Overview
The L4985A, produced by STMicroelectronics, is a peak current-mode Power Factor Correction (PFC) controller designed for boost converters. It features a proprietary multiplier "emulator" and innovative THD optimizers, ensuring very low Total Harmonic Distortion (THD) performance in all operating conditions. This device is particularly suited for Continuous Conduction Mode (CCM) operated boost PFC pre-regulators, complying with standards such as EN61000-3-2 and JEIDA-MITI, and is applicable in a power range from a few hundred watts to several kilowatts.
The L4985A includes an 800V high voltage start-up block with integrated input voltage sensing and active input filter capacitor discharge, which helps meet safety regulations without the need for traditional discharge resistors. It also features low consumption and disable functions, making it compliant with the latest energy-saving requirements from various regulatory bodies.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Supply Voltage (VCC) | -0.3 to 24.5 | V |
| Gate Driver Output Current | 0.7 A (source), 1.5 A (sink) | A |
| Switching Frequency | 65 kHz (L4985A), 130 kHz (L4985B) | kHz |
| Internal Reference Voltage | 1.2% (@ Tj = 25 °C) | % |
| Operating Temperature Range | -40 to 150 | °C |
| Package | SO-8 | |
| High Voltage Start-up | 800 V | V |
| Current Sense Input Range | -10 to 3.3 | V |
| Feedback Input Range | -0.3 to 3.0 | V |
Key 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
- Extremely few external components required
- Protections: feedback loop failure, overvoltage protection (OVP), overcurrent protection (OCP), inductor saturation, brown-in, brownout
- Inductor current sense and in-rush current monitoring
- Disable and low consumption function
- Soft-start for smooth startup
- Totem-pole output stage capable of driving big MOSFET or IGBT
Applications
- PFC pre-regulators for IEC61000-3-2 and JEIDA-MITI compliant SMPS in excess of 1 kW
- Desktop PC, server, web server, game console
- High power LED luminaries
- Industrial and medical SMPS according to IEC 60601-1-2
Q & A
- What is the primary function of the L4985A?
The L4985A is a peak current-mode Power Factor Correction (PFC) controller for boost converters.
- What are the key features of the L4985A's high voltage startup block?
The high voltage startup block includes an 800V high voltage startup with integrated input voltage sensing and active input filter capacitor discharge.
- What are the switching frequencies available for the L4985A and L4985B versions?
The L4985A operates at 65 kHz, while the L4985B operates at 130 kHz.
- What protections does the L4985A offer?
The L4985A offers protections against feedback loop failure, overvoltage protection (OVP), overcurrent protection (OCP), inductor saturation, brown-in, and brownout.
- How does the L4985A meet safety regulations?
The device meets safety regulations such as IEC 61010-1 or IEC 62368-1 without using traditional discharge resistors, thanks to its active input filter capacitor discharge function.
- What is the purpose of the soft-start feature in the L4985A?
The soft-start feature limits the peak current during startup, ensuring a smooth and controlled initialization of the system.
- What is the operating temperature range of the L4985A?
The operating temperature range is from -40°C to 150°C.
- What package type is the L4985A available in?
The L4985A is available in an SO-8 package.
- How does the L4985A comply with energy-saving requirements?
The device features low consumption and disable functions, making it compliant with the latest energy-saving requirements from various regulatory bodies such as Energy Star, the Department of Energy (DoE), and the European Code of Conduct.
- What are some typical applications of the L4985A?
Typical applications include PFC pre-regulators for high-power systems, desktop PCs, servers, web servers, game consoles, high power LED luminaries, and industrial and medical SMPS.
