FA5527 FUJI [Fuji Electric], FA5527 Datasheet - Page 15

• Manufacturer Part Number: FA5527
• Description: Fuji Switching Power Control IC
• Manufacturer: FUJI [Fuji Electric]

(1) Start-up circuit
AN-087E Rev.1.0
April-2011
9. Description of block circuits
circuits with maximum rated voltage of 500V.
VCC pin from the start-up circuit, charging the capacitor,
C2, connected to the VCC pin, increasing its voltage,
activating the IC, and the power supply starts operation.
approximately 6.8mA at Vcc=0V, decreases as Vcc
increases and becomes approximately 6.1mA at the
start-up voltage. A resistor is connected in series to the
VH pin to prevent the IC from being damaged due to
surge in AC and other lines.
pin to half-wave rectified AC input voltage and taking the
longest start-up time of the three ways of wiring. When
AC input voltage is turned off after the circuit changed to
a latch mode due to overload or overvoltage protection,
the latch mode can be reset in a relatively short time of
several seconds because a current is not supplied from
the VH pin.
AC input voltage, reducing start-up time to approximately
half as compared to half-wave rectification circuit shown
in Fig.1. The latch mode can be reset in a short time
same as in Fig.1 because AC input voltage is cut off.
smoothed AC input voltage, resulting in the shortest
start-up time of the three ways of wiring. In this way of
wiring, it takes time for the latch mode to be reset
because charged C1 voltage is applied to the VH pin
even if the IC have changed to the latch mode.
Depending on usage conditions, in general it takes
several minutes.
of the low-voltage malfunction-protective circuit and the
IC is activated, the start-up circuit is cut off and VH pin
input current becomes 25uA (typ.).
abnormal condition, the start-up circuit is activated
again, the latch condition is maintained and Vcc voltage
is held at approximately 23V. Here, FA5526/27/28
enters to the latch mode by overload or over-voltage,
but FA5536/37/38 does not enter to the latch mode
without an additional external circuit (See “9.-(8)/(9)
Overload
The FA5526/27/28/36/37/38 has built-in start-up
Wiring is shown in Figs.1 to 3.
When power is turned on, a current is supplied to the
The current supplied to the VCC pin from the VH pin is
Fig.1 shows the commonest wiring, connecting the VH
In Fig.2, the VH pin is connected to full-wave rectified
In Fig.3, the VH pin is connected to rectified and
When VCC pin voltage exceeds ON threshold voltage
When IC enters to the latch mode due to any
Fuji Electric Co., Ltd.
protection,”
“9.-(10)/(11)
FA5526/5527/5528/5536/5537/5538
Over-voltage
15
protection.” ).
Fig.1 Start-up circuit 1 (half wave)
Fig.2 Start-up circuit 2 (full wave)
Fig.3 Start-up circuit 3 (DC)
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