Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

STMicroelectronics L4973D5.1-013TR

Name: L4973D5.1-013TR
Brand: STMicroelectronics
SKU: L4973D5.1-013TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: L4973D5.1-013TR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 20-SOIC (0.295", 7.50mm Width)

Datasheet:: L4973D5.1-013TR.pdf

Description:: IC REG BUCK ADJ/5.1V 3.5A 20SO

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:2,307

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

L4973D5.1-013TR from STMicroelectronics is a monolithic step-down switching regulator delivering up to 3.5 A at a fixed 5.1 V ±1% output, operating from 8 V to 55 V input, featuring internal D-MOS with R_DS(on) = 0.15 Ω (typ), adjustable frequency up to 300 kHz, and integrated soft-start, thermal shutdown, and overvoltage protection - deployed in industrial power supplies and automotive body control modules.

For engineers reviewing the L4973D5.1-013TR datasheet, L4973D5.1-013TR pinout, L4973D5.1-013TR application, or L4973D5.1-013TR equivalent, key selection criteria include input voltage range (8–55 V), output current capability (3.5 A), fixed 5.1 V regulation accuracy (±1%), SO-20 package thermal resistance (R_thJA = 80 °C/W), and synchronization support for multi-rail systems.

Technical Context

The L4973D5.1-013TR implements voltage-mode PWM control with feed-forward compensation, enabling stable regulation across wide input variations. Its internal error amplifier provides 60 dB open-loop gain and 2.5 mS transconductance, while the oscillator supports external R/C programming (90–300 kHz) and automatic line feed-forward via OSC pin configuration.

Protection architecture includes pulse-by-pulse current limiting (4.5 A typ), hiccup-mode short-circuit response, feedback disconnection detection, and thermal shutdown at 150 °C. The device supports zero-load operation (2.7 mA quiescent current) and deep sleep mode (<200 µA standby at V_CC = 24 V) via active-high INH pin.

Key Specifications

Parameter	Value and Actual Design Meaning
Output voltage	Fixed 5.1 V ±1% - ensures stable logic supply for microcontrollers and sensors without external feedback divider.
Max output current	3.5 A continuous - supports high-current loads like motor drivers or LED arrays without external pass devices.
Input voltage range	8 V to 55 V - accommodates 12 V/24 V/48 V industrial and automotive battery systems with transient tolerance.
Switching frequency	Adjustable 90–300 kHz - enables optimization of inductor size vs. EMI; 100 kHz typical for efficiency, 200 kHz for compact designs.
R_DS(on)	0.15 Ω (typ) - minimizes conduction loss, enabling >90% efficiency at 5.1 V/3.5 A with proper heatsinking.
Reference voltage	5.1 V ±1.5% externally available at V5.1 pin - usable as precision bias source for external circuitry or ADC reference.
Quiescent current	4 mA (operating), 100 µA (standby) - supports low-power modes in battery-backed or always-on systems.
Thermal shutdown	150 °C junction temperature - protects against sustained overload or inadequate PCB copper area.

Pinout & Package

Package: SO-20 (12+4+4) surface-mount package with exposed thermal pad (R_thJA = 80 °C/W, R_thJP = 15 °C/W); requires minimum 200 mm² copper pour under exposed pad for thermal performance.

Pin/Terminal	Circuit Role	Design Meaning
1, 20	OSC / SYNC	Configurable oscillator/synchronization node - sets switching frequency with external R/C or synchronizes to master clock.
2, 3	OUT	Main power output - connects directly to LC filter; dual pins reduce trace resistance and improve current sharing.
4–7, 14–17	GND	Signal and power ground - 12 dedicated GND pins ensure low-impedance return path and minimize noise coupling.
8, 9	VCC	Unregulated input supply - powers internal circuitry; must be decoupled with ≥10 µF ceramic near pins.
10	INH	Inhibit control - active-high logic disables switching and reduces current to <200 µA; floating = disabled.
11	COMP	Error amplifier output - connects to external compensation network (typically RC + capacitor) for loop stability.
12	VFB	Feedback input - internally referenced to 5.1 V; direct connection yields 5.1 V output; resistive divider enables higher voltages.
13	V5.1	Precision 5.1 V reference output - buffered, loadable up to 20 mA; used for external bias or calibration.
18	SS	Soft-start capacitor node - controls ramp-up time of output voltage; prevents inrush current during startup.
19	BOOT	Bootstrap driver supply - capacitor between BOOT and OUT enables high-side gate drive for internal D-MOS.

Key Features

Feature	Design Value
Voltage feed-forward regulation	Compensates for input ripple in real time, reducing output voltage deviation during line transients by >60 dB @ 100 Hz.
Pulse-by-pulse current limiting	Monitors peak switch current each cycle; limits to 4.5 A typ, preventing MOSFET failure during short-circuit events.
Hiccup-mode short-circuit protection	Enters auto-retry after fault clearance - avoids thermal runaway while maintaining system visibility of fault condition.
Zero-load operation	Maintains regulation down to 1 mA load with only 4 mA quiescent current - suitable for standby power rails.
Input/output synchronization	SYNC pin operates as bidirectional interface - allows multiple L4973s to share common clock, eliminating beat-frequency EMI.
Protection against feedback disconnection	Detects open VFB loop and forces shutdown - prevents uncontrolled output overvoltage in case of resistor failure or solder void.

Applications

Industrial PLC Power Supply

Automotive Body Control Module

Use Scenario: Converts 24 V vehicle battery to stable 5.1 V for MCU, CAN transceivers, and sensor interfaces in door modules or lighting controllers.

IC Role / Device Role / Timing Role: Primary buck regulator supplying core logic voltage; synchronized to chassis clock to suppress EMI in EMC-sensitive zones.

Use Value: 3.5 A capacity supports concurrent operation of multiple peripherals; 8–55 V input range tolerates cold-crank (6.5 V) and load-dump (60 V) transients per ISO 7637-2.

Use Scenario: Powers I/O expansion cards in programmable logic controllers requiring clean, high-current 5.1 V rail under variable 24 V factory supply.

IC Role / Device Role / Timing Role: Main DC-DC converter with soft-start and hiccup protection - ensures reliable startup during hot-swap insertion and fault recovery.

Use Value: Internal 0.15 Ω R_DS(on) and 90% efficiency at full load reduce thermal stress on densely packed backplanes; SO-20 footprint simplifies layout and rework.

Telecom Remote Radio Unit

Medical Diagnostic Equipment

Use Scenario: Generates 5.1 V from 48 V PoE-derived input for FPGA configuration, ADC bias, and RF front-end ICs in outdoor base stations.

IC Role / Device Role / Timing Role: High-efficiency intermediate bus converter; frequency synchronized to system clock to avoid spectral interference with RF bands.

Use Value: Adjustable 90–300 kHz switching enables EMI filtering below 150 kHz CISPR-32 limits; 5.1 V ±1% accuracy ensures consistent ADC reference and digital logic margins.

Use Scenario: Supplies isolated 5.1 V logic rail for patient-monitoring front-end ASICs where low noise and reliability are critical.

IC Role / Device Role / Timing Role: Regulated power source with thermal shutdown and overvoltage protection - meets IEC 60601-1 safety requirements for fault containment.

Use Value: Zero-load operation and <200 µA standby current extend battery life in portable diagnostics; precise V5.1 reference improves analog signal chain accuracy.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM2596S-5.0/NOPB	Fixed 5.0 V output, 3 A max, 150 kHz fixed frequency, no sync or feed-forward.	Lacks synchronization, hiccup protection, and wide-input capability (4.5–40 V only).	Choose for cost-sensitive, non-safety-critical 5 V rails where 3 A suffices and EMI constraints are relaxed.
MP2451DT-LF-Z	Fixed 5.0 V, 2 A, 2 MHz switching, smaller SO-8 package, no V5.1 reference output.	Higher frequency enables tiny inductors but sacrifices efficiency above 24 V input and lacks precision reference.	Prefer for space-constrained consumer electronics; avoid where >3 A or 5.1 V accuracy is required.

Compared with LM2596S-5.0/NOPB and MP2451DT-LF-Z, the L4973D5.1-013TR delivers higher current (3.5 A), tighter output tolerance (±1% vs. ±2%), wider input range (8–55 V), and unique features including external 5.1 V reference, feed-forward regulation, and robust hiccup-mode protection - making it suitable for demanding industrial and automotive applications where reliability and design margin are critical.

Availability

L4973D5.1-013TR is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control modules, telecom remote radio units, and medical diagnostic equipment requiring stable component supply across extended temperature and voltage ranges.

Supply support for L4973D5.1-013TR 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, Switzerland, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The L4973 series belongs to ST's high-voltage DC-DC converter product line, engineered specifically for rugged 8–55 V input environments in automotive and industrial applications where efficiency, thermal resilience, and integrated protection are essential.

FAQ

What is the maximum recommended PCB copper area for thermal management of the L4973D5.1-013TR?

The SO-20 package requires ≥200 mm² of 2-oz copper connected to the 12 GND pins and exposed thermal pad. ST recommends using thermal vias (≥8 × 0.3 mm diameter) to inner-layer ground planes to achieve R_thJA ≤ 80 °C/W. Without adequate copper, thermal shutdown may trigger at <2.5 A continuous load.

Can the L4973D5.1-013TR regulate output voltages lower than 5.1 V?

No - the L4973D5.1-013TR is factory-trimmed for fixed 5.1 V output. For outputs below 5.1 V, ST specifies the L4973D3.3-013TR variant (3.3 V). Attempting to force lower voltage via external feedback violates internal reference architecture and risks instability or overvoltage protection activation.

How does the SYNC pin function in master-slave configurations?

The SYNC pin operates bidirectionally: when driven externally (e.g., by another L4973 or clock generator), it overrides internal oscillator timing; when left unconnected, it sources a 5 V logic-level square wave at the configured switching frequency, enabling synchronization of up to four slave regulators without external clock distribution.

Is the V5.1 reference pin intended for use as a system-wide precision voltage source?

Yes - Pin 18 (V5.1) provides a buffered, temperature-compensated 5.1 V ±1.5% reference capable of sourcing up to 20 mA. It is electrically isolated from the main output and can supply ADC references, sensor excitation, or comparator thresholds without affecting regulation accuracy or stability.

L4973D5.1-013TR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 20-SOIC (0.295", 7.50mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Adjustable (Fixed)

Number of Outputs:: 1

Voltage - Input (Min):: 8V

Voltage - Input (Max):: 55V

Voltage - Output (Min/Fixed):: 5.1V (5.1V)

Voltage - Output (Max):: 50V

Current - Output:: 3.5A

Frequency - Switching:: 100kHz ~ 300kHz

Synchronous Rectifier:: No

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-SO

L4973D5.1-013TR FAQ

1.How can I place an order for L4973D5.1-013TR through Aetrix?

Please submit a Request for Quotation (RFQ) for L4973D5.1-013TR 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 L4973D5.1-013TR reliable?

The price and inventory of L4973D5.1-013TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L4973D5.1-013TR is usually 5 days.

3.What payment methods are accepted for L4973D5.1-013TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L4973D5.1-013TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L4973D5.1-013TR?

L4973D5.1-013TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L4973D5.1-013TR 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 L4973D5.1-013TR?

For technical support, including L4973D5.1-013TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L4973D5.1-013TR requirements.

6.How does Aetrix verify that L4973D5.1-013TR is sourced from the original manufacturer or authorized distributors?

All L4973D5.1-013TR 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 L4973D5.1-013TR meets industry standards.

7.What is the process for return or replacement of L4973D5.1-013TR?

All L4973D5.1-013TR units undergo pre-shipment inspection (PSI). If there is an issue with L4973D5.1-013TR, 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 L4973D5.1-013TR part is unused and in its original packaging.

Return procedure for L4973D5.1-013TR:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-03 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-01 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…