Blog Perusahaan Tentang Supply Renesas AC/DC Converters:Flyback & Forward Controller,Non‑Isolated AC/DC Buck Converter

Supply Renesas AC/DC Converters:Flyback & Forward Controller,Non‑Isolated AC/DC Buck Converter

Shenzhen Mingjiada Electronics Co., Ltd. is a specialist supplier with nearly 30 years’ experience in the electronic components industry. With our professional sales team and stable supply channels, we provide our customers with comprehensive electronic component supply services.

Core Competitive Advantages:

Extensive inventory system: The company operates warehouses in Hong Kong, Shenzhen and other locations, with over 2 million SKUs in stock.

Strict quality control: All materials undergo rigorous quality inspections prior to warehousing to ensure compliance with original manufacturers’ technical standards and to guarantee the supply of genuine products.

Diversified product portfolio: Covering electronic components for multiple sectors including 5G, new energy, the Internet of Things (IoT), connected vehicles, base station communications, artificial intelligence and radio frequency (RF).

[Isolated AC/DC – Flyback Controllers]

1. Topology Classification

The flyback topology is the most widely used solution for small- to medium-power isolated power supplies (5W–120W). It features a simple structure, with the transformer serving both energy storage and electrical isolation functions, making it suitable for chargers, adapters, LED drivers and isolated auxiliary power supplies. Renesas’ flyback controllers are categorised into four main product lines: primary-side PSR solutions (without optocouplers), secondary-side feedback solutions (with optocouplers), integrated MOSFET-based solutions, and external MOSFET controller solutions. They support PWM, quasi-resonant (QR) valley switching, and burst mode.

2. Core Technical Advantages

Quasi-resonant (QR) valley switching technology: Conducts at the valley under heavy loads to reduce switching losses and EMI, whilst improving overall system efficiency; automatically switches to Burst mode under light loads to achieve ultra-low no-load power consumption, meeting global energy efficiency regulations (CEC, ERP).

PrimAccurate™ Primary-Side Regulation (PSR): Eliminates the need for optocouplers and TL431 secondary-side feedback by utilising sampling from the transformer’s auxiliary winding, significantly reducing the number of external components and minimising PCB footprint. Built-in cable voltage drop compensation improves fast-charging output accuracy.

Frequency Dithering: Broadens the EMI spectrum, reduces the requirements for filtering components, and simplifies conducted and radiated EMI design.

Comprehensive protection system: Cycle-by-cycle current limiting, output short-circuit protection (SCP), overload protection (OLP), VCC overvoltage/undervoltage lockout (UVLO), on-chip over-temperature protection (OTP), and open-loop feedback protection.

3. Representative Devices and Solution Features

iW1691 Quasi-Resonant PSR Flyback Controller (External MOSFET)

Digitally controlled peak current mode; no optocoupler required for primary-side regulation; switching frequency up to 130 kHz, suitable for 10–30 W adapters and compact chargers; no loop compensation required, with excellent transient load response.

iW1780 / iW1782 Fast Charging QR Flyback Controller

Supports QC/USB PD fast charging applications with secondary-side digital communication; adaptive load frequency control, compatible with synchronous rectification; no-load power consumption <10 mW, designed for 20–65 W fast-charging power supplies for mobile phones and laptops.

RAA223882 Integrated 700V MOS Flyback Switch

Current-mode fixed-frequency PWM, light-load burst mode; built-in high-voltage start-up and frequency jitter; single-chip integrated power switch, suitable for household appliances and industrial isolated bias power supplies up to 15W.

RAA223181 Integrated 900V MOS High-Voltage Flyback Regulator

Suitable for wide voltage ranges and overvoltage conditions, designed for power line communication (PLC) power supplies in smart meters; limits burst frequency to avoid PLC interference, provides short-term peak power output, and reduces component margin costs across the entire system.

4. Typical Applications

USB chargers, power adaptors, isolated industrial auxiliary power supplies, LED driver power supplies, isolated power supplies for inverter-based household appliances, and isolated power supplies for smart meters.

[Isolated AC/DC – Forward Converter]

1. Topology Overview

The forward topology is suitable for medium to high-power continuous output (60W–400W). As the transformer does not store energy and energy is transferred directly, output ripple is lower, making it suitable for continuous high-current loads. Compared to the flyback topology, it places less stress on magnetic components at the same power density and is commonly used in industrial power supplies, server standby power supplies, high-power telecommunications power supplies and medical power supplies.

Differences from flyback: Forward converters must be paired with a reset winding or a magnetic reset circuit, and the output side requires a freewheeling diode or synchronous rectifier.

2. Key Features of Renesas Forward Converters

Renesas forward converters primarily utilise an external MOSFET current-mode PWM architecture, supporting single-ended forward and active-clamped forward topologies. They are specifically designed for industrial applications with stringent requirements for output ripple and long-term continuous reliability.

Precise peak current-mode control: High loop stability, simplified loop compensation, and excellent linearity and load regulation.

Programmable maximum duty cycle limit: Protects the transformer core from saturation and accommodates various magnetic reset schemes (reset winding, RCD, active clamping).

Configurable soft start: Suppresses inrush current during power-up, reducing stress on input capacitors and power devices.

Multi-mode protection: Cycle-by-cycle current limiting, output short-circuit hiccup protection, input under-voltage lockout, over-temperature shutdown, and output over-voltage protection.

Synchronisable switching frequency: Supports synchronisation in multi-power-supply systems, mitigates beat frequency interference, and simplifies system EMI management.

Application Guidance

The forward converter configuration offers a higher power limit and superior continuous load characteristics; it is particularly well-suited for multi-output industrial power supplies, rack-mounted auxiliary power supplies and medical isolation power supplies. It is often used in conjunction with Renesas synchronous rectification controllers to further enhance the overall conversion efficiency of the system.

3. Typical Applications

Industrial switching power supplies, built-in power supplies for telecommunications equipment, medical isolation power supplies, high-power laser driver power supplies and multi-output auxiliary power supplies for servers.

[Non-isolated AC/DC Buck Converter]

1. Topology Overview

A non-isolated high-voltage AC-DC buck solution that directly steps down the high-voltage bus—derived from rectifying 85–265 V AC—to low-voltage DC. It requires no isolation transformer, resulting in a minimal BOM and compact form factor. Suitable only for on-board auxiliary power supplies inaccessible to humans; use as an external power adapter is strictly prohibited. Renesas’ flagship product line is the RAA2230xx series of integrated 700V MOS offline buck regulators.

2. Key Technical Highlights (RAA223011 / RAA223012 / RAA223021)

A single-chip integrated 700V high-voltage power MOSFET eliminates the need for an external high-voltage switch; the only required peripherals are an inductor, a capacitor and a small number of resistors.

Hybrid control strategy: Constant Off-Time (COT) control under heavy loads; automatic transition to Pulse Frequency Modulation (PFM) mode under light loads; switching frequency avoids the audible range, ensuring inaudible noise.

Built-in frequency jitter effectively suppresses EMI noise and reduces the requirement for X/Y capacitors and common-mode chokes.

Ultra-low standby power consumption: no-load power consumption is generally <10 mW, meeting the low-power requirements of modern household appliances and sensors; quiescent current is <100 μA.

Comprehensive built-in protection: input brown-out protection, output short-circuit hiccup protection (SCP), overload protection (OLP), open-loop feedback protection, and on-chip thermal shutdown (OTP).

Clear power rating hierarchy

RAA223012: Maximum 2.5W, ultra-compact TSOT23-5 package

RAA223011: Maximum 4W

RAA223021: Maximum 8W

Output voltage range: 3.3V to 54V for flexible design, directly powering MCUs, relays, sensors and communication modules.

3. Typical Applications

Smart home control power supplies, smoke/gas sensors, internal power supplies for electricity meters, auxiliary power supplies for white goods control boards, industrial transmitters, and internal auxiliary bias for off-line switching power supplies.