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

STMicroelectronics L6986H3V3TR

Name: L6986H3V3TR
Brand: STMicroelectronics
SKU: L6986H3V3TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L6986H3V3TR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

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

Datasheet:: L6986H3V3TR.pdf

Description:: IC REG BUCK 3.3V 2A 16HTSSOP

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Product details

Overview

L6986H3V3TR from STMicroelectronics is a 2 A synchronous step-down switching regulator with fixed 3.3 V output, 4–38 V input range, 30 µA quiescent current in low-consumption mode, peak-current-mode control, and integrated output voltage supervisor. It delivers stable power to microcontrollers and FPGAs in industrial PLCs and decentralized sensor nodes.

For engineers reviewing the L6986H3V3TR datasheet, L6986H3V3TR pinout, L6986H3V3TR application, or L6986H3V3TR equivalent, key selection criteria include its 100% duty-cycle capability (P-channel HS), dual operating modes (LCM/LNM), RST open-collector sequencing support, adjustable soft-start, and synchronization up to 2 MHz.

Technical Context

The L6986H3V3TR implements peak-current-mode control with internal slope compensation, enabling stable regulation across wide load and input ranges. Its P-channel high-side switch enables true 100% duty cycle operation for ultra-low dropout, while the transconductance error amplifier (100 dB gain) and programmable soft-start (via SS/INH pin) ensure controlled startup into precharged outputs.

Two configurable operating modes are implemented via MLF pin strapping: Low Consumption Mode (LCM) optimizes light-load efficiency with pulse-skipping and 30 µA IQ at 3.3 V output; Low Noise Mode (LNM) enforces constant-frequency PWM with <5 mVpp ripple and synchronization capability (275–2200 kHz). The embedded voltage supervisor asserts RST when VOUT falls below 3.008–3.130 V (configurable threshold).

Key Specifications

Parameter	Value and Actual Design Meaning
Output Current	2 A DC continuous - supports compact 12 V/24 V bus conversion without external current boosting
Input Voltage Range	4 V to 38 V - covers automotive, industrial, and telecom supply rails including cold-crank and surge conditions
Quiescent Current (LCM)	30 µA at light load - enables always-on operation in battery-backed or energy-sensitive nodes
Switching Frequency	250 kHz to 2 MHz - selectable via FSW pin strap; higher frequencies reduce inductor size (e.g., 10 µH @ 2 MHz)
R_DS(on) HS / LS	180 mΩ / 150 mΩ - minimizes conduction loss at full load; enables >90% efficiency at 12 V_IN/3.3 V_OUT
Output Voltage Accuracy	±1.5% (3.25–3.35 V) - ensures reliable reset assertion for µC/FPGA power sequencing and brown-out detection
Thermal Shutdown	165 °C with 30 °C hysteresis - protects against sustained overload or poor PCB thermal design
Soft-Start Time	Adjustable via external capacitor on SS/INH - prevents inrush current into large output capacitors (e.g., 200 nF → ~20 ms)

Pinout & Package

Package: HTSSOP-16 (exposed pad), 5 mm × 4.4 mm × 1.2 mm, thermal resistance R_thJA = 40 °C/W (on ST demo board).

Pin/Terminal	Circuit Role	Design Meaning
1 RST	Open-collector reset output	Asserts low when VOUT drops below programmed threshold; used for µC reset or cascaded power sequencing
2 VCC	Analog supply reference	Requires ≥470 nF ceramic bypass; powers internal bandgap and error amplifier
3 SS/INH	Soft-start / inhibit control	Internal 4 µA current source charges external capacitor; clamp to GND disables regulator
4 SYNCH/ISKIP	Mode select & sync input	Configures LCM/LNM and skip level in LCM; accepts external clock for master-slave synchronization
5 FSW	Frequency selection	Pull-up/down resistor sets f_SW (250 kHz–2 MHz); strapping active only before soft-start
6 MLF	Mode & RST threshold select	Resistor divider sets LCM/LNM and RST trip point (e.g., 0 Ω → 93% of 3.3 V = 3.07 V)
7 COMP	Error amplifier output	Connects external RC network for loop compensation; sets phase margin and transient response
8 DELAY	RST deassertion timing	External capacitor sets delay before RST releases after VOUT recovery (e.g., 100 nF → ~120 ms)
9 VOUT	Feedback sense input	Monitors regulated output via internal 0.85 V reference; connects directly to output for fixed 3.3 V version
10 SGND	Signal ground	Reference for analog blocks (error amp, comparators); must be star-connected to minimize noise coupling
11–12 PGND	Power ground (dual)	Carries high di/dt switching currents; tied to exposed pad for thermal and EMI performance
13–14 LX	Switching node (dual)	Connects to external inductor; dual pins reduce trace inductance and improve EMI
15 VIN	Main input supply	Accepts 4–38 V; requires local ceramic + bulk capacitance near pin for stability and surge handling
16 VBIAS	Efficiency-boosting bias supply	Connect to 3.3 V output to reduce IQ by ~50%; improves light-load efficiency in LCM
EP	Exposed thermal pad	Mandatory connection to SGND + PGND plane; primary thermal path to PCB (R_thJC = 5 °C/W)

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 V
Embedded output voltage supervisor	Programmable RST threshold (80–96% of V_OUT) with adjustable delay - eliminates need for external reset IC
Synchronous rectification	Integrated N-channel low-side MOSFET - achieves >92% efficiency at 1 A, 12 V_IN/3.3 V_OUT
Adjustable soft-start	Externally timed via SS/INH capacitor - prevents inrush into ≥1000 µF output banks without external circuitry
Thermal shutdown with hysteresis	165 °C trip, 30 °C hysteresis - avoids thermal oscillation during sustained overload or poor heatsinking
Overvoltage protection (OVP)	1.15×V_REF trip (3.8 V for 3.3 V version) - discharges output capacitor to prevent downstream damage

Applications

Industrial PLC Power Supply

Decentralized Sensor Node

Use Scenario: Powering I/O modules and communication interfaces in DIN-rail mounted programmable logic controllers operating from 24 V DC bus.

IC Role / Device Role / Timing Role: Primary 3.3 V point-of-load regulator delivering 2 A to ARM Cortex-M7 MCU, Ethernet PHY, and isolated CAN transceivers.

Use Value: Wide 4–38 V input handles 24 V bus transients; LCM mode extends standby runtime; RST sequencing coordinates multi-rail startup.

Use Scenario: Compact, low-noise power for battery-assisted field sensors (temperature, pressure, vibration) deployed in harsh industrial environments.

IC Role / Device Role / Timing Role: Main system regulator supplying 3.3 V to ultra-low-power MCU, ADC, and wireless SoC (BLE/Zigbee) with precise brown-out detection.

Use Value: 30 µA LCM IQ enables multi-year battery life; LNM mode suppresses switching noise during ADC sampling; VBIAS switchover cuts total system IQ.

Programmable Logic Controller (PLC) Backplane

Low-Noise Analog Signal Chain

Use Scenario: Distributed power on modular PLC backplanes where multiple L6986H3V3TR units supply individual slots from shared 12 V or 24 V rail.

IC Role / Device Role / Timing Role: Slot-level regulator with synchronized switching (via SYNCH pin) to minimize conducted EMI across backplane traces.

Use Value: Adjustable f_SW allows EMI tuning; ratiometric soft-start (shared CSS) ensures simultaneous rail ramp-up; dual LX pins reduce layout parasitics.

Use Scenario: Powering precision analog front-ends (op-amps, references, SAR ADCs) in test equipment or process analyzers requiring clean 3.3 V.

IC Role / Device Role / Timing Role: Low-noise 3.3 V source operating in LNM mode with fixed 1 MHz f_SW, synchronized to system clock to avoid beat frequencies.

Use Value: Constant-frequency PWM and minimized ripple (<5 mVpp) preserve SNR; internal slope compensation ensures stability with low-ESR ceramic output caps.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM61480RQWR	3.5 A rating, 3–36 V input, 15 µA IQ (shutdown), no integrated RST, requires external compensation	Better suited for higher-current loads; lacks built-in sequencing and supervisor - needs external reset IC and timing circuitry	Select when >2 A output or lower shutdown IQ is critical; accept added BOM cost and layout complexity for supervision
TPS54202HDDCR	2 A, 4.5–17 V input, 26 µA IQ (light load), no LNM mode, no RST, smaller SOT-23-8 package	Restricted to 12 V bus only; no low-noise mode or voltage sequencing - unsuitable for 24 V industrial or FPGA reset coordination	Choose for space-constrained 12 V designs where sequencing and noise immunity are non-critical; verify thermal derating at full load

Compared with LM61480RQWR and TPS54202HDDCR, the L6986H3V3TR uniquely integrates RST-based sequencing, dual LCM/LNM operation, and 100% duty cycle in a single 16-pin HTSSOP - reducing system-level component count and simplifying compliance with industrial power-up timing requirements.

Availability

L6986H3V3TR is available at Aetrix Electronics and suitable for industrial automation, sensor networks, and programmable logic controller designs requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for L6986H3V3TR 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 L6986H series belongs to ST's high-voltage synchronous buck regulator product line, engineered specifically for robust 12 V/24 V bus conversion in programmable logic controllers, industrial I/O modules, and decentralized intelligent nodes.

FAQ

What is the purpose of the VBIAS pin on the L6986H3V3TR?

The VBIAS pin allows connection to the regulated 3.3 V output to power part of the internal analog circuitry, reducing total quiescent current drawn from VIN by up to 50% in Low Consumption Mode. When VBIAS is left unconnected or grounded, the device draws all bias current from VIN. The switchover threshold is 2.78–3.2 V, ensuring seamless transition between sources.

How does the RST pin function in power sequencing applications?

The RST pin is an open-collector output that goes low when VOUT falls below a user-configured threshold (e.g., 3.07 V for 93% setting). It remains asserted for a time set by the DELAY pin capacitor before releasing. This enables cascaded startup: connect RST of a master regulator to SS/INH of a slave to enforce strict power-up order without external timers or logic.

Can the L6986H3V3TR operate with 100% duty cycle, and under what conditions?

Yes - the integrated P-channel high-side MOSFET enables true 100% duty cycle operation, allowing VOUT to remain regulated even when VIN approaches VOUT (e.g., 3.5 V input → 3.3 V output). This occurs automatically in dropout conditions and is confirmed in the datasheet's electrical characteristics table under "Duty cycle" (0–100%). No external components or configuration are required.

What are the key differences between Low Consumption Mode (LCM) and Low Noise Mode (LNM)?

LCM uses pulse-skipping at light loads to achieve 30 µA IQ but introduces variable-frequency operation and higher output ripple. LNM forces constant-frequency PWM (250 kHz–2 MHz) with minimal ripple (<5 mVpp), ideal for noise-sensitive analog circuits, but increases light-load IQ to ~0.5–1.5 mA. Mode selection is set at power-up via MLF pin strapping and cannot be changed dynamically.

L6986H3V3TR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Fixed

Number of Outputs:: 1

Voltage - Input (Min):: 4V

Voltage - Input (Max):: 38V

Voltage - Output (Min/Fixed):: 3.3V

Voltage - Output (Max):: -

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

L6986H3V3TR FAQ

1.How can I place an order for L6986H3V3TR through Aetrix?

Please submit a Request for Quotation (RFQ) for L6986H3V3TR 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 L6986H3V3TR reliable?

The price and inventory of L6986H3V3TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L6986H3V3TR is usually 5 days.

3.What payment methods are accepted for L6986H3V3TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L6986H3V3TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L6986H3V3TR?

L6986H3V3TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L6986H3V3TR 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 L6986H3V3TR?

For technical support, including L6986H3V3TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L6986H3V3TR requirements.

6.How does Aetrix verify that L6986H3V3TR is sourced from the original manufacturer or authorized distributors?

All L6986H3V3TR 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 L6986H3V3TR meets industry standards.

7.What is the process for return or replacement of L6986H3V3TR?

All L6986H3V3TR units undergo pre-shipment inspection (PSI). If there is an issue with L6986H3V3TR, 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 L6986H3V3TR part is unused and in its original packaging.

Return procedure for L6986H3V3TR:

1.Submit a request within 90 days.

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

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