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

STMicroelectronics L4973D3.3-013TR

Name: L4973D3.3-013TR
Brand: STMicroelectronics
SKU: L4973D3.3-013TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L4973D3.3-013TR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

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

Datasheet:: L4973D3.3-013TR.pdf

Description:: IC REG BUCK ADJ/0.5V 3.5A 20SO

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L4973D3.3-013TR from STMicroelectronics is a monolithic 3.5 A step-down switching regulator with fixed 3.3 V ±1 % output, 8–55 V input range, internal 0.15 Ω D-MOS switch, and SO-20 (12+4+4) SMD package. It delivers high-efficiency DC-DC conversion in industrial power supplies, automotive body electronics, and telecom front-end rails.

For engineers reviewing the L4973D3.3-013TR datasheet, L4973D3.3-013TR pinout, L4973D3.3-013TR application, or L4973D3.3-013TR equivalent, key selection criteria include output current capability (3.5 A), input voltage tolerance (up to 55 V), thermal shutdown behavior, soft-start timing control, and feedback disconnection protection.

Technical Context

The L4973D3.3-013TR integrates a BCD-technology D-MOS power switch with typical R_DS(on) of 0.15 Ω and supports adjustable switching frequency up to 300 kHz via external R-C oscillator network. Its voltage feed-forward architecture improves line regulation across wide input swings.

It features dual-stage current limiting-pulse-by-pulse for transient overload and hiccup mode for sustained short-circuit conditions-and includes an externally accessible 5.1 V reference (±1.5 %) for auxiliary circuitry or precision feedback scaling.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.3 V ±1 % - ensures stable logic rail generation without external resistor divider.
Max Output Current	3.5 A continuous - supports high-current microcontroller or FPGA core supplies.
Input Voltage Range	8 V to 55 V - accommodates 12 V/24 V/48 V industrial and automotive battery systems.
R_DS(on)	0.15 Ω typ. - minimizes conduction loss and enables >85 % efficiency at 3.3 V/3.5 A.
Switching Frequency	Adjustable up to 300 kHz - balances EMI control, inductor size, and MOSFET switching loss.
Quiescent Current	2.7–4 mA (operating), 100–300 µA (standby) - enables low-power sleep modes in always-on systems.
Reference Voltage	5.1 V ±1.5 % on Pin 18 - provides accurate bias for external comparators or ADC references.

Pinout & Package

Package: SO-20 (12+4+4) surface-mount package with exposed thermal pad (ECOPACK-compliant); dimensions per ST DocID1546 Rev 19 Table 5.

Pin/Terminal	Circuit Role	Design Meaning
1	OSC	RC oscillator node - sets switching frequency; internal feed-forward path enabled automatically.
2,3	OUT	Main power output terminals - connect to LC filter and load; share internal D-MOS source/drain path.
4–7,14–17	GND	Signal ground pins - multiple dedicated GNDs reduce noise coupling and improve stability.
8,9	VCC	Unregulated input supply - powers internal logic and gate driver; must be ≥8 V and ≤55 V.
10	INH	Inhibit control - active-high logic disables regulator and reduces quiescent current to ~100 µA.
11	COMP	Error amplifier output - connects to external compensation network (type II/III) for loop stability.
12	VFB	Feedback input - tied directly to output for 3.3 V operation; open-loop gain >50 dB ensures tight regulation.
13	BOOT	Bootstrap capacitor connection - drives internal high-side gate; requires 10–100 nF ceramic capacitor.
18	V5.1	5.1 V reference output - buffered, ±1.5 % accuracy; usable as precision reference for external circuits.
19,20	SYNC	Synchronization I/O - allows master-slave clock alignment to reduce system-level EMI peaks.
20	SS	Soft-start capacitor node - controls ramp-up time; typical 100 nF yields ~10 ms startup delay.

Key Features

Feature	Design Value
Voltage feed-forward regulation	Reduces line regulation error to <10 mV over full 8–55 V input range - eliminates need for post-regulation LDOs.
Pulse-by-pulse + hiccup current limiting	Enables safe operation under momentary overload (e.g., motor start) and indefinite short-circuit without thermal runaway.
Zero-load operation down to 1 mA	Maintains regulation with no minimum load - simplifies design for variable-duty-cycle applications like sensor nodes.
Thermal shutdown with hysteresis	Triggers at T_J ≈ 150 °C and releases at ~135 °C - prevents repeated cycling during sustained overheating.
Protection against feedback disconnection	Detects open VFB and forces shutdown - avoids dangerous overvoltage events if feedback trace is severed.

Applications

Industrial PLC Power Rail

Automotive Body Control Module

Use Scenario: Provides 3.3 V core supply for ARM Cortex-M7 MCU and CAN transceivers in programmable logic controllers.

IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 3.3 V at up to 3.5 A with fast transient response to CPU burst loads.

Use Value: Input voltage range (8–55 V) tolerates 24 V battery transients (ISO 7637-2 Pulse 5a); hiccup mode prevents field failures during solenoid coil shorts.

Use Scenario: Powers infotainment SoC and LIN gateway ICs in vehicle door modules with 12 V battery input.

IC Role / Device Role / Timing Role: Fixed-output step-down regulator with soft-start and inhibit control for controlled power sequencing.

Use Value: Standby current <300 µA at 55 V enables compliance with automotive "parking mode" leakage budgets; SYNC pin aligns switching with main ECU clock.

Telecom Remote Radio Unit

Medical Diagnostic Imaging Interface

Use Scenario: Generates 3.3 V supply for RF front-end FEMs and ADCs in 4G/5G small-cell base stations powered from -48 V DC.

IC Role / Device Role / Timing Role: High-efficiency buck stage converting intermediate 24 V rail to clean 3.3 V logic voltage.

Use Value: 85 % efficiency at 3.3 V/3.5 A reduces thermal load in sealed enclosures; R_DS(on) = 0.15 Ω limits conduction loss in high-ambient environments.

Use Scenario: Supplies isolated 3.3 V logic rail for X-ray detector interface ASICs requiring ultra-low noise and high reliability.

IC Role / Device Role / Timing Role: Regulated power source with output overvoltage protection and thermal shutdown for safety-critical subsystems.

Use Value: Output OVP clamps voltage to safe level (<4.5 V) if feedback fails; 15 °C/W junction-to-pin thermal resistance enables direct heatsink mounting.

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-3.3/NOPB	3 A max output, 40 V max input, no sync or hiccup mode, lower integration (external MOSFET required).	Limited to lower-power applications; lacks feedback disconnect protection and precise 5.1 V reference.	Choose when cost sensitivity outweighs robustness requirements and input voltage stays <40 V.
MP2451DT-LF-Z	2 A max output, 36 V max input, 2 MHz fixed frequency, no adjustable frequency or external reference.	Better for compact PCBs needing high-frequency operation but unsuitable for >36 V inputs or multi-rail reference sharing.	Prefer for space-constrained designs where 2 A suffices and 36 V input ceiling is acceptable.

Compared with LM2596S-3.3/NOPB and MP2451DT-LF-Z, the L4973D3.3-013TR offers higher current (3.5 A), wider input (55 V), integrated protection features, and a precision 5.1 V reference - making it uniquely suited for ruggedized industrial and automotive power rails where reliability and flexibility are critical.

Availability

L4973D3.3-013TR is available at Aetrix Electronics and suitable for industrial PLC power rails, automotive body control modules, telecom remote radio units, and medical diagnostic imaging interfaces requiring stable component supply across extended temperature and voltage ranges.

Supply support for L4973D3.3-013TR 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, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The L4973 series belongs to ST's high-voltage monolithic DC-DC converter product line, engineered specifically for robust, high-current buck regulation in harsh environments with wide input voltage variation and stringent reliability demands.

FAQ

What is the maximum allowable input voltage for L4973D3.3-013TR?

The absolute maximum input voltage is 58 V, but continuous operation is rated up to 55 V per ST's production data. Exceeding 55 V risks exceeding internal power dissipation limits and triggering thermal shutdown. For reliable long-term use, maintain V_IN ≤ 55 V with appropriate derating at elevated ambient temperatures.

Can L4973D3.3-013TR operate with zero output load?

Yes - it supports zero-load operation down to 1 mA quiescent current, maintaining regulation without external dummy loads. This is enabled by its internal current-sense architecture and low-power bias design, verified across -40 °C to +125 °C junction temperature range.

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

The SYNC pin operates as both input and output: in slave mode, it accepts external clock signals (3.5 V high, 0.9 V low thresholds); in master mode, it outputs synchronized pulses (4–4.5 V amplitude, 0.2–0.35 µs width) to align switching edges across multiple regulators and suppress beat frequencies in multi-rail systems.

Is external compensation required for stable operation?

Yes - the COMP pin requires an external type II or type III compensation network (typically RC + C network) connected between COMP and GND/VFB to ensure phase margin >45° across all operating conditions. ST Application Note AN938 provides validated component values based on inductor value, output capacitance, and target crossover frequency.

L4973D3.3-013TR 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):: 0.5V (3.3V)

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

L4973D3.3-013TR FAQ

1.How can I place an order for L4973D3.3-013TR through Aetrix?

Please submit a Request for Quotation (RFQ) for L4973D3.3-013TR 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 L4973D3.3-013TR reliable?

The price and inventory of L4973D3.3-013TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L4973D3.3-013TR is usually 5 days.

3.What payment methods are accepted for L4973D3.3-013TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L4973D3.3-013TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L4973D3.3-013TR?

L4973D3.3-013TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L4973D3.3-013TR 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 L4973D3.3-013TR?

For technical support, including L4973D3.3-013TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L4973D3.3-013TR requirements.

6.How does Aetrix verify that L4973D3.3-013TR is sourced from the original manufacturer or authorized distributors?

All L4973D3.3-013TR 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 L4973D3.3-013TR meets industry standards.

7.What is the process for return or replacement of L4973D3.3-013TR?

All L4973D3.3-013TR units undergo pre-shipment inspection (PSI). If there is an issue with L4973D3.3-013TR, 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 L4973D3.3-013TR part is unused and in its original packaging.

Return procedure for L4973D3.3-013TR:

1.Submit a request within 90 days.

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

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