MC34261 MC33261

10

MOTOROLA ANALOG IC DEVICE DATA

Figure 17. Power Factor Test Set–Up

0.005

1.0

0.005

HARM

FREQ

11

LO

0.1

O

I

T

0 to 270 Vac

Output Power Factor

Controller Circuit

Earth

Line

Neutral

115 Vac

Input

RFI Filter

Autoformer

2X Step–Up

Isolation

Transformer

LO

HI

HI

V

A

Ainst

Acf

Vcf

Arms

Vrms

PF

VA

W

13

9

7

5

3

2

1

0

Voltech

AC POWER ANALYZER

PM 1000

An RFI filter is required for best performance when connecting the preconverter directly to the AC line. Commercially available two stage filters

such as the Delta Electronics 03DPCG5 work excellent. The simple single stage test filter shown above can easily be constructed with a common

mode transformer. Transformer (T) is a Coilcraft CMT3–28–2 with 28 mH minimum inductance and a 2.0 A maximum current rating.

+

0.5 mA

2

1

Figure 18. Soft–Start Circuit

+

1.0M

To VCC

C

To VO

Startup overshoot can be eliminated with the

addition of a Soft–Start circuit.

Figure 19. Error Amp Compensation

2

C1

Error Amp

+

10

µA

R1

1

6

R2