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

STMicroelectronics L7987L

Name: L7987L
Brand: STMicroelectronics
SKU: L7987L
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L7987L

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 16-TSSOP (0.173", 4.40mm Width) Exposed Pad

Datasheet:: L7987L.pdf

Description:: IC REG BUCK ADJ 2A 16HTSSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L7987L from STMicroelectronics is a 61 V, 2 A asynchronous step-down switching regulator with adjustable current limitation, designed for industrial DC-DC conversion in 24 V bus systems. It delivers up to 2 A DC output current, supports 4.5–61 V input range, features 300 mΩ typical high-side R_DS(on), and enables output voltage adjustment from 0.8 V to near VIN - used in programmable logic controllers (PLCs) and fail-safe tolerant power supplies.

For engineers reviewing the L7987L datasheet, L7987L pinout, L7987L application, or L7987L equivalent, key selection criteria include its adjustable switching frequency (250 kHz–1.5 MHz), PGOOD open-collector output for sequencing, digital frequency foldback under short-circuit, and VBIAS-assisted light-load efficiency optimization.

Technical Context

The L7987L implements a voltage-mode control loop with fixed-frequency PWM, where the COMP pin carries the error amplifier output compared against a sawtooth ramp generated by an integrated oscillator. Input voltage feed-forward adjusts ramp slope to maintain constant PWM gain across VIN variations.

It integrates pulse-by-pulse peak current sensing with programmable ILIM threshold, digital frequency foldback during overcurrent, and peak current foldback in heavy short-circuit - all coordinated with thermal shutdown at 170 °C and 15 °C hysteresis. Synchronization via SYNCH pin supports master/slave operation up to five devices.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4.5 V to 61 V - supports wide industrial bus rails including 24 V and 48 V systems without external pre-regulation.
Output Current	2 A DC continuous - sufficient for powering microcontrollers, I/O drivers, and sensor interfaces in PLC modules.
Switching Frequency	250 kHz to 1.5 MHz (adjustable via FSW resistor) - enables compact magnetics and noise-sensitive layout optimization.
R_DS(on)	300 mΩ typ. (HS MOSFET) - reduces conduction loss and thermal stress at full load in high-VIN applications.
Quiescent Current	11 µA typ. in shutdown, 1 mA typ. at 24 V_IN/3.3 V_OUT - extends standby runtime in always-on industrial nodes.
Feedback Reference	0.800 V ±1% - enables precise output regulation and stable compensation network design with standard resistive dividers.
PGOOD Threshold	70% of target V_OUT (0.70 V at FB) with 30 mV hysteresis - ensures reliable power sequencing and fault detection in multi-rail systems.

Pinout & Package

Package: HTSSOP16 (exposed pad), thermal resistance R_thJA = 40 °C/W on ST reference board.

Pin/Terminal	Circuit Role	Design Meaning
1 VBIAS	Auxiliary supply input	Connects to regulated output or ≥3 V rail to power analog circuitry, reducing quiescent current and improving light-load efficiency.
2,3 VIN	Main power input	Dual pins reduce trace resistance and improve current handling for high-input-voltage industrial applications.
4 VCC	Internal bias supply	Bypassed with 1 µF ceramic capacitor; powers internal logic and references before VBIAS switchover occurs.
5 EN	Enable control	Active-high logic input; internal pull-down ensures safe default-off state when floating.
6 SS	Soft-start timing	5 µA internal current source charges external capacitor to control monotonic V_OUT ramp and limit inrush.
7 SYNCH	Synchronization interface	Master/slave clock signal (180° phase shift); supports up to five synchronized converters to reduce input ripple RMS current.
8 COMP	Error amplifier output	Connects to external Type II/III compensation network; provides direct access to control loop dynamics.
9 FB	Voltage feedback input	Inverting input referenced to 0.8 V internal bandgap; sets output voltage via resistive divider from V_OUT.
10 FSW	Frequency programming	Pull-down resistor selects switching frequency from 250 kHz to 1.5 MHz; floating defaults to 250 kHz.
11 ILIM	Current limit setting	Pull-down resistor programs peak switch current (e.g., 0.85 A typ. with 100 kΩ) to match inductor RMS rating.
12 PGOOD	Power-good indicator	Open-drain output pulled low when FB voltage falls below 70% of target - used for sequencing and system monitoring.
13,14 LX	Power switch node	High-current switching node connecting internal HS MOSFET drain and external bootstrap/inductor path.
15 BOOT	Bootstrap supply	100 nF capacitor between BOOT and LX provides gate drive voltage for internal N-channel HS MOSFET.
16 GND	Signal ground	Exposed pad must be soldered to PCB ground plane for thermal and EMI performance; primary return for analog/digital blocks.

Key Features

Feature	Design Value
Adjustable current limitation	Programmable peak switch current (0.68–3.05 A) via ILIM resistor - allows precise inductor sizing and overload protection tuning.
Advanced bootstrap management	Integrated low-side MOSFET discharges boot capacitor only when needed - prevents premature gate drive collapse during light-load pulse-skipping.
VBIAS-assisted efficiency	Automatic switchover from VCC to VBIAS supply at light load - reduces IQ from 1 mA to 1.6–2.4 mA (VBIAS sourced) for >30% efficiency gain at 10% load.
Digital frequency foldback	Reduces f_SW under short-circuit while maintaining constant current - limits average power dissipation and avoids thermal runaway.
Output voltage sequencing	PGOOD open-collector output enables controlled power-up order across multiple rails using external pull-up and enable chaining.

Applications

Industrial PLC Power Supply

24 V Bus Point-of-Load Converter

Use Scenario: Powering CPU, I/O modules, and fieldbus transceivers in modular programmable logic controllers operating from 24 V DC industrial bus.

IC Role / Device Role / Timing Role: Primary non-isolated buck regulator delivering 3.3 V/2 A or 5 V/2 A with tight regulation and sequencing capability.

Use Value: Adjustable current limit and PGOOD support safe hot-swap insertion and coordinated startup of backplane-mounted modules.

Use Scenario: Local DC-DC conversion for sensors, actuators, and communication ICs distributed across factory automation equipment powered by centralized 24 V bus.

IC Role / Device Role / Timing Role: Compact, thermally robust step-down regulator enabling high-density PCB layouts with minimal external components.

Use Value: 1.5 MHz max switching frequency allows use of ≤2.2 µH inductors, reducing solution size by >40% vs. 500 kHz alternatives.

Fail-Safe System Power

Multi-Converter Synchronized Rail

Use Scenario: Providing redundant or monitored power to safety-critical subsystems such as emergency stop controllers or valve positioners.

IC Role / Device Role / Timing Role: Regulator with thermal shutdown, overcurrent foldback, and PGOOD monitoring - integral to functional safety architecture.

Use Value: Digital frequency foldback and peak current foldback ensure predictable fault behavior during short-circuit, simplifying safety validation.

Use Scenario: Generating multiple synchronized low-noise rails (e.g., 3.3 V, 5 V, 12 V) for mixed-signal systems like industrial data acquisition units with ADCs.

IC Role / Device Role / Timing Role: Master/slave synchronizable buck controller minimizing beat frequencies and input capacitor RMS current in multi-rail designs.

Use Value: Up to five L7987L devices synchronized on one SYNCH line reduce input ripple by ~70%, lowering EMI filter requirements.

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	4.5–65 V input, 1 A output, integrated FET, no VBIAS pin, lower IQ (6 µA shutdown)	Automotive AEC-Q100 qualified; lacks adjustable current limit and PGOOD sequencing capability	Preferred for automotive environments requiring qualification; not suitable for 2 A industrial loads or sequencing-critical PLCs
MP2451DT-LF-Z	4.5–36 V input, 0.6 A output, fixed 2.2 MHz f_SW, no synchronization or VBIAS support	Cost-optimized consumer-grade part; limited thermal margin above 24 V input	Only viable for sub-1 A, non-safety-critical applications; cannot replace L7987L in 2 A/61 V industrial designs

Compared with LM5164QDDARQ1 and MP2451DT-LF-Z, the L7987L uniquely combines 2 A capability, 61 V rating, VBIAS efficiency boost, PGOOD sequencing, and multi-device synchronization - making it the sole fit for high-reliability 24 V bus power in industrial control hardware.

Availability

L7987L is available at Aetrix Electronics and suitable for industrial PLC power supplies, 24 V bus point-of-load conversion, and fail-safe system power requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for L7987L 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 industrial analog solutions.

The L7987L belongs to ST's high-voltage industrial DC-DC regulator product line, engineered specifically for robust, efficient, and configurable power conversion in harsh 24–48 V industrial environments.

FAQ

What is the minimum recommended output capacitor for stable operation?

The L7987L requires a minimum 22 µF ceramic output capacitor with ≤5 mΩ ESR for stability across all operating conditions. ST recommends X7R dielectric with 10 V or higher rating; larger values (47–100 µF) improve transient response and reduce output ripple below 20 mV_PP at full load.

How does the VBIAS pin improve light-load efficiency?

VBIAS supplies the internal analog circuitry instead of VCC when enabled, reducing quiescent current from 1 mA (VCC-sourced) to 1.6–2.4 mA (VBIAS-sourced) at light load. This switchover occurs automatically when VBIAS exceeds 2.9 V, cutting total power loss by up to 35% at 10% load in 24 V→3.3 V conversions.

Can the L7987L operate in dropout mode when VIN approaches VOUT?

Yes - when VIN drops near VOUT, the L7987L enters low-dropout mode by limiting high-side on-time to T_ONMAX = 12 µs, ensuring continuous boot capacitor recharge and regulation down to VIN – VOUT ≈ 1.5 V. This maintains output stability without external LDO supplementation.

What is the maximum number of L7987L devices that can share one SYNCH line?

Up to five L7987L devices can be synchronized on a single SYNCH net. The highest-frequency device becomes master; others lock to its frequency with 180° phase shift. ST validates this configuration for reduced input ripple RMS current and elimination of beat frequencies in multi-rail sensor systems.

L7987L Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 16-TSSOP (0.173", 4.40mm 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):: 61V

Voltage - Output (Min/Fixed):: 0.8V

Voltage - Output (Max):: 61V

Current - Output:: 2A

Frequency - Switching:: 250kHz ~ 1.5MHz

Synchronous Rectifier:: No

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-HTSSOP

L7987L FAQ

1.How can I place an order for L7987L through Aetrix?

Please submit a Request for Quotation (RFQ) for L7987L 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 L7987L reliable?

The price and inventory of L7987L are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L7987L is usually 5 days.

3.What payment methods are accepted for L7987L?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L7987L transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L7987L?

L7987L orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L7987L 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 L7987L?

For technical support, including L7987L datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L7987L requirements.

6.How does Aetrix verify that L7987L is sourced from the original manufacturer or authorized distributors?

All L7987L 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 L7987L meets industry standards.

7.What is the process for return or replacement of L7987L?

All L7987L units undergo pre-shipment inspection (PSI). If there is an issue with L7987L, 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 L7987L part is unused and in its original packaging.

Return procedure for L7987L:

1.Submit a request within 90 days.

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

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