2A Step down switching regulator

The L4978 is a step down monolithic power switching regulator delivering 2A at a voltage between 3.3V and 50V (selected by a simple external divider). Realized in BCD mixed technology, the device uses an internal power D-MOS transistor (with a typical Rdson of 0.25Ω) to obtain very high efficency and high switching speed.

A switching frequency up to 300KHz is achievable (the maximum power dissipation of the packages must be observed). A wide input voltage range between 8V to 55V and output voltages regulated from 3.3V to 50V cover the majority of today’s applications. Features of this new generations of DC-DC converter include pulse-by-pulse current limit, hiccup mode for short circuit protection, voltage feedforward regulation, soft-start, protection against feedback loop disconnection, inhibit for zero current consumption and thermal shutdown.

The device is available in plastic dual in line, DIP-8 for standard assembly, and SO16W for SMD assembly.

Key Features

  • PROTECTION AGAINST FEEDBACK DISCONNECTION
  • INHIBIT FOR ZERO CURRENT CONSUMPTION
  • SOFT START FUNCTION
  • THERMAL SHUTDOWN
  • ZERO LOAD CURRENT OPERATION
  • VOLTAGE FEEDFORWARD
  • UP TO 2A STEP DOWN CONVERTER
  • PRECISE 3.3V (±1%) INTERNAL REFERENCE VOLTAGE
  • OPERATING INPUT VOLTAGE FROM 8V TO 55V
  • SWITCHING FREQUENCY ADJUSTABLE UP TO 300KHz
  • INTERNAL CURRENT LIMITING (PULSE-BYPULSE AND HICCUP MODE)
  • OUTPUT VOLTAGE ADJUSTABLE FROM 3.3V TO 50V

Circuit Diagram

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Resources

Technical Documentation

Product Specifications
Description Version Size
2A step down switching regulator 9.2 578 KB
Application Notes
Description Version Size
Designing with L4978, 2A high efficiency DC-DC convertery 9.2 793 KB
Design Notes & Tips
Description Version Size
ST1S03 alternative topology: Using a buck in a negative buck-boost configuration 1.1 359 KB

Publications and Collaterals

Brochures
Description Version Size
Brochure Power management guide 09.2017 3 MB
Support & Community


Sample & Buy

Part Number Package Packing Type Marketing Status Unit Price (US$) * Quantity ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors
L4978D013TR SO-16W Tape And Reel Active 1.389 1000 NEC EAR99 MALAYSIA MORE INFO DISTRIBUTOR AVAILABILITY
L4978 DIP-8 Tube Active 1.389 1000 NEC EAR99 MALAYSIA MORE INFO Get Sample Add to cart DISTRIBUTOR AVAILABILITY
L4978D SO-16W Tube Active 1.389 1000 NEC EAR99 MALAYSIA MORE INFO DISTRIBUTOR AVAILABILITY
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(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office  or our Distributors

Quality & Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
L4978D013TR ActiveSO-16WIndustrialEcopack1 0 0
L4978 ActiveDIP-8IndustrialEcopack2 (**) 0 0
L4978D ActiveSO-16WIndustrialEcopack1 0 0
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(**) The Material Declaration forms available on st.com may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.

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