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L4985
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Education Design Win
Continuous conduction mode (CCM) PFC controller with high voltage startup

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Product overview

Description

The L4985 is a peak current-mode PFC controller for boost converter with a proprietary multiplier “emulator” which in addition to the innovative THD optimizers guarantee very low Total Harmonic Distortion (THD) performance in all operating conditions. The device comes in a pin SO package and offers a high performance/low-component count solution for CCM-operated boost PFC pre-regulators in EN61000-3-2 and JEIDA-MITI compliant applications, in a power range that spans from few hundred W to some kW.

The device, thanks to a proprietary off-time modulator, operates in quasi-fixed frequency in all operating conditions. Two options are available, 65 kHz for A and 130 kHz for B.

The 800V high voltage start-up block includes also the circuitry to discharge the X-capacitors of the EMI filter to a safe level. This allows the unit to meet safety regulation (such as IEC 61010-1 or IEC 62368-1) without using the traditional discharge resistor in parallel to the X-capacitors.

The device features low consumption and disable functions allowing usage in applications supposed to comply even with the latest energy saving requirements issued by Energy Star, the Department of Energy (DoE) in the United States, the European Code of Conduct, the European Union’s Ecodesign Directive, and other guidelines.

In addition to an overvoltage protection able to keep the output voltage under control during transient conditions, the IC is provided also with a protection against feedback loop failures or erroneous settings and boost inductor saturation. The brownout protection function allows to design medical equipment according to the latest regulations driven by IEC 60601-1-2 which requires the output regulation in case of mains dips lasting up to 500 msec. Soft-start limits the peak current.

The totem-pole output stage, capable of 0.7 A source and 1.5 A sink current, is suitable for big MOSFET or IGBT drives.

  • All features

    • Peak current mode CCM-operated
    • 800 V high voltage startup with integrated input voltage sensing
    • Active input filter capacitor discharge
    • Proprietary multiplier “emulator” with minimum THD of line current in all operating conditions (CCM and DCM)
    • Extremely few external components
    • Protections: feedback loop failure, OVP, OCP, inductor saturation, brown-in, brownout (compliant to medical SMPS standards)
    • Inductor current sense
    • Disable and low consumption function
    • In-rush current monitoring
    • Soft-start for smooth startup
    • 1.2% (@ Tj = 25 °C) internal reference voltage
    • 65 kHz (A version) and 130 kHz (B version) switching frequency
    • SO8 package
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SIMPLIS models (1)

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L4985A SIMPLIS Example Schematics
2025.08 28 Nov 2025
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28 Nov 2025
L4985A SIMPLIS Example Schematics 2025.08

Quality and Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Longevity Commitment Longevity Starting Date Material Declaration**
L4985A
Active
SO-8 Industrial Ecopack3 - -
L4985ATR
Active
SO-8 Industrial Ecopack3 - -
L4985B
Active
SO-8 Industrial Ecopack3 - -
L4985BTR
Active
SO-8 Industrial Ecopack3 - -

L4985A

Package:

SO-8

Material Declaration**:

PDF XML
More Info

Marketing Status

Active

Package

SO-8

Grade

Industrial

RoHS Compliance Grade

Ecopack3

L4985ATR

Package:

SO-8

Material Declaration**:

PDF XML
More Info

Marketing Status

Active

Package

SO-8

Grade

Industrial

RoHS Compliance Grade

Ecopack3

L4985B

Package:

SO-8

Material Declaration**:

PDF XML
More Info

Marketing Status

Active

Package

SO-8

Grade

Industrial

RoHS Compliance Grade

Ecopack3

L4985BTR

Package:

SO-8

Material Declaration**:

PDF XML
More Info

Marketing Status

Active

Package

SO-8

Grade

Industrial

RoHS Compliance Grade

Ecopack3

(**) 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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(*) Suggested Resale Price (USD) per defined quantity for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office or our Distributors

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