FA5331P Datasheet, PDF (9/13 Pages) Fuji Electric – Bipolar IC For Power Factor Correction

FA5331P(M)/FA5332P(M)
4. No-load operation
The following condition should be meet to prevent from
overvoltage and audible noise during no-load or light-load
operation.
For FA5331 (Fig.10)
0.85•Ͱ ≤ ROFST(kΩ)≤ Ͱ
where, Ͱ=  ^{(3.5•103–0.26•Rn)•12}
42+0.26•Rn
and, Rn ≤ 100Ω
and, RX: don’t connect.
•You must not connect RX which reduces DC gain of current
error amplifier.
•You can connect R5 which is series with capacitor C3.
For FA5332 (Fig.11)
Rn ≤ 27Ω
and, RX: don’t connect.
•You must not connect RX which reduces DC gain of current
error amplifier.
•You can connect R5 which is series with capacitor C3.
•If you connect ROFST, dead time of AC input current will
extend.
5. How to prevent from intermittent switching of low
frequency
An intermittent switching, which frequency is lower than 10Hz,
occurs in some applications.
In this case, it is possible to prevent from this intermittent
switching to reduce feedback gain by decreasing the
resistance of R4. (See Fig. 2)
You must check the effect thoroughly because this intermittent
switching depends on load, temperature and input condition.
ROFST
13 REF
C3
2 IIN–
C2
Rx
R5
FA5331
1 _IFB
Current
detection
Rn
16 _IDET
Cn
Fig.10
ROFST
13 REF
C3
2 IIN–
C2
Rx
R5
FA5332
1 _IFB
Current
detection
Rn
16 _IDET
Cn
Fig.11
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