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

STMicroelectronics E-L5973D

Name: E-L5973D
Brand: STMicroelectronics
SKU: E-L5973D
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: E-L5973D

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 8-SOIC (0.154", 3.90mm Width) Exposed Pad

Datasheet:: E-L5973D.pdf

Description:: IC REG BUCK ADJ 2.5A 8SO

Quantity:: RFQ Add To RFQ list

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Product details

Overview

L5973D from STMicroelectronics is a monolithic step-down switching regulator with an integrated 2.5 A P-channel D-MOS switch, 4–36 V input range, adjustable 1.235–35 V output, and fixed 250 kHz switching frequency. It delivers >2 A DC load current in typical applications, supports 100% duty cycle for low-dropout operation, and features internal voltage feedforward and zero-load current capability - used in LCD monitors, STB power supplies, and industrial DC-DC converters.

For engineers reviewing the L5973D datasheet, L5973D pinout, L5973D application, or L5973D equivalent, key selection criteria include its SO8 exposed-pad thermal performance (R_thJA = 40°C/W), ±2% reference accuracy, pulse-by-pulse current limiting, synchronization capability, and INH-controlled zero-quiescent-current shutdown mode.

Technical Context

The L5973D employs a voltage-mode control architecture with internal error amplifier, COMP pin for external compensation, and FB pin referenced to a precision 1.235 V bandgap. Its P-channel MOSFET switch (R_DS(on) = 250 mΩ typ.) enables high efficiency at light loads and eliminates the need for an external bootstrap capacitor.

Voltage feedforward improves line regulation by dynamically adjusting the PWM ramp slope in response to input voltage changes. The device integrates thermal shutdown, feedback disconnection protection, and INH-driven inhibit logic that pulls total standby current to ≤150 µA at 36 V input.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4 V to 36 V - supports direct connection to 5 V, 12 V, and 24 V rails without pre-regulation.
Output Voltage Range	1.235 V to 35 V - set via external resistor divider on FB pin; 1.235 V is internal reference voltage.
Switch Current Limit	2.5 A min - ensures ≥2 A continuous DC output under typical thermal conditions with HSOP8 exposed pad.
Switching Frequency	250 kHz fixed - balances EMI control, inductor size, and efficiency across wide input/output combinations.
Reference Voltage Accuracy	±2% over temperature - guarantees stable output regulation without trimming in consumer and industrial applications.
Thermal Resistance	R_thJA = 40°C/W - achieved via HSOP8 exposed pad; enables >2 A operation at +60°C ambient without forced airflow.
Quiescent Current	3 mA typ. operating / ≤150 µA standby - supports always-on systems and battery-backed modules.

Pinout & Package

Package: HSOP8 with exposed thermal pad (ECOPACK-compliant). Exposed pad must be soldered to PCB ground plane for optimal thermal performance and electrical stability.

Pin/Terminal	Circuit Role	Design Meaning
1 OUT	Power switch output node	Connects to inductor and output capacitor; carries pulsed high-current switching waveform.
2 SYNC	Synchronization input/output	Accepts external clock (slave) or outputs synchronized pulse (master); enables multi-phase or noise-shaped operation.
3 INH	Enable/disable control	Active-high logic input; open-circuit defaults to disable; grounded to enable; reduces I_Q to ≤150 µA when asserted.
4 COMP	Error amplifier output	Provides access to EA output for external compensation network (type II/III) to optimize transient response.
5 FB	Feedback input	Resistive divider connects here; regulates output to 1.235 V at this pin; open-loop gain >50 dB ensures tight regulation.
6 VREF	Internal 3.3 V reference output	Stable 3.3 V ±2% source; no external capacitor required; usable as bias supply for external circuitry.
7 GND	Analog and power ground	Common return for FB, COMP, INH, SYNC; must be connected to exposed pad and low-impedance ground plane.
8 VCC	Unregulated input supply	Primary power input (4–36 V); powers internal logic and gate driver; bypass capacitor required near pin.

Key Features

Feature	Design Value
Integrated P-channel MOSFET	R_DS(on) = 250 mΩ typ., eliminating external high-side switch and bootstrap components.
Voltage feedforward control	Improves line regulation to <10 mV over 4–36 V input range without additional compensation.
Zero-load operation	Maintains regulation with no minimum load; avoids need for dummy resistive load in standby mode.
INH-driven ultra-low standby	Reduces total quiescent current to ≤150 µA at 36 V input, enabling long-term battery backup.
Protection suite	Includes thermal shutdown, pulse-by-pulse current limit, feedback disconnect detection, and overvoltage clamp.

Applications

STB Power Supply

LCD Monitor DC-DC

Use Scenario: Primary 3.3 V/2 A rail generation from 12 V input in satellite set-top box mainboard.

IC Role / Device Role / Timing Role: Step-down regulator providing regulated main logic supply; operates at 250 kHz to avoid audible noise and align with system clock domains.

Use Value: Delivers >2 A continuously with R_thJA = 40°C/W, enabling compact heatsink-free design in space-constrained chassis.

Use Scenario: Adjustable 5 V/2.5 A backlight and logic rail in 24-inch LCD monitor power board.

IC Role / Device Role / Timing Role: Main buck controller managing dynamic load steps during brightness transitions; uses SYNC to phase-shift with secondary converter.

Use Value: Voltage feedforward ensures <15 mV line regulation across 12–24 V adapter input variation, preserving display stability.

Industrial DC-DC Converter

Car Radio Power Management

Use Scenario: 5 V/2 A isolated auxiliary supply in programmable logic controller (PLC) backplane module.

IC Role / Device Role / Timing Role: Non-isolated buck stage feeding downstream isolated DC-DC; INH pin controlled by PLC watchdog signal.

Use Value: INH-driven ≤150 µA standby current enables safe sleep mode during firmware updates without battery drain.

Use Scenario: 3.3 V/1.8 A infotainment processor core supply powered from vehicle 9–16 V battery rail.

IC Role / Device Role / Timing Role: Automotive-grade buck regulator handling cold-crank (4.4 V) and load-dump (36 V) transients per ISO 7637-2.

Use Value: 4–36 V input range and thermal shutdown protect against automotive voltage extremes while maintaining regulation.

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-ADJ	3 A switch, 150 kHz fixed frequency, no SYNC or VREF output, R_thJA ≈ 65°C/W in TO-263.	Lacks synchronization and precision reference; less suitable for noise-sensitive or multi-rail coordinated designs.	Prefer L5973D where thermal density, EMI control, or auxiliary 3.3 V bias is required.
MP1584EN-LF-Z	3 A switch, 1.5 MHz switching, no VREF output, no INH pin, R_thJA ≈ 50°C/W in SOIC-8.	Higher frequency enables smaller magnetics but increases switching loss above 12 V input; no zero-I_Q shutdown.	Prefer L5973D for 24 V input systems needing low standby power and robust thermal margin.

Compared with LM2596S-ADJ and MP1584EN-LF-Z, the L5973D uniquely combines 250 kHz EMI optimization, integrated 3.3 V reference, INH-controlled ultra-low standby, and 40°C/W thermal resistance - making it optimal for thermally constrained, multi-rail, or always-on industrial and consumer power systems.

Availability

L5973D is available at Aetrix Electronics and suitable for STB power supplies, LCD monitor DC-DC stages, and industrial PLC auxiliary converters requiring stable component supply, long-lifecycle support, and ECOPACK-compliant packaging.

Supply support for L5973D 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The L5973D belongs to ST's monolithic DC-DC converter product line, engineered specifically for high-current, wide-input-voltage industrial and consumer power supplies where thermal efficiency, protection robustness, and design simplicity are critical.

FAQ

What is the maximum continuous output current of the L5973D?

The L5973D guarantees a minimum switch current limit of 2.5 A and can deliver over 2 A DC to the load under typical conditions - confirmed by thermal testing at 60°C ambient with HSOP8 exposed pad soldered to 4-layer PCB ground plane. Actual output depends on input/output voltage, ambient temperature, and PCB copper area.

Does the L5973D require an external compensation network?

Yes - the COMP pin provides access to the error amplifier output and requires an external type II or type III compensation network (typically RC + C) connected between COMP, FB, and GND to ensure stability across all operating conditions. The datasheet provides design equations and example values for common configurations.

Can the L5973D operate with input voltage below 5 V?

Yes - the L5973D operates down to 4 V input, making it compatible with 5 V bus systems including USB-powered peripherals and low-voltage industrial controllers. At 4.4 V input, it maintains regulation with 100% duty cycle and delivers full rated current if thermal limits permit.

Is the VREF pin intended for external circuit biasing?

Yes - the VREF pin delivers a stable, buffered 3.3 V ±2% output capable of sourcing up to 5 mA. It is explicitly designed for biasing external circuitry such as ADC references, level shifters, or optocoupler LEDs, eliminating the need for a separate LDO in many designs.

E-L5973D Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width) Exposed Pad

Packaging:: Tube

Product Status:: Obsolete

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Adjustable

Number of Outputs:: 1

Voltage - Input (Min):: 4V

Voltage - Input (Max):: 36V

Voltage - Output (Min/Fixed):: 1.235V

Voltage - Output (Max):: 35V

Current - Output:: 2.5A

Frequency - Switching:: 250kHz

Synchronous Rectifier:: No

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SO

E-L5973D FAQ

1.How can I place an order for E-L5973D through Aetrix?

Please submit a Request for Quotation (RFQ) for E-L5973D 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-L5973D reliable?

The price and inventory of E-L5973D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for E-L5973D is usually 5 days.

3.What payment methods are accepted for E-L5973D?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for E-L5973D transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for E-L5973D?

E-L5973D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your E-L5973D 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-L5973D?

For technical support, including E-L5973D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your E-L5973D requirements.

6.How does Aetrix verify that E-L5973D is sourced from the original manufacturer or authorized distributors?

All E-L5973D 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-L5973D meets industry standards.

7.What is the process for return or replacement of E-L5973D?

All E-L5973D units undergo pre-shipment inspection (PSI). If there is an issue with E-L5973D, 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-L5973D part is unused and in its original packaging.

Return procedure for E-L5973D:

1.Submit a request within 90 days.

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

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