IR IRS2500 80W PFC开关电源解决方案

发布时间：2011-12-1 17:40 发布者：1046235000

IR公司的IRS2500是全集成全保护的PFC开关电源控制器,具有升压或反激转换器模式.器件中的PFC电路在各种线路/负载范围内提供高PF,低THD和稳定的DC总线调整,具有逐个周期的过流和输出过压保护,主要用在开关电源,电子镇流器和LED驱动器.本文介绍了IRS2500主要特性, 功能框图, 典型应用电路以及PFC预调整电路图, 80W PFC电路图
及其材料清单.

The IRS2500 is a fully integrated, fully protected PFC SMPS control IC designed to drive Boost or Flyback switching regulators providing high power factor. Typical applications are PFC pre-regulators for SMPS and electronic ballasts for fluorescent or HID lighting as well as single stage Flyback converters widely used in low power LED drivers. The IRS2500 is pin compatible with most industry standard critical counduction or transition mode PFC control IC with additional improvements to increase performance. The PFC circuitry provides high PF, low THD and stable DC bus regulation over a wide line/load range. The IRS2500 protection features include cycle by cycle over-current protection and output over voltage protection.

IRS2500主要特性:

• PFC Control IC

• Boost or Flyback Converter Modes

• Critical-conduction / Transition mode operation

• Over-current protection

• Static and Dynamic DC bus overvoltage protection

• Micropower startup (<50μA)

• Low quiescent current (2.5mA)

• Latch immunity and ESD protection

• Wide range PFC for universal AC line input

• Low THD

• Open load Over voltage protection

• Noise immunity

IRS2500典型应用:

• Switched Mode Power Supplies

• Electronic Ballasts

• LED Drivers

图1.IRS2500功能框图

图2.IRS2500典型应用电路

Many offline applications require power factor correction circuitry in order to minimize transmission line losses and stress on electrical generators and transformers created by high harmonic content and phase shift. Appliances often incorporate switching power supplies (SMPS) which include capacitive filter circuitry followed by a bridge rectifier and bulk capacitor supplying a load.

Without power factor correction circuitry a SMPS draws a high peak current close to the line voltage peak and almost no current over much of the cycle, resulting in a power factor of around 0.5 and a high total harmonic distortion.

Power factor correction circuitry is added which enables the appliance to draw a sinusoidal current from the AC line with negligible phase shift and very low harmonic distortion. This allows optimization of the load seen by the power grid such that power can be supplied without creating additional conductive losses in transmission lines or additional burden on transformers and generators. Costs to electricity providers are therefore reduced, which are hopefully passed on to the consumer.

Although not explicitly specified in standards such as IEC 61000-3-2 relating to power factor and line current harmonics, it is generally a requirement for the total harmonic distortion (THD) of the line input current supplying a PFC pre-regulator to be as low as possible. As is normally the case a tradeoff exists between cost and performance where more expensive high end products rated at higher power typically incorporate active power factor correction circuits, while low cost passive circuits often suffice in cheaper consumer products.

This is a market trend in power supplies used in a variety of appliances as well as electronic lighting ballasts for Fluorescent, high intensity discharge (HID) lamps and LED lighting.

For a product incorporating active power factor correction a THD of less than 20% over a wide input voltage range, normally 100VAC to 305VAC is expected.In many cases THD can be less than 10% over much or all of this voltage range.

The IRS2500 based PFCpre-regulator does not provide galvanic isolation of the output from the line input. Therefore if the system is supplied directly from a non-isolated input, an electrical shock hazard exists.The DC output voltage is highenough to produce a potentially lethal electrical shock!

It is recommended that for laboratory evaluation that the IRS2500PFC board be used with an isolated AC or DC input supply. The IRS2500 series Boost topology is suitable only for front end applications where isolation is either not necessary or provided elsewhere in the system.