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

STMicroelectronics L6986H

Name: L6986H
Brand: STMicroelectronics
SKU: L6986H
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L6986H

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

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

Datasheet:: L6986H.pdf

Description:: IC REG BUCK ADJ 2A 16HTSSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L6986H from STMicroelectronics is a 2 A synchronous step-down switching regulator with 4 V to 38 V input range, peak current mode control, and dual operating modes (LCM/LNM). It delivers adjustable output from 0.85 V to VIN or fixed 3.3 V/5 V, features embedded voltage supervisor (RST), synchronization capability, and 30 µA quiescent current in low-consumption mode - used in PLC power rails and sensor nodes requiring stable, low-noise DC-DC conversion.

For engineers reviewing the L6986H datasheet, L6986H pinout, L6986H application, or L6986H equivalent, key selection criteria include its 100% duty cycle P-channel high-side switch, RDS(on) values (180 mΩ HS / 150 mΩ LS), adjustable soft-start, overvoltage protection, and configurable reset timing via external DELAY capacitor - critical for FPGA/microcontroller power sequencing and industrial bus compliance.

Technical Context

The L6986H implements a peak current mode architecture with pulse-by-pulse current sensing on both high-side and low-side MOSFETs, enabling precise constant-current protection and foldback under short-circuit. Its P-channel high-side switch enables true 100% duty cycle operation for ultra-low dropout performance.

Two distinct operating modes are selected via MLF pin strapping: Low Consumption Mode (LCM) uses variable-frequency discontinuous conduction to minimize IQ (30 µA at light load), while Low Noise Mode (LNM) enforces fixed-frequency PWM (250 kHz–2 MHz) with synchronized operation across up to six slave devices - meeting stringent ripple and EMI requirements in sensor and analog signal chains.

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	2 A DC - sufficient for powering microcontrollers, FPGAs, and multi-sensor subsystems from a single regulator.
Quiescent Current (LCM)	30 µA at light load (VOUT = 3.3 V) - extends battery life in always-on industrial monitoring nodes.
Switching Frequency	Adjustable 250 kHz to 2 MHz via FSW pin strapping - enables optimization of size (high fSW) vs. efficiency (low fSW).
RDS(on) HS / LS	180 mΩ / 150 mΩ - reduces conduction losses and thermal stress at full load, supporting compact thermal design.
Reset Output (RST)	Open-drain, programmable threshold & delay - provides sequenced power-up for digital loads and system-level reset coordination.
Protection Features	Overvoltage (1.15×VREF), thermal shutdown (165 °C), valley current limit, and pulse-by-pulse current limiting - ensures robust field operation without external supervision.

Pinout & Package

Package: HTSSOP-16 (exposed pad), thermally enhanced for industrial ambient (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 falls below programmed threshold; delay set by external capacitor on PIN 8 - enables power-good signaling and multi-rail sequencing.
2 VCC	Internal analog supply	Requires ≥470 nF ceramic decoupling; powers internal reference and error amplifier - critical for stability and noise immunity.
3 SS/INH	Soft-start/inhibit control	Charged by 4 µA current source for controlled ramp; pulled low to inhibit - prevents inrush current and supports external enable sequencing.
4 SYNCH/ISKIP	Sync input / skip level select	In LNM: accepts external clock (275–2200 kHz); in LCM: selects skip current threshold - enables EMI reduction and light-load efficiency tuning.
5 FSW	Frequency selection	Strapped to VCC or GND with E24 resistors to set fSW from 250 kHz to 2 MHz - determines inductor size and ripple trade-off.
6 MLF	Mode & RST threshold select	Configures LCM/LNM and sets RST trip point (e.g., 93% or 80% of VOUT) - defines system fault response behavior.
7 COMP	Error amplifier output	Connects external compensation network (RC + C) - stabilizes loop dynamics for varied output capacitance and load conditions.
8 DELAY	RST assertion timing	External capacitor sets delay before RST release after VOUT recovery - avoids false resets during transient recovery.
9 FB	Feedback input	Senses output via resistor divider; internal 0.85 V reference - enables adjustable or fixed-output configurations with tight regulation (±1.5%).
10 SGND	Signal ground	Reference for analog blocks (error amp, references); must be star-connected to PGND at single point - minimizes noise coupling.
11–12 PGND	Power ground (dual)	Carries high di/dt switching currents; connects to exposed pad - essential for thermal dissipation and EMI control.
13–14 LX	Switching node (dual)	Connects to external inductor; dual pins reduce parasitic inductance - improves efficiency and reduces voltage spikes.
15 VIN	Main input supply	Accepts 4–38 V; includes UVLO (2.7 V rise / 2.4 V fall) - ensures safe startup and brownout recovery.
16 VBIAS	Bias supply switchover	Connect to regulated VOUT (3–5.5 V) to reduce IQ at VIN - cuts total quiescent draw by shifting internal supply path.
EP	Exposed pad	Must be soldered to SGND+PGND plane - primary thermal path; failure to connect causes thermal shutdown.

Key Features

Feature	Design Value
100% duty cycle operation	P-channel high-side MOSFET enables dropout as low as VOUT − V_{GS(th), critical for 12 V→3.3 V or 24 V→5 V conversion near input rail.}
Programmable reset timing	External DELAY capacitor sets RST assertion delay post-fault - eliminates race conditions in multi-rail systems with different startup times.
Synchronization support	Master/slave sync up to 6 devices with ±5% frequency tolerance - eliminates beat frequencies and simplifies EMI filtering in multi-regulator designs.
Switchover bias supply	VBIAS pin draws internal current from regulated output instead of VIN when connected to 3–5.5 V - reduces effective IQ by >50% in LCM mode.
Pulse-by-pulse current limiting	Monitors HS and LS current each cycle; foldback during hard short protects external MOSFETs and inductor - no external sense resistor required.

Applications

Industrial PLC Power Rails

Sensor Node Power Management

Use Scenario: Powering I/O modules, communication interfaces, and microcontrollers in DIN-rail mounted PLCs fed from 24 V DC bus.

IC Role / Device Role / Timing Role: Primary 5 V or 3.3 V point-of-load regulator with sequencing and reset supervision for CPU/FPGA subsystems.

Use Value: Wide 4–38 V input handles bus transients; 30 µA LCM IQ extends uptime in low-power sleep states; RST output coordinates firmware initialization.

Use Scenario: Supplying low-noise analog front-ends, ADCs, and wireless transceivers in battery-powered environmental sensors.

IC Role / Device Role / Timing Role: Dual-mode DC-DC converter operating in LNM for active measurement cycles and LCM for standby - minimizing ripple and average current draw.

Use Value: Fixed 250–2000 kHz LNM frequency avoids sensitive bands; <1.2% VOUT ripple meets 16-bit ADC PSRR requirements; 8 µA shutdown current preserves battery.

FPGA Core & I/O Rail Sequencing

Decentralized Intelligent Node (DIN)

Use Scenario: Generating multiple tightly sequenced voltages (e.g., 1.2 V core, 2.5 V I/O, 3.3 V aux) for Xilinx/Intel FPGAs in industrial controllers.

IC Role / Device Role / Timing Role: Master regulator using RST-to-SS/INH chaining to control slave converters - enforcing strict power-up order per FPGA vendor spec.

Use Value: Adjustable DELAY capacitor ensures 10–100 ms inter-rail delays; ±1.5% output accuracy maintains FPGA configuration integrity.

Use Scenario: Powering edge-computing nodes with ARM Cortex-M MCUs, CAN transceivers, and local IO in factory automation networks.

IC Role / Device Role / Timing Role: Central 3.3 V supply with integrated voltage supervisor and sync input - enabling coordinated wake-up and deterministic timing across distributed nodes.

Use Value: Synchronization to central clock eliminates jitter in time-sensitive protocols; thermal shutdown (165 °C) ensures reliability in enclosed enclosures.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM5164QPWPRQ1	40 V max input, 0.6 A output, integrated FETs but lower current rating; no RST output or DELAY programmability.	Lacks built-in sequencing and supervisor functions - requires external reset IC and timing circuitry for FPGA/PLC use.	Select only if output current ≤0.6 A and sequencing is handled externally; not drop-in for L6986H's 2 A + RST role.
TPS54202DRCT	28 V max input, 2 A output, similar pinout but no LNM/LCM mode selection; fixed 500 kHz fSW; no VBIAS switchover.	Higher IQ (40 µA typical) and no programmable reset - less suitable for battery-backed or low-noise sensor nodes.	Choose when cost sensitivity outweighs light-load efficiency and sequencing needs; verify thermal margin at 38 V input.

Compared with LM5164QPWPRQ1 and TPS54202DRCT, the L6986H uniquely integrates 2 A capability, dual LCM/LNM operation, programmable RST with delay, and VBIAS switchover - making it the only option among the three that satisfies full industrial PLC power sequencing and ultra-low-IQ sensor node requirements simultaneously.

Availability

L6986H is available at Aetrix Electronics and suitable for industrial PLCs, decentralized intelligent nodes, sensor signal chains, and FPGA power management requiring stable component supply across extended temperature and long product lifecycles.

Supply support for L6986H 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 automotive-grade ICs with ISO 9001 and IATF 16949 certified manufacturing.

The L6986H belongs to ST's high-voltage synchronous buck regulator family, designed specifically for rugged industrial power conversion where wide input range, low IQ, and integrated supervision are mandatory - not general-purpose DC-DC conversion.

FAQ

What is the minimum input voltage required for L6986H to start switching?

The L6986H begins operation when VIN exceeds the VCC UVLO rising threshold of 2.7 V (typical), but functional regulation requires VIN ≥ 4 V per datasheet specification. Below 4 V, output voltage cannot be maintained across load and line variations, even if the IC powers up internally.

Can L6986H operate with 100% duty cycle, and under what conditions?

Yes - the P-channel high-side MOSFET enables true 100% duty cycle operation when VOUT is close to VIN (e.g., 12 V input → 11.5 V output), allowing dropout as low as V_{GS(th). This occurs only in continuous conduction mode with light load and no current limit activation.}

How does the VBIAS pin reduce quiescent current?

When VBIAS is connected to a regulated 3–5.5 V source (e.g., VOUT), the internal pre-regulator switches its supply path from VIN to VBIAS, reducing the effective IQ drawn from the main input. In LCM mode, this cuts total VIN current from ~70 µA to ~30 µA at light load.

Is synchronization supported in both LCM and LNM modes?

No - synchronization is only active in Low Noise Mode (LNM). In LCM, the SYNCH pin functions as ISKIP for setting skip-current thresholds. Attempting to drive an external clock into SYNCH during LCM has no effect and may cause undefined behavior per datasheet Section 2.2.

L6986H 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

L6986H FAQ

1.How can I place an order for L6986H through Aetrix?

Please submit a Request for Quotation (RFQ) for L6986H 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 L6986H reliable?

The price and inventory of L6986H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L6986H is usually 5 days.

3.What payment methods are accepted for L6986H?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L6986H transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L6986H?

L6986H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L6986H 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 L6986H?

For technical support, including L6986H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L6986H requirements.

6.How does Aetrix verify that L6986H is sourced from the original manufacturer or authorized distributors?

All L6986H 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 L6986H meets industry standards.

7.What is the process for return or replacement of L6986H?

All L6986H units undergo pre-shipment inspection (PSI). If there is an issue with L6986H, 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 L6986H part is unused and in its original packaging.

Return procedure for L6986H:

1.Submit a request within 90 days.

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

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