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Innovative PFC Solutions

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The Importance of Power Factor Correction in Off-line Power Supplies

Power Factor Correction (PFC) is utilized to shape the input current of off-line power supplies to maximize the real power available from the mains.  Ideally, the input current would be a perfect in-phase replica of the input voltage, reducing the current draw from the mains and thus minimizing losses and costs associated with the distribution and generation of the power.  This, along with minimized interference thanks to freedom from harmonics, enables the design of highly efficient power supplies that comply with today’s every-expending regulatory requirements.

ON Semiconductor offers PFC Controllers implementing innovative CCFF, VSFF, and FCCrM methods that provide significant light load efficiency improvements.  In addition, these methods enable the use of a smaller transformer when compared to the traditional Critical Conduction Mode (CrM) approach. For example in a 100W application with similar performance a CrM implementation requires a ~450 µH transformer whereas applications using ON Semiconductor solutions would require only ~300 µH.  The smaller size and improved light load efficiency make them a good fit for products required to meet new industry efficiency standards.  

Current Controlled Frequency Fold-back (CCFF)

CCFF reduces frequency when the instantaneous line current is below a present level, where switching losses are dominant.  Frequency decay rate is controlled for optimized efficiency.  

50% Load (115 V rms)

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Valley Synchronized Frequency Fold-back (VSFF)

With VSFF, the frequency is reduced when the control signal is below a preset level by adding a constant dead-time over the sinusoid.

50% Load (115 V rms)

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Frequency Clamped Critical Conduction Mode (FCCrM)

FCCrM firmly limits the frequency at a preset level.

50% Load (115 V rms)

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A full suite of evaluations boards along with users manuals, schematics, layout files, and BoMs are available to evaluate the efficiency and features of the devices for your application.  The graph below demonstrates the dramatically improved light-load efficiency observed with the evaluation boards.

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Evaluation Board

PFC Controller

Description

Mode

NCP1615GEVB

NCP1615

120W High Efficiency

CCFF

NCP1611GEVB

NCP1611

160W Low Profile

CCFF

NCP1612GEVB

NCP1612

160W Low Profile

CCFF

NCP1602BOOSTGEVB

NCP1602

160W Low Profile

VSFF

NCP1399ADPGEVB

NCP1602

150W Adapter

VSFF

NCP1399AIOGEVB

NCP1602

240W All-in-One

VSFF



Device

Package

HV Start-up

pfcOK Pin

Mode

PSM

Average Efficiency

Light Load THD

NCP1615

16-pin

Yes

Yes

CCFF

Yes

Best

Good

NCP1611

8-pin

No

No

CCFF

No

Best

Good

NCP1612

10-pin

Yes

Yes

CCFF

No

Best

Good

NCP1602

6-pin

No

No

VSFF

No

Good

Best

NCP1605

16-pin

Yes

Yes

FCCrM

No

Good

Good

Click on the devices above for RS offer

ON Semiconductor Channel Marketing

5 Aug 2016, 18:12