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STMicroelectronics E-L4978D
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- Part No.:
- E-L4978D
- Manufacturer:
- STMicroelectronics
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
E-L4978D.pdf
- Description:
- IC REG BUCK ADJ 2A 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,857
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Product details
Overview
E-L4978D from STMicroelectronics is a monolithic step-down switching regulator IC delivering up to 2A continuous output current, operating from 8V to 55V input, with adjustable output voltage from 3.3V to 50V and internal 3.3V ±1% reference. It integrates a 0.25Ω D-MOS power transistor, supports up to 300kHz switching frequency, and features pulse-by-pulse current limiting, thermal shutdown, and soft-start-used in industrial power supplies and telecom DC-DC conversion stages.
For engineers reviewing the E-L4978D datasheet, E-L4978D pinout, E-L4978D application, or E-L4978D equivalent, key selection criteria include input voltage range (8–55V), output adjustability (3.3–50V), SO16W package thermal resistance (110°C/W), and integrated protection features including feedback disconnection detection and hiccup-mode short-circuit response.
Technical Context
The L4978 employs voltage feedforward control to improve line regulation and transient response across wide input variations. Its error amplifier provides 57dB open-loop gain and 2.5mS transconductance, enabling stable compensation with external RC networks on the COMP pin.
Switching frequency is set externally via ROSC and COSC, supporting 90–110kHz typical operation (up to 300kHz), while internal bootstrap circuitry drives the high-side MOSFET gate. The device operates in continuous conduction mode (CCM) at full load and transitions to zero-load quiescent mode (<200µA standby current) when INHIBIT is asserted.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 2A continuous; enables single-chip 3.3V/2A or 24V/2A point-of-load conversion without external pass devices. |
| Input Voltage Range | 8V to 55V; supports 12V/24V/48V industrial bus rails and automotive battery-supplied systems with wide transients. |
| Output Voltage Range | 3.3V to 50V adjustable via external resistor divider; 3.3V fixed when FB tied directly to output. |
| Switching Frequency | Up to 300kHz; allows compact magnetics and filtering while maintaining >87% efficiency at 3.3V/2A. |
| Reference Voltage | 3.3V ±1% at 25°C; ensures tight output regulation over temperature and line/load conditions. |
| Thermal Shutdown | Activates at Tj ≈ 150°C; protects against sustained overload or poor heatsinking in enclosed environments. |
| Quiescent Current | 6mA operating / 200µA standby; enables low-power sleep modes in battery-backed or energy-conscious systems. |
Pinout & Package
E-L4978D is supplied in SO16W (wide-body SOIC-16) surface-mount package with 1.27mm pitch, 10.1–10.5mm body width, and 110°C/W junction-to-ambient thermal resistance when mounted on standard PCB.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 7, 8, 9, 10, 15, 16 | No Connect (NC) | Not internally bonded; must be left floating or grounded per layout guidelines-no electrical function. |
| 2 | GND | Power and signal ground reference; requires low-impedance connection to minimize noise coupling into error amplifier. |
| 3 | SS_INH | Active-low inhibit/soft-start control; capacitor to GND sets soft-start time; grounding disables regulator with <200µA supply current. |
| 4 | OSC | Oscillator timing node; external R+C sets switching frequency and enables automatic line feedforward compensation. |
| 5 | OUT | Power switch output node; connects to external inductor and freewheeling diode; carries high di/dt pulsed current. |
| 6 | VCC | Unregulated input supply; powers internal circuitry; must be decoupled with ≥100nF ceramic near pin. |
| 11 | BOOT | Bootstrap capacitor terminal; forms charge pump for high-side gate drive; requires 100nF–220nF ceramic between BOOT and OUT. |
| 12 | COMP | Error amplifier output; connects to external RC compensation network to stabilize loop dynamics and phase margin. |
| 13 | FB | Feedback input; senses output voltage via resistive divider; open-circuit triggers protection and forces shutdown. |
| 14 | VCC | Duplicate VCC pin (same net as pin 6); improves current sharing and reduces trace inductance in high-current layouts. |
Key Features
| Feature | Design Value |
|---|---|
| Voltage Feedforward Regulation | Improves line transient response by scaling oscillator ramp with input voltage-reduces output deviation during 8→55V steps. |
| Pulse-by-Pulse Current Limiting | Monitors peak switch current each cycle; limits to ~3A typ., preventing magnetic saturation and MOSFET failure under overload. |
| Hiccup-Mode Short-Circuit Protection | After fault detection, device shuts down for ~10ms, then retries-limits average power dissipation during sustained shorts. |
| Soft-Start Function | Controlled output voltage ramp via SS_INH capacitor; prevents inrush current into bulk capacitors and avoids system brownouts. |
| Feedback Disconnection Protection | Internal comparator detects open FB node and forces shutdown-avoids uncontrolled high-voltage runaway in divider failure. |
Applications
| Industrial PLC Power Supply | Telecom Line Card DC-DC |
|---|---|
|
Use Scenario: Providing isolated 3.3V/2A bias rail for FPGA, microcontroller, and interface ICs inside programmable logic controller backplanes. IC Role / Device Role / Timing Role: Primary non-isolated buck regulator converting 24V or 48V backplane voltage to clean 3.3V logic supply. Use Value: Integrated 0.25Ω MOSFET eliminates external switch, reducing BOM count and board area while sustaining >87% efficiency at full load. |
Use Scenario: Generating 5.1V/2A intermediate rail from -48V telecom battery feed (via intermediate boost stage) for digital signal processors and SerDes PHYs. IC Role / Device Role / Timing Role: High-input-voltage buck controller accepting up to 55V input after front-end conversion, delivering tightly regulated mid-rail. Use Value: 8–55V input range accommodates upstream converter ripple and transients; ±1% reference ensures compliance with DSP core voltage tolerance. |
| Automotive Body Control Module | Test Equipment Auxiliary Supply |
|
Use Scenario: Converting 12V vehicle battery (with cold-crank dips to 6V and load-dump spikes to 60V) to stable 12V or 15V auxiliary rail for sensors and CAN transceivers. IC Role / Device Role / Timing Role: Input-tolerant buck regulator with thermal shutdown and hiccup protection-operates through automotive transients without latch-off. Use Value: Absolute max input rating of 58V and thermal shutdown at 150°C enable robust operation in under-hood environments without external clamping. |
Use Scenario: Building benchtop programmable DC source modules requiring adjustable 3.3–50V output at ≤2A, with remote ON/OFF and soft-start for calibration stability. IC Role / Device Role / Timing Role: Core regulating element in modular lab supply design, controlled via DAC-driven FB divider and microcontroller-driven SS_INH. Use Value: Adjustable frequency (up to 300kHz) allows optimization for low-noise (low-f) or compact size (high-f); inhibit pin enables precise sequencing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5116PWPR | Wide-input (6–100V), external MOSFET driver; no integrated power FET; higher max frequency (1MHz). | Requires external high-side/low-side MOSFETs and gate drivers; suited for >5A designs where thermal management dominates. | Select when output current exceeds 2A or when custom MOSFET selection (e.g., SiC/GaN) is required for efficiency or frequency targets. |
| TPS54202DRCT | Lower input range (4.5–28V), integrated 28mΩ FETs, fixed 500kHz frequency, smaller 10-pin WSON package. | Not rated for >28V input; unsuitable for 48V telecom or industrial bus rails; optimized for cost-sensitive consumer power. | Choose only for sub-28V applications where footprint and BOM cost outweigh need for wide VIN and rugged protection. |
Compared with LM5116PWPR and TPS54202DRCT, E-L4978D uniquely balances integrated 2A capability, 55V input rating, and comprehensive protection-including hiccup mode, feedback disconnect detection, and zero-load current-making it optimal for industrial and telecom 2A buck stages where reliability trumps raw density or ultra-high frequency.
Availability
E-L4978D is available at Aetrix Electronics and suitable for industrial PLC power supplies, telecom line card DC-DC conversion, and automotive body control modules requiring stable component supply across extended temperature and voltage ranges.
Supply support for E-L4978D 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, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and communications markets.
The L4978 belongs to ST's legacy high-voltage monolithic DC-DC regulator family, engineered for ruggedness in harsh environments-emphasizing wide input range, integrated protection, and thermal resilience over minimal footprint.
FAQ
What is the maximum allowable input voltage for E-L4978D?
The absolute maximum input voltage at the VCC pin is 58V, with recommended operating range from 8V to 55V. Exceeding 58V risks permanent damage to the internal D-MOS transistor and control circuitry. Transient spikes beyond 55V must be clamped externally using TVS diodes rated for ≤58V standoff voltage.
Can E-L4978D operate with no output load?
Yes-E-L4978D supports zero-load current operation with total quiescent current of 200µA in inhibited (standby) mode and 6mA in active regulation. In light-load CCM, it maintains regulation without skipping cycles, unlike some hysteretic controllers that induce audible noise or output ripple.
How is the switching frequency set, and what is its stability?
Frequency is set by an external resistor from VCC to OSC and a capacitor from OSC to GND. With Rosc = 20kΩ and Cosc = 2.7nF, typical fsw is 100kHz, varying ±6% over 8–55V input and ±4% across –40°C to +125°C junction temperature-enabled by voltage feedforward architecture.
What happens if the FB pin becomes disconnected?
E-L4978D includes dedicated feedback disconnection protection: if FB floats above 3.8V or drops below 2.5V, the error amplifier saturates and internal logic forces shutdown within microseconds. This prevents uncontrolled high-voltage output and is independent of external resistor divider values.
E-L4978D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 55V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- 50V
- Current - Output:
- 2A
- Frequency - Switching:
- 100kHz ~ 300kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
E-L4978D FAQ
1.How can I place an order for E-L4978D through Aetrix?
Please submit a Request for Quotation (RFQ) for E-L4978D 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-L4978D reliable?
The price and inventory of E-L4978D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for E-L4978D is usually 5 days.
3.What payment methods are accepted for E-L4978D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for E-L4978D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for E-L4978D?
E-L4978D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your E-L4978D 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-L4978D?
For technical support, including E-L4978D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your E-L4978D requirements.
6.How does Aetrix verify that E-L4978D is sourced from the original manufacturer or authorized distributors?
All E-L4978D 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-L4978D meets industry standards.
7.What is the process for return or replacement of E-L4978D?
All E-L4978D units undergo pre-shipment inspection (PSI). If there is an issue with E-L4978D, 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-L4978D part is unused and in its original packaging.
Return procedure for E-L4978D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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