中国电子技术网

设为首页 网站地图 加入收藏

 

[原创] Infineon IRS2505L+IRS29875W LED参考设计IRXLED10

关键词:电源管理 LED驱动器 IRXLED10

时间:2020-01-02 10:49:27       来源:中电网

infineon公司的IRXLED10是75W两级非调光LED驱动器参考设计,拓扑包括功率因素修正(PFC)升压转换器前端IRS2505L控制器和严格调整的恒流(CC)稳压降压LED驱动器IRS2982.IRS2505L是临界导通模式(CrCM) PFC控制器,可用在高达150W的电源和照明应用.基于IRS2505L的升压PFC预转换器能满足EN 61000-3-2规范,包括照明应用的C类限值.某些条件下,它能用在开关电源(SMPS)拓扑如降压,降压-升压和反激.IRS2982 LED驱动器提供精密控制的电流和保护,免受过载对LED的损害.参考设计IRXLED10的AC输入电压从90 V AC到高达265 V AC (55 - 65 Hz),输出电压在360 mA +/-1.5 mA电流为60到200 V DC,最大输出连续功率为75W,最大负载和90 - 265 V AC输入电压时PF大于0.9,总谐波失真((iTHD)小于20%,效率大于90%.本文介绍了75W LED驱动器参考设计IRXLED10主要特性和指标,电路图,材料清单和PCB设计图.

The IRS2505L is a CrCM boost PFC controller IC. All of the functionality for controlling the PFC pre-converter is integrated into the SOT23-5 package. This low pin count solution operates by using multi-functional VBUS and PFC pins so that the cycle-by-cycle Current Sense (CS) input is combined with the output voltage feedback at the VBUS pin and the Zero Crossing (ZC) sensing function is combined with the gate drive at the PFC pin.

At the start of each switching cycle the PFC pin gate drive output pulls the PFC pin voltage high and the external MOSFET turns on, where the on-time duration is set by the (CMP) pin voltage. The internal PFC control loop regulates the CMP pin voltage, which determines the on-time such that if the DC bus voltage increases then the CMP pin voltage and on-time will decrease, and vice versa. Decreasing the on-time reduces the peak inductor current, transferring less energy per switching cycle and causing the DC bus voltage to decrease. If the DC bus voltage decreases below the desired level the CMP pin voltage, on-time will increase to compensate. This negative feedback control loop regulates the DC bus to a constant voltage over AC-line voltage or output load variations. The speed of regulation is determined by the internal OTA trans-conductance and compensation capacitor CCMP.

At the end of each on-time period, the PFC pin gate drive circuit pulls the PFC pin to COM and the external PFC MOSFET turns off. After a short initial switch-off delay (tPD), the IRS2505L internal gate drive pull-down turns off and the PFC pin is then weakly pulled up and clamped at approximately one diode forward voltage drop (VPFCOFF), which is well below the gate threshold of the MOSFET (MPFC), ensuring that it is not able to switch on. During the off-time the PFC inductor current discharges through the boost diode into the DC output capacitor and load. When the inductor current falls to zero, the drain voltage falls from the level of the output voltage plus the output diode forward voltage, and transitions negatively. During this transition current flows through the MOSFET parasitic gate-to-drain capacitance CGD, overcoming the internal weak pull-up and causing the gate voltage to drop below the threshold VPFCZC-. After remaining below this threshold for a period of tZCBLANK, the PFC gate drive is turned on again to begin the next switching cycle. To ensure ZC Detection (ZCD) a minimum voltage headroom of 60 to 70 V is needed between the peak line voltage at high-line and the output voltage. This value depends on the MOSFET CGD and CGS values. To operate with smaller headroom a 500 V minimum rated capacitor of low value in the tens of pF range may be added between drain and gate with a 100 Ω series resistor to provide some additional -dv/dt coupling to the gate.

Since the loop speed is slow with respect to the line frequency, the on-time is essentially constant over the entire half-cycle of the line input voltage, producing a peak inductor current that naturally follows the sinusoidal shape of the line input voltage. The filtered, averaged line input current is in phase with the line input voltage (neglecting a small displacement caused by the input filter X-capacitors) to provide high power factor. However some harmonic distortion of the current is still present, mostly due to cross-over distortion occurring near the ZCs of the line input voltage. To achieve very low harmonics within the limits of international standards and to meet general market requirements, on-time modulation is included in the IRS2505L, which dynamically increases the on-time as the line input voltage nears the ZCs. The peak LPFC current and therefore the smoothed line input current increase slightly near the ZCs of the line input voltage. This reduces the amount of cross-over distortion in the line input current and improves the shape of the current, reducing the iTHD and harmonics to low levels.

The VBUS input includes output OVP. Should the average feedback voltage at the VBUS pin exceed the internal OVP threshold (VBUSOV+) then the PFC gate drive will turn off until the VBUS pin voltage again falls below the OV restart threshold (VBUSOV-) to resume normal operation. As well as sensing the output voltage feedback, the VBUS input also includes a cycle-by-cycle, AC-coupled, OCP function. An internal OCP circuit detects the difference between the peak and average of the composite signal such that if the triangular-shaped voltage peak at the VBUS input exceeds VBUSREG by a delta of VBUSOC+ the gate drive is immediately driven low. Capacitor CVBUS is included in the feedback network to make the CS signal more triangular rather than a discontinuous ramp. This is so that the peak value will be close to half the average.

75W LED驱动器参考设计IRXLED10

The IRXLED10 reference design is a 75 W rated two-stage non-dimmable LED driver solution. The topology consists of a Power Factor Correction (PFC) boost converter front end based on the IRS2505L controller IC, followed by a tightly regulated Constant Current (CC) regulated buck LED driver based on the IRS2982. The IRS2505L is a Critical Conduction Mode (CrCM) PFC controller IC primarily intended for front-end PFC pre-regulators and typically used in power supply and lighting applications up to 150 W. The IRS2505L-based boost PFC pre-converter is able to meet the requirements of EN 61000-3-2, including class C limits for lighting applications. In some cases it is also appropriate to use this controller in other SMPS topologies such as buck, buck-boost and flyback. The back-end buck stage in this LED driver is configured for CC regulation using the IRS2982 controller operating in CrCM. The IRS2982 LED driver IC provides an accurately controlled current and protects the LEDs against damage from over-load.

The design procedure for the PFC stage based on the IRS2505L differs slightly from the procedure used for industry-standard 8-pin CrCM PFC control ICs, and will be explained in detail here. In order for the circuit to produce optimum performance care must be taken to select the correct component values and ratings. The PCB must also be designed according to correct practices for SMPS design, for which guidelines are provided, to avoid ground loops and noise susceptibility.


图1.75W LED驱动器参考设计IRXLED10外形图

75W LED驱动器参考设计IRXLED10指标:

Input and output at normal operation
 AC input voltage 90 V AC up to 265 V AC (55 to 65 Hz)
 Output voltage range at 360 mA +/-1.5 mA output 60 to 200 V DC
 Maximum output continuous power 75 W
 PF greater than 0.9 at maximum load, 90 to 265 V AC input voltage
 Total Harmonic Distortion (iTHD) less than 20 percent at maximum load, 90 to 265 V AC input voltage
 Efficiency greater than 90 percent at maximum load, 115 and 230 V AC input voltage
 Start-up time to reach the secondary nominal output voltage during full-load condition and 115 and 230 V AC input voltage less than 1.2 s
Protection features
 Primary output Over Voltage Protection (OVP) at VOUT less than or equal to 255 V DC
 Cycle-by-cycle primary Over Current Protection (OCP)
No-load operation
 Burst mode during no-load condition
 Max.power losses during no-load condition less than 500 mW, 120 and 230 V AC input voltage Max. component temperature
During worst-case scenario (ambient temperature 60℃) the max.allowed component temperature is:
 Resistor less than 100℃
 Ceramic capacitor, film capacitor and electrolytic capacitor less than 85℃
 Flyback transformer and chokes less than 100℃
 MOSFET, transistor and diodes less than 100℃
 IC less than 100℃
Dimensions of evaluation board
 Max.width 5.75 inches (146.0 mm), max. length 1.48 inches (37.8 mm)

图2.参考设计IRXLED10前端电路(PFC升压)

图3.参考设计IRXLED10后端电路(降压)
参考设计IRXLED10材料清单(BOM):




图4.参考设计IRXLED10 PCB设计图:顶层元件和走线

图5.参考设计IRXLED10 PCB设计图:底层元件和走线

图6.参考设计IRXLED10 PCB设计图:PCB布局
详情请见:
https://www.infineon.com/dgdl/Infineon-LED_current_regulated_two_stage_PFC-AN-v01_00-EN.pdf?fileId=5546d46266a498f50166e38dd77926e6
https://www.infineon.com/dgdl/Infineon-IRS2982S-DS-v11_01-EN.pdf?fileId=5546d462533600a40153567b886d2850
Infineon-IRS2982S-DS-v11_01-EN.pdf
Infineon-LED_current_regulated_two_stage_PFC-AN-v01_00-EN.pdf

  • 分享到:

 

猜你喜欢