MC34261 Datasheet, PDF (10/13 Pages) Motorola, Inc – POWER FACTOR CONTROLLERS

2X Step−Up
Isolation
Line
Transformer
115 Vac
Input
Neutral
Autoformer
MC34261, MC33261
Figure 17. Power Factor Test Set−Up
AC POWER ANALYZER
PM 1000
HI
HI
IO
W VA PF Vrms Arms _A
0 1235
V
0.1
Vcf Acf Ainst FREQ HARM
7 9 11 13
LO
LO
Voltech
RFI Filter
T
0.005
1.0
0.005
0 to 270 Vac
Output Power Factor
Controller Circuit
Earth
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.
Figure 18. Soft−Start Circuit
+
0.5 mA
2
To V_O
1
+
C
1.0M
To V_CC
t_{Soft−Start} ≈ 9000C in μF
Startup overshoot can be eliminated with the
addition of a Soft−Start circuit.
Figure 19. Error Amp Compensation
10μA
Error
Amp
+
R₂
1
R₁
6
2
C₁
http://onsemi.com
10