FA5527 FUJI [Fuji Electric], FA5527 Datasheet - Page 27

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

(3) Protection using CS pin for FA5526/27/28
(4) Protection using CS pin for FA5536/37/38
4V zener diode. Externally forcing CS pin voltage to
increase to the threshold voltage, 8.5V, for the latch mode
allows the IC to stop its operation for protection.
4V zener diode, 84uA, shall be applied to the CS pin.
guide.
at an arbitrary voltage using the CS pin.
(3-1) Overvoltage detection on the secondary side
circuit on the secondary side to change the IC into the
latch mode.
(3-2) Detection of Vcc (1)
latch mode upon detecting Vcc overvoltage. In this case,
Vcc voltage is latched at approximately ZD+8.5V.
voltage of the low-voltage malfunction preventive circuit.
Otherwise, the IC cannot start.
(3-3) Detection of Vcc (2)
In this case, Vcc voltage is latched approximately at ZD
voltage.
voltage of the low-voltage malfunction preventive circuit.
Otherwise, the IC cannot start.
Over-Voltage Protection as latch mode. Fig.32 shows
the OVP latch circuit by primary side detection at VCC pin
and Fig.33 shows the OVP latch circuit by secondary side
detection through a optocoupler “PC”.
the switching is shut-down. Once the NPN transistor “Q2”
and “Q3” turn-on when the diode “ZD1” or optocoupler
“PC” supplies the current to resistor “R1” by detection of
Over-Voltage, PNP transistor “Q1” turns-on and “Q2” and
“Q3” are maintained in ON-State.
current of a diode ZD2 is cut VCC pin voltage decreases
below OFF threshold ( 9V ) .
AN-087E Rev.1.0
April-2011
When CS pin voltage is pulled down below 0.68V ( typ. ),
In steady operation, the CS pin voltage is clamped by a
In this case, a current of more than the sink capacity of
Set the input current to the CS pin at 1mA or less as a
The following shows examples of overvoltage protection
Fig.29 shows an example of an overload detection
Fig.30 shows a circuit where the IC is stopped in the
Use a ZD whose voltage is larger than the ON threshold
Fig.31 shows another circuit to detect Vcc overvoltage.
Use a ZD whose voltage is larger than the ON threshold
FA5536/37/38 does not include any latch function.
Therefore, the external latch circuit is necessary for
Then, CS pin voltage is maintained at low level until the
Fuji Electric Co., Ltd.
FA5526/5527/5528/5536/5537/5538
Fig.29 Over Voltage protection (1) for FA5526/27/28
Fig.30 Over Voltage protection (2) for FA5526/27/28
Fig.31 Over Voltage protection (3) for FA5526/27/28
Fig.32 Over Voltage protection (1) for FA5536/37/38
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