FSQ0365RN Fairchild Semiconductor, FSQ0365RN Datasheet - Page 13

• Manufacturer Part Number: FSQ0365RN
• Description: IC SWIT PWM GREEN OVP UVLO 8DIP
• Manufacturer: Fairchild Semiconductor

Specifications of FSQ0365RN

• Output Isolation: Isolated
• Frequency Range: 50.5 ~ 95.2kHz
• Voltage - Input: 8 ~ 20 V
• Voltage - Output: 650V
• Power (watts): 25W
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• On Resistance (max): 4.5 Ohms
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 25 C
• Maximum Power Dissipation: 1500 mW
• Mounting Style: Through Hole
• Supply Current: 3 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

FSQ0365, FSQ0265, FSQ0165, FSQ321, FSQ311 Rev. 1.0.5
© 2006 Fairchild Semiconductor Corporation
4. Protection Circuits: The FSQ-series has several
self-protective functions, such as Overload Protection
(OLP), Abnormal Over-Current protection (AOCP), Over-
Voltage Protection (OVP), and Thermal Shutdown
(TSD). All the protections are implemented as auto-
restart mode. Once the fault condition is detected,
switching is terminated and the SenseFET remains off.
This causes V
Under-Voltage Lockout (UVLO) stop voltage of 8V, the
protection is reset and start-up circuit charges V
capacitor. When the V
12V, the FSQ-series resumes normal operation. If the
fault condition is not removed, the SenseFET remains off
and V
auto-restart can alternately enable and disable the
switching of the power SenseFET until the fault condition
is eliminated. Because these protection circuits are fully
integrated into the IC without external components, the
reliability is improved without increasing cost.
4.1 Overload Protection (OLP): Overload is defined as
the load current exceeding its normal level due to an
unexpected abnormal event. In this situation, the
protection circuit should trigger to protect the SMPS.
However, even when the SMPS is in the normal
operation, the overload protection circuit can be
triggered during the load transition. To avoid this
undesired operation, the overload protection circuit is
designed to trigger only after a specified time to
determine whether it is a transient situation or a true
overload situation. Because of the pulse-by-pulse
current limit capability, the maximum peak current
through the Sense FET is limited, and therefore the
maximum input power is restricted with a given input
FSQ0365RN Rev. 00
V
V
12V
8V
DS
CC
Figure 23. Auto Restart Protection Waveforms
CC
Power
drops to stop voltage again. In this manner, the
on
CC
operation
Normal
to fall. When V
occurs
Fault
CC
reaches the start voltage of
situation
Fault
removed
CC
Fault
falls down to the
operation
Normal
t
CC
13
voltage. If the output consumes more than this maximum
power, the output voltage (V
voltage. This reduces the current through the opto-
coupler LED, which also reduces the opto-coupler
transistor current, thus increasing the feedback voltage
(V
current source starts to charge CB slowly up to V
this condition, V
6V, when the switching operation is terminated, as
shown in Figure 24. The delay time for shutdown is the
time required to charge CB from 2.8V to 6V with 5µA. A
20 ~ 50ms delay time is typical for most applications.
4.2 Abnormal Over-Current Protection (AOCP): When
the secondary rectifier diodes or the transformer pins are
shorted, a steep current with extremely high-di/dt can
flow through the SenseFET during the LEB time. Even
though the FSQ-series has OLP (Overload Protection), it
is not enough to protect the FSQ-series in that abnormal
case, since severe current stress is imposed on the
SenseFET until OLP triggers. The FSQ-series has an
internal AOCP (Abnormal Over-Current Protection)
circuit as shown in Figure 25. When the gate turn-on
signal is applied to the power SenseFET, the AOCP
block is enabled and monitors the current through the
sensing resistor. The voltage across the resistor is
compared with a preset AOCP level. If the sensing
resistor voltage is greater than the AOCP level, the set
signal is applied to the latch, resulting in the shutdown of
the SMPS.
6.0V
2.8V
V
FB
FB
Figure 25. Abnormal Over-Current Protection
FSQ0365RN Rev.00
). If V
3R
R
FB
Figure 24. Overload Protection
AOCP
exceeds 2.8V, D1 is blocked and the 5µA
t
PWM
1
OSC
FB
continues increasing until it reaches
200ns
LEB
Overload protection
t
12
= C
S
R
FB
Q
Q
O
*(6.0-2.8)/I
+
) decreases below the set
-
V
driver
Gate
OCP
FSQ0365RN Rev.00
delay
R
sense
www.fairchildsemi.com
1
GND
t
CC
2
. In
t