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STMicroelectronics L4978D — Crystals & Oscillators

L4978D STMicroelectronics Step-Down Buck Regulator 2A

MPNL4978D
End of Life

STMicroelectronics L4978D, step-down buck regulator, 2A output, adjustable output, 55V max input, 100kHz–300kHz switching, -40°C to 150°C junction, 16-SOIC (0.295", 7.50mm width), tube packaging.

$4.12Ref. price · indicative, final on quote
STMicroelectronics L4978D datasheet (PDF)
Packaging16-SOIC (0.295", 7.50mm Width)
RoHSROHS3 Compliant
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

L4978D specifications
ParameterValue
Output typeAdjustable
MountingSurface Mount
Voltage - input55V
Voltage - output50V
Voltage - output (Min (Fixed))3.3V
Output current2A
Frequency100kHz ~ 300kHz
I/O channels1
Operating temperature-40°C ~ 150°C (TJ)
PackageTube
FunctionStep-Down
TopologyBuck
Case16-SOIC (0.295\", 7.50mm Width)
Output configurationPositive
Synchronous rectifierNo

Product details

What this buck regulator delivers

The L4978D is a 2A step-down buck regulator from STMicroelectronics, accepting an input from 8V up to 55V and delivering an adjustable output down to 3.3V. The 2A continuous output current sets the load budget for the downstream rail; the 55V input ceiling gives headroom for 48V telecom or 24V industrial buses with margin for transients. Switching frequency spans 100kHz to 300kHz, which directly affects inductor physical size and output ripple — lower frequencies ease EMI but need larger magnetics. The part does not include synchronous rectification, so the external Schottky diode must handle the full 2A peak current.

The wide range means derating the output current above 85°C ambient per the datasheet thermal curves; the 16-SO W package relies on the copper pour area on the PCB to keep the junction within limits.

For BOM quantities, we source per RFQ — confirm the required volume and we will quote against current market pricing.

Frequently asked questions

What is the output current of L4978D?

The L4978D delivers 2A continuous output current. This is the maximum DC load the regulator can supply; the actual limit at elevated ambient temperature depends on the PCB copper area and airflow.

What is the switching frequency of L4978D?

The switching frequency is adjustable between 100kHz and 300kHz. Lower frequencies reduce switching losses but require larger inductors; higher frequencies shrink magnetics but increase EMI filtering demands.