FA5331 Fuji Electric holdings CO.,Ltd, FA5331 Datasheet - Page 5

• Manufacturer Part Number: FA5331
• Description: Bipolar Ic For Power Factor Correction Electric
• Manufacturer: Fuji Electric holdings CO.,Ltd

Vo = R1 + R2
FA5331P(M)/FA5332P(M)
1. Oscillator section
This section outputs sawtooth waves oscillating between 0.15
and 3.55V using the capacitor charge and discharge
characteristics. Figure 1 shows how to connect the required
external components to this circuit. The oscillation frequency
is determined by the C
between the C
curves. Pin 14 (SYNC) is a synchronizing input terminal
whose threshold voltage is about 1V. As Fig. 1 shows, input
rectangular synchronizing signal waves to pin 14 through an
RC circuit. Set the free-running frequency about 10% lower
than the synchronizing signal frequency. Connect a clamp
diode (D1) to prevent an unwanted current inside the IC.
2. Voltage error amplifier and overvoltage limiting circuit
The voltage error amplifier forms a voltage feedback loop to
keep the output voltage stable. The positive input terminal of
this amplifier is connected to the reference voltage (Vr). Fig. 2
shows how to connect the required external components to
this circuit.
The output voltage (Vo) is as follows:
FA5331: Vr=1.54V(typ.)
FA5332: Vr=1.55V(typ.)
Connect a resistor and a capacitor in parallel across error
amplifier output pin 5 and error amplifier negative input pin
6 to set the voltage gain (Av).
The Av value is as follows:
Error amplifier cutoff frequency (fc) is as follows:
fc =
If 100 or 120Hz ripples appear at the error amplifier output, the
active filter does not operate stably. To ensure stable
operation, set the fc value to about 1Hz.
An overvoltage detection comparator (C1) is built in to limit the
voltage if the output voltage exceeds the design value. The
reference input voltage (Vp) is as follows:
Vp =
The connections shown in Fig. 2 limit the output voltage to
times the design value.
5
............................................................................... (1)
Av =
=1.065
Description of each circuit
2 C1 • R4
R3 ( 1 + j C1 • R4 )
• Vr ............................................................. (4)
R1
1
T
R4
and R
• Vr
................................................. (3)
T
T
values is shown in characteristic
and R
T
............................... (2)
values. The relationship
R2
R1
Fig. 2 Voltage error amplifier and overvoltage limiting circuit
Vo
R3
R4
R
Fig. 1 Oscillator
C1
CT
Csy
RT
5
6
4
D1
Vp
13 REF
15
14
Vr
CT
SYNC
+
_
A1
C1
ER.AMP
OVP
OSC
MUL
F.F