/a>PFC” title=”PFC”>PFC” title=”PFC”>PFC switching power supply controller, with boost or flyback converter mode. The PFC circuit in the device provides high PF, low THD and stable DC bus adjustment, with cycle-by-cycle overcurrent and output overvoltage protection, mainly used in switching power supplies, Electronic ballasts and LED drivers. This article introduces the main features, functional block diagrams, and typical application circuits of IRS2500 And PFC pre-adjustment circuit diagram, 80W PFC circuit diagram
And its material list.
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.
Main features of IRS2500:
• 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
Typical application of IRS2500:
• Switched Mode Power Supplies
• Electronic Ballasts
• LED Drivers
Figure 1. Functional block diagram of IRS2500
Figure 2. Typical application circuit of IRS2500
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.
Figure 3. IRS2500 PFC pre-regulation circuit diagram
Figure 4. IRS2500 80W PFC circuit diagram
80W PFC circuit bill of materials (BOM):
For details, see:
http://www.irf.com/product-info/datasheets/data/irs2500spbf.pdf
with
http://www.irf.com/technical-info/appnotes/an-1173.pdf
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