery-powered or energy-sensitive applications where minimizing total system IQ is critical. If unused, VBIAS must be tied to GND.

How does the RST output support power sequencing?

The RST pin is an open-collector output that asserts low when V_OUT falls below a programmable threshold (set by MLF strapping). An external capacitor on the DELAY pin determines the time delay before RST releases after V_OUT rises above threshold. This enables precise power-up sequencing across multiple rails - for example, holding a microcontroller in reset until its core and I/O supplies are stable.

Can the L6986FTR synchronize to an external clock?

Yes - in Low Noise Mode (LNM), the SYNCH/ISKP pin accepts an external clock signal (266.5 kHz to 2 MHz) to synchronize switching frequency across multiple converters. This reduces beat frequencies and EMI peaks in multi-rail systems. The device supports up to six slave units per master clock, and synchronization remains active during all load conditions in LNM.

What thermal derating applies to the L6986FTR in HTSSOP16 package?

With R_thJA = 40 °C/W on ST's reference board, the L6986FTR delivers full 1.5 A output up to +85 °C ambient without forced airflow. Above this, output current must be reduced linearly: at +105 °C ambient, maximum continuous output drops to ~1.1 A. The exposed pad must be soldered to a minimum 100 mm² copper pour tied to both SGND and PGND to achieve specified thermal performance.

L6986FTR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 16-PowerTSSOP (0.173", 4.40mm Width)

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):: 4V

Voltage - Input (Max):: 38V

Voltage - Output (Min/Fixed):: 0.85V

Voltage - Output (Max):: 38V

Current - Output:: 2A

Frequency - Switching:: 250kHz ~ 2MHz

Synchronous Rectifier:: Yes

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-HTSSOP

L6986FTR FAQ

1.How can I place an order for L6986FTR through Aetrix?

Please submit a Request for Quotation (RFQ) for L6986FTR 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 L6986FTR reliable?

The price and inventory of L6986FTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L6986FTR is usually 5 days.

3.What payment methods are accepted for L6986FTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L6986FTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L6986FTR?

L6986FTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L6986FTR 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 L6986FTR?

For technical support, including L6986FTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L6986FTR requirements.

6.How does Aetrix verify that L6986FTR is sourced from the original manufacturer or authorized distributors?

All L6986FTR 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 L6986FTR meets industry standards.

7.What is the process for return or replacement of L6986FTR?

All L6986FTR units undergo pre-shipment inspection (PSI). If there is an issue with L6986FTR, 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 L6986FTR part is unused and in its original packaging.

Return procedure for L6986FTR:

1.Submit a request within 90 days.

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

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