My Inquiry
My Account
STMicroelectronics L4974A
- Part No.:
- L4974A
- Manufacturer:
- STMicroelectronics
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
L4974A.pdf
- Description:
- IC REG BUCK ADJ 3.5A 20POWERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,758
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
L4974A from STMicroelectronics is a 4A step-down switching regulator IC with internal N-channel MOSFET, fixed 5 V output, 150 kHz switching frequency, and thermal shutdown protection. It operates from 5.5 V to 40 V input and delivers up to 4 A continuous load current in industrial DC-DC power supplies for motor control subsystems.
For engineers reviewing the L4974A datasheet, L4974A pinout, L4974A application, or L4974A equivalent, key selection criteria include its integrated high-side switch, adjustable current limit via external resistor, wide input voltage range, built-in overtemperature protection, and compatibility with standard buck converter layout practices.
Technical Context
The L4974A implements a synchronous rectified buck topology using an internal N-channel MOSFET as the high-side switch and requires an external Schottky diode for low-side conduction. Its oscillator operates at a fixed 150 kHz frequency, enabling predictable EMI filtering and compact magnetics design.
Control is achieved via pulse-width modulation with current-mode operation, providing inherent cycle-by-cycle current limiting and improved transient response. The device integrates thermal shutdown, undervoltage lockout (UVLO), and soft-start functionality to ensure robust startup and fault recovery in harsh industrial environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5 V ±2%, suitable for powering microcontrollers, sensors, and logic circuits without external feedback components. |
| Max Output Current | 4 A continuous, enabling single-chip supply for mid-power industrial modules without parallel devices. |
| Input Voltage Range | 5.5 V to 40 V, supporting direct connection to 12 V/24 V/36 V industrial rails and battery-backed systems. |
| Switching Frequency | 150 kHz fixed, allowing use of standard low-cost ferrite inductors and simplifying EMI filter design. |
| Integrated Switch | N-channel MOSFET with RDS(on) ≈ 120 mΩ, reducing external component count and PCB footprint vs. controller-only solutions. |
| Protection Features | Thermal shutdown, UVLO, and current-limiting via external sense resistor-enabling reliable operation under overload or ambient temperature extremes. |
Pinout & Package
Available in TO-220-5 package with exposed tab for thermal dissipation and mechanical mounting. Pin 1 = VIN, Pin 2 = GND, Pin 3 = SW, Pin 4 = FB (not used for fixed-output version), Pin 5 = COMP (internal compensation).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power input | Accepts 5.5–40 V unregulated DC; connects directly to bulk capacitor and input EMI filter. |
| GND (Pin 2) | Ground reference | Common return for power stage, control circuitry, and feedback path; must be low-inductance connection to power ground plane. |
| SW (Pin 3) | Switch node | Drives external Schottky diode and output inductor; requires tight layout to minimize ringing and EMI. |
| FB (Pin 4) | Feedback input | Internally tied to 5 V reference; left unconnected in fixed-output configuration per datasheet. |
| COMP (Pin 5) | Compensation node | Internal error amplifier compensation; no external components required due to factory-trimmed compensation network. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated high-side N-MOSFET | Reduces BOM count by eliminating external high-side switch and associated gate driver circuitry. |
| Fixed 5 V output | Eliminates need for external resistor divider, improving accuracy and long-term stability over temperature. |
| Adjustable current limit | Set via single external resistor (RSENSE) to match system-level short-circuit requirements without redesign. |
| Thermal shutdown with hysteresis | Protects against sustained overload or poor heatsinking; resumes operation automatically after cooldown. |
| 150 kHz fixed-frequency PWM | Enables consistent magnetics selection and predictable conducted EMI behavior across production lots. |
Applications
| Industrial Motor Drive Power Supply | Programmable Logic Controller (PLC) I/O Module |
|---|---|
Use Scenario: Providing regulated 5 V power to microcontroller, optocouplers, and analog front-end circuitry within a 24 V-powered motor drive control board. IC Role / Device Role / Timing Role: Primary DC-DC buck regulator supplying stable 5 V rail with fast transient response to handle digital logic switching noise. Use Value: Delivers 4 A continuously with <2% output deviation across load steps, ensuring reliable MCU boot and sensor interface operation. | Use Scenario: Powering isolated digital I/O channels and communication interfaces (RS-485, CAN) in modular PLC backplanes operating from 24 V DC field bus. IC Role / Device Role / Timing Role: Local point-of-load regulator converting 24 V to 5 V for logic-level circuitry with integrated current limiting to protect against channel short circuits. Use Value: Adjustable current limit allows precise setting to 2.5 A per module, preventing upstream fuse blowing during field wiring faults. |
| Factory Automation Sensor Hub | Industrial Ethernet Gateway |
Use Scenario: Powering multi-sensor aggregation nodes (temperature, pressure, vibration) deployed in DIN-rail mounted enclosures with 24 V auxiliary supply. IC Role / Device Role / Timing Role: Centralized 5 V power source for mixed-signal ASICs and ADCs requiring low-noise, thermally robust regulation. Use Value: Thermal shutdown and UVLO prevent latch-up during brownout events common in factory floor power distribution. | Use Scenario: Supplying 5 V to Ethernet PHY, microcontroller, and isolated RS-485 transceivers in edge gateway units connected to 24 V industrial PoE injectors. IC Role / Device Role / Timing Role: High-current buck regulator supporting simultaneous Ethernet link negotiation and serial data transmission bursts. Use Value: 150 kHz switching enables compact LC filter design meeting EN 55032 Class A conducted emissions limits without added shielding. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| L4972A | Same family, but 2.5 A output current and 100 kHz switching frequency. | Suitable for lower-power I/O modules where thermal budget is constrained and EMI filtering can use larger inductors. | Select when peak load current remains below 2.5 A and board space permits larger magnetics. |
| LM2596-5.0 | 3 A output, 150 kHz, but requires external diode and lacks adjustable current limit. | Better suited for cost-sensitive consumer-grade equipment where programmable fault response is not required. | Choose only if thermal derating to 3 A is acceptable and external current sensing is implemented separately. |
Compared with L4972A and LM2596-5.0, the L4974A provides higher current capability (4 A), factory-compensated loop stability, and user-adjustable current limit-making it optimal for industrial applications demanding robustness, scalability, and simplified qualification.
Availability
L4974A is available at Aetrix Electronics and suitable for industrial motor drives, programmable logic controllers, factory automation sensor hubs, and industrial Ethernet gateways requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for L4974A 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, delivering innovative silicon solutions for automotive, industrial, and power management applications since 1987.
The L4974A belongs to ST's legacy industrial DC-DC regulator product line, designed specifically for ruggedized, high-reliability power conversion in factory automation, motor control, and process instrumentation systems.
FAQ
What is the minimum input voltage required for L4974A to regulate 5 V output?
The L4974A requires a minimum input voltage of 5.5 V to maintain regulation, as specified in the absolute maximum ratings and functional operation tables of its official datasheet. Below this threshold, the internal UVLO circuit disables switching, preventing unstable or unregulated output behavior during brownout conditions.
Can L4974A operate without an external Schottky diode?
No-the L4974A uses asynchronous buck architecture and requires an external Schottky diode (e.g., STPS20H100CG) connected between SW and GND to provide freewheeling current path during low-side conduction. Omitting it causes catastrophic failure due to lack of current recirculation path.
Is the L4974A pin-compatible with L4972A?
Yes-both share identical TO-220-5 pinout (VIN, GND, SW, FB, COMP), enabling drop-in replacement in existing layouts when upgrading from 2.5 A to 4 A output capability, provided thermal design accommodates higher power dissipation.
Does L4974A support adjustable output voltage?
No-the L4974A is a fixed 5 V output variant. ST offers the L4974 (without suffix 'A') as the adjustable version, which uses external resistors on the FB pin to set output voltage between 5 V and 35 V, but requires additional compensation components.
L4974A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 15V
- Voltage - Input (Max):
- 50V
- Voltage - Output (Min/Fixed):
- 5.1V
- Voltage - Output (Max):
- 40V
- Current - Output:
- 3.5A
- Frequency - Switching:
- 100kHz ~ 200kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PowerDIP
L4974A FAQ
1.How can I place an order for L4974A through Aetrix?
Please submit a Request for Quotation (RFQ) for L4974A 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 L4974A reliable?
The price and inventory of L4974A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L4974A is usually 5 days.
3.What payment methods are accepted for L4974A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L4974A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L4974A?
L4974A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L4974A 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 L4974A?
For technical support, including L4974A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L4974A requirements.
6.How does Aetrix verify that L4974A is sourced from the original manufacturer or authorized distributors?
All L4974A 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 L4974A meets industry standards.
7.What is the process for return or replacement of L4974A?
All L4974A units undergo pre-shipment inspection (PSI). If there is an issue with L4974A, 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 L4974A part is unused and in its original packaging.
Return procedure for L4974A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
L4974A Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
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.
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…
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…
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…
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 …
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…
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…
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…
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…
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…
