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

STMicroelectronics E-L4973V3.3

Name: E-L4973V3.3
Brand: STMicroelectronics
SKU: E-L4973V3.3
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: E-L4973V3.3

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 18-DIP (0.300", 7.62mm)

Datasheet:: E-L4973V3.3.pdf

Description:: IC REG BUCK ADJ/0.5V 3.5A 18DIP

Quantity:: RFQ Add To RFQ list

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Inventory:2,809

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Product details

Overview

E-L4973V3.3 from STMicroelectronics is a monolithic step-down switching regulator delivering 3.5 A at a fixed 3.3 V ±1% output, operating from 8 V to 55 V input, featuring internal D-MOS (R_DS(on) = 0.15 Ω typ.), adjustable switching frequency up to 300 kHz, and zero-load quiescent current of 1 mA - deployed in industrial power supplies and automotive body control modules.

For engineers reviewing the E-L4973V3.3 datasheet, E-L4973V3.3 pinout, E-L4973V3.3 application, or E-L4973V3.3 equivalent, key selection criteria include input voltage range (8–55 V), fixed 3.3 V output tolerance (±1%), thermal shutdown behavior, soft-start timing control, and SO-20 (12+4+4) package compatibility with high-current PCB layouts.

Technical Context

The L4973V3.3 integrates a BCD-process D-MOS power switch and error amplifier with voltage feed-forward regulation, enabling stable output under wide input transients. Its oscillator supports external R/C programming (90–300 kHz), and synchronization capability allows master/slave multi-regulator coordination without phase conflict.

Internal protections include pulse-by-pulse current limiting, hiccup-mode short-circuit recovery, feedback disconnection detection, and thermal shutdown at 150 °C. The device operates down to zero load current (2.7 mA typ. quiescent, 100 µA in inhibit mode at V_CC = 24 V), supporting always-on systems.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.3 V ±1% - ensures stable logic supply for 3.3 V microcontrollers and FPGAs without external feedback divider.
Max Output Current	3.5 A continuous - supports high-current loads like motor drivers or multi-rail PMIC front-ends.
Input Voltage Range	8 V to 55 V - accommodates 12 V/24 V/48 V industrial and automotive battery systems with surge margin.
R_DS(on)	0.15 Ω typical - minimizes conduction loss and enables >85% efficiency at 3.3 V/3.5 A (V_CC = 24 V).
Switching Frequency	Adjustable 90–300 kHz - balances EMI control, inductor size, and MOSFET switching loss for compact designs.
Quiescent Current	2.7 mA (no load), 100 µA (inhibit active) - extends battery life in standby modes of telematics and sensor nodes.
Thermal Shutdown	150 °C junction - protects against sustained overload or poor heatsinking in enclosed enclosures.

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), rated for 4 W max power dissipation at T_pins = 90 °C.

Pin/Terminal	Circuit Role	Design Meaning
2,3 OUT	Power output node	High-current path to inductor and output capacitor; requires low-inductance layout to minimize ringing.
4–7,14–17 GND	Signal and power ground	Eight dedicated ground pins reduce impedance and improve noise immunity for feedback and current sensing.
8,9 VCC	Unregulated input supply	Accepts 8–55 V; powers internal circuitry and bootstrap driver; requires local 10 µF ceramic decoupling.
10 INH	Inhibit control input	Active-high logic input; pulls device into <100 µA standby when driven ≥3.0 V; must tie to GND if unused.
11 COMP	Error amplifier output	Connects to RC compensation network for loop stability; sets phase margin and transient response.
12 VFB	Feedback input	Direct connection yields 3.3 V output; external resistor divider required for adjustable outputs ≥0.5 V.
13 V5.1	5.1 V reference output	Stable 5.1 V ±1.5% reference available for auxiliary circuits or precision ADC references.
18 SYNC	Synchronization I/O	Configurable as input (slave) or open-drain output (master); enables deterministic interleaving of multiple regulators.
19 SS	Soft-start timing node	Capacitor-connected pin controls startup ramp rate; prevents inrush current and output overshoot.
20 BOOT	Bootstrap gate drive	Connects external capacitor between BOOT and OUT to generate gate voltage >V_OUT for high-side D-MOS drive.

Key Features

Feature	Design Value
Voltage feed-forward regulation	Compensates for input line variations in real time, reducing output deviation during 8–55 V transients without increasing loop gain.
Pulse-by-pulse current limiting	Monitors peak switch current each cycle and terminates conduction immediately - prevents MOSFET destruction during short-circuit events.
Hiccup-mode protection	After current-limit activation, device shuts down for ~10 ms, then retries - limits average power during sustained overloads.
Zero-load operation	Maintains regulation with only 1 mA output current, enabling use in low-power sleep states without disabling regulation.
External soft-start control	RC-timed ramp on SS pin ensures monotonic output rise, eliminating startup oscillation and inrush stress on input capacitors.

Applications

Industrial PLC Power Supply

Automotive Body Control Module

Use Scenario: Converts 24 V vehicle battery to stable 3.3 V for MCU, CAN transceivers, and sensors in door modules.

IC Role / Device Role / Timing Role: Primary buck regulator providing isolated, low-noise 3.3 V rail with hiccup-mode fault recovery during load dump events.

Use Value: Maintains operation across cold-crank (6.5 V) to load-dump (55 V) conditions while consuming only 100 µA in sleep mode.

Use Scenario: Powers 3.3 V FPGA configuration and I/O banks in programmable logic controllers with 48 V DC input.

IC Role / Device Role / Timing Role: High-efficiency, thermally robust step-down converter delivering 3.5 A with integrated thermal shutdown.

Use Value: Eliminates need for external current sense or thermal monitoring due to built-in pulse-by-pulse limiting and 150 °C shutdown.

Telecom Remote Radio Unit

Medical Portable Diagnostic Device

Use Scenario: Generates 3.3 V from 48 V PoE-derived supply in outdoor small-cell base stations with ambient temperatures up to 85 °C.

IC Role / Device Role / Timing Role: Main DC-DC converter with sync capability to align switching with other rails and reduce conducted EMI.

Use Value: Adjustable frequency (up to 300 kHz) enables optimal trade-off between filter size and thermal performance in sealed enclosures.

Use Scenario: Supplies 3.3 V to low-power ARM Cortex-M microcontroller and analog front-end in battery-operated ultrasound probes.

IC Role / Device Role / Timing Role: Always-on regulator maintaining regulation during deep-sleep cycles with <1 mA no-load current.

Use Value: Inhibit pin reduces system standby current to 100 µA, extending lithium-ion battery runtime by >20% versus non-inhibit alternatives.

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	3 A max output, fixed 3.3 V, 150 kHz fixed frequency, no sync or hiccup mode, R_DS(on) ≈ 0.22 Ω.	Lacks input synchronization, thermal foldback, and zero-load operation - unsuitable for multi-rail coordinated systems or ultra-low-power standby.	Select only for cost-sensitive, low-current (<3 A), non-safety-critical applications where thermal headroom is ample.
MP2451DT-LF-Z	2 A max output, 3.3 V fixed, 2 MHz switching, smaller SO-8 package, no internal MOSFET gate driver boot circuit.	Higher frequency enables tiny inductors but increases switching loss at 3.5 A; lacks V5.1 reference and inhibit function.	Prefer for space-constrained, medium-current designs where 2 MHz operation justifies lower current rating and missing features.

Compared with LM2596S-3.3 and MP2451DT-LF-Z, E-L4973V3.3 uniquely combines 3.5 A capability, 8–55 V input range, hiccup-mode protection, and 100 µA inhibit current - making it the only choice for ruggedized 24/48 V systems requiring full-feature fault resilience and zero-load regulation.

Availability

E-L4973V3.3 is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control modules, telecom remote radio units, and medical portable diagnostic devices requiring stable component supply across extended temperature and voltage ranges.

Supply support for E-L4973V3.3 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 silicon solutions for automotive, industrial, and power management applications.

The L4973 series belongs to ST's high-voltage monolithic DC-DC converter product line, engineered specifically for robust 8–55 V step-down conversion in harsh environments where reliability, thermal resilience, and integrated protection are critical.

FAQ

What is the minimum input voltage required for E-L4973V3.3 to regulate 3.3 V output?

The absolute minimum input voltage is 8 V, verified per datasheet Table 4. Below this, regulation fails due to insufficient headroom for the internal D-MOS dropout and control circuitry. At V_IN = 8 V, the device sustains 3.5 A output with ≤100 mV line regulation error and maintains soft-start functionality.

Can E-L4973V3.3 be used with an external MOSFET instead of its internal switch?

No - the L4973V3.3 integrates a single internal D-MOS transistor and lacks gate-drive outputs for external high-side or synchronous rectifier MOSFETs. Its BOOT pin drives only the internal switch; no provision exists for external FET control or synchronous rectification.

How does the SYNC pin function in master vs. slave configuration?

In master mode, SYNC outputs a 5 V open-drain signal synchronized to the internal oscillator; in slave mode, it accepts an external clock (3.5–5.5 V high, ≤0.9 V low) to lock switching frequency and phase. Both modes require 0.15–0.45 mA sink current per datasheet Table 4.

Is the 3.3 V output trimmed or factory-laser-trimmed for accuracy?

Yes - the 3.3 V output is factory-trimmed to ±1% tolerance at I_O = 1 A, TJ = 25 °C, as specified in Table 4. Over temperature (−40 to 125 °C) and load (0.5–3.5 A), total variation remains within ±2.5%, confirmed by Figures 13–16 in the datasheet.

E-L4973V3.3 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 18-DIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Obsolete

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:: Through Hole

Supplier Device Package:: 18-DIP

E-L4973V3.3 FAQ

1.How can I place an order for E-L4973V3.3 through Aetrix?

Please submit a Request for Quotation (RFQ) for E-L4973V3.3 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 E-L4973V3.3 reliable?

The price and inventory of E-L4973V3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for E-L4973V3.3 is usually 5 days.

3.What payment methods are accepted for E-L4973V3.3?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for E-L4973V3.3 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for E-L4973V3.3?

E-L4973V3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your E-L4973V3.3 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 E-L4973V3.3?

For technical support, including E-L4973V3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your E-L4973V3.3 requirements.

6.How does Aetrix verify that E-L4973V3.3 is sourced from the original manufacturer or authorized distributors?

All E-L4973V3.3 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 E-L4973V3.3 meets industry standards.

7.What is the process for return or replacement of E-L4973V3.3?

All E-L4973V3.3 units undergo pre-shipment inspection (PSI). If there is an issue with E-L4973V3.3, 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 E-L4973V3.3 part is unused and in its original packaging.

Return procedure for E-L4973V3.3:

1.Submit a request within 90 days.

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

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