Fairchild FL7930B和FAN621S 150W LED街燈照明電源解決方案 - 全文

關鍵詞： Fairchild , FAN621S , FL7930B , LED , 街燈照明電源

Fairchild 公司的FL7930B是用于照明的單級反激和邊界模式PFC控制器，采用電壓PWM來產生MOSFET關斷信號。+500/-800mA峰值柵極驅動電流，并提供過壓，反饋開路，過流，輸入電壓缺失檢測和欠壓鎖住保護，主要用在鎮流器，通用LED照明，工業，商業和住宅區裝飾照明以及室外照明。本文介紹了FL7930主要特性，方框圖，幾種典型應用電路以及采用FL7930B和FAN7621S的150W LED開關電源參考設計主要指標，電路圖和材料清單。

FL7930：Single-Stage Flyback and Boundary-Mode PFC Controller for Lighting

The FL7930 is an active Power Factor Correction (PFC) controller for low-to high-power lumens applications that operate in Critical Conduction Mode (CRM). It uses a voltage-mode PWM that compares an internal ramp signal with the error amplifier output to generate a MOSFET turn-off signal. Because the voltage-mode CRM PFC controller does not need rectified AC line voltage information, it saves the power loss of an input voltage sensing network necessary for a current-mode CRM PFC controller.

FL7930 provides over-voltage, open-feedback, overcurrent, input-voltage-absent detection, and undervoltage lockout protections. The FL7930 can be disabled if the INV pin voltage is lower than 0.45V and the operating current decreases to a very low level.Using a new variable on-time control method, THD is lower than the conventional CRM boost PFC ICs.

The FL3930B provides an additional OVP pin that can be used to shut down the boost power stage when output voltage exceeds OVP level due to damaged resistors connected at the INV pin. The FL7930C provides a PFC-ready pin can be used to trigger other power stages when PFC output voltage reaches the proper level (with hysteresis).

FL7930主要特性：

 Additional PFC-Ready Function (FL7930C Only)

 Input-Voltage-Absent-Detection Circuit

 Maximum Switching Frequency Limitation

 Internal Soft-Start with Overshoot Prevention

 Internal Total Harmonic Distortion (THD) Optimizer

 precise Adjustable Output Over-Voltage Protection

 Additional OVP Detection Pin (FL7930B Only)

 Open-Feedback Protection and Disable Function

 Zero-Current Detector

 150μs Internal Startup Timer

 MOSFET Over-Current Protection (OCP)

 Under-Voltage Lockout with 3.5V Hysteresis

 Low Startup and Operating Current

 Totem-Pole Output with High State Clamp

 +500/-800mA Peak Gate Drive Current

 8-Pin Small Outline Package (SOP)

FL7930應用：

Ballast

General LED Lighting

Industrial, Commercial, and Residential Fixtures

Outdoor Lighting: Street, Roadway, Parking, Construction and Ornamental LED Lighting Fixtures

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圖1。FL7930B方框圖

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圖2。FL7930C方框圖

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圖3。FL7930B PFC應用電路圖

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圖4。FL7930B 單級反激轉換器應用電路圖

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圖5。FL7930C PFC應用電路圖

采用FL7930B和FAN7621S的150W LED開關電源參考設計

The following reference design supports inclusion of FEB-L013 in design of LED SMPS. It should be used in demo board with the FL7930B, FAN7621S and discrete datasheet as well as Fairchild’s application notes and technical support team.

150W LED開關電源參考設計主要指標：

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150W LED開關電源參考設計主要特性：

Constant-Voltage (C.V) and Constant-Current (C.C) Control with Secondary- Feedback Circuitry

Low EMI through zero current switching of PFC and zero voltage switching of DC-DC converter

precise Adjustable Ouput over-voltage Protection

Internal Soft start and overshoot-less control

Internal Total Harmonic Distortion (THD) Optimizer

Variable frequency control with 50% duty cycle for half-bridge resonant converter topology

Fixed dead time(350ns)

Up to 300kHz operating frequency

Auto-restart operation for all protections with an external LVCC

Low gate charge

Low Crss

Fast switching

100% avalanche tested

Improved dv/dt capability

ESD Improved capability

protection Functions: UVLO, Over-Voltage, Over-Current

This application note describes a 150W rating design guideline for LED street lighting. The application design consists of CRM PFC and LLC SRC with high power factor and high power conversion efficiency using FL7930B and FAN7621S. To verify the validity of the application board and scheme, a demonstration board 150W (103V/1.46A) AC-DC converter was implemented and its results are presented in this application note. In CRM active PFC, the most popular topology is a boost converter. This is because boost converters can have continuous input current that can be manipulated with peak current mode control techniques to force peak current to track changes in line voltage. The FAN7930B is an active Power Factor Correction (PFC) controller for boost PFC applications that operate in critical conduction mode (CRM). Since it was first introduced in early 1990s, LLC-SRC (series resonant converter) has became a most popular topology because of its outstanding performance in areas such as the output regulation of switching frequency, ZVS capability for entire load range, low turn-off current, small resonant components using the integrated transformer, zero current switching (ZCS), and no reverse recovery loss on secondary rectifier. Figure 1 shows the typical application circuit, with the CRM PFC converter in the front end and the LLC SRC DC-DC converter in the back end. FL7930B and FAN7621S achieve high efficiency with medium power for 150W rating applications where CRM and LLC SRC operation with a two-stage shows best performance. CRM boost PFC converters can achieve better efficiency with light and medium power rating than Continuous Conduction Mode (CCM) boost PFC converters. These benefits result from the elimination of the reverse-recovery losses of the boost diode and Zero-Current Switching (ZCS). The LLC SRC DC-DC converter achieves higher efficiency than the conventional hard switching converter. The FL7930B provides a controlled on-time to regulate the output DC voltage and achieves natural power factor correction. The FAN7621S includes a high-side gate driver circuit, accurate current-controlled oscillator, frequency -limit circuit, soft-start, and built-in protections.

The high-side gate drive circuit has a common-mode noise cancellation capability, which guarantees stable operation with excellent noise immunity. Using Zero Voltage Switching (ZVS) dramatically reduces switching losses and significantly improves efficiency. ZVS also reduces switching noise noticeably, which allows a small-sized Electromagnetic Interference (EMI) filter.