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.
13 REF
ROFST
For FA5331 (Fig.10)
0.85•Ͱ ≤ ROFST(kΩ)≤ Ͱ
2
1
IIN–
C3
R5
C2
Rx
FA5331
IFB
(3.5•103–0.26•Rn)•12
where, Ͱ=ꢀ
42+0.26•Rn
and, Rn ≤ 100Ω
and, RX: don’t connect.
Rn
Current
16
IDET
detection
Cn
•You must not connect RX which reduces DC gain of current
error amplifier.
•You can connect R5 which is series with capacitor C3.
Fig.10
For FA5332 (Fig.11)
Rn ≤ 27Ω
and, RX: don’t connect.
13 REF
•You must not connect RX which reduces DC gain of current
error amplifier.
ROFST
•You can connect R5 which is series with capacitor C3.
•If you connect ROFST, dead time of AC input current will
extend.
2
1
IIN–
C3
R5
C2
Rx
FA5332
IFB
5. How to prevent from intermittent switching of low
frequency
An intermittent switching, which frequency is lower than 10Hz,
occurs in some applications.
Rn
Current
detection
16
IDET
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)
Cn
You must check the effect thoroughly because this intermittent
switching depends on load, temperature and input condition.
Fig.11
9
FUJI [ FUJI ELECTRIC ]
