FSDM0565RELDTU Fairchild Semiconductor, FSDM0565RELDTU Datasheet - Page 13

• Manufacturer Part Number: FSDM0565RELDTU
• Description: IC PWM/SENSEFET 650V TO-220F-6
• Manufacturer: Fairchild Semiconductor
• Series: FPS™r

Specifications of FSDM0565RELDTU

• Output Isolation: Isolated
• Frequency Range: 60kHz ~ 72kHz
• Voltage - Input: 9 V ~ 20 V
• Voltage - Output: 650V
• Power (watts): 70W
• Operating Temperature: -25°C ~ 85°C
• Package / Case: TO-220-6 Full Pack Formed Leads
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

FSDM0465RE, FSDM0565RE, FSDM07652RE Rev. 1.0.2
© 2006 Fairchild Semiconductor Corporation
3.1 Overload Protection (OLP): Overload is defined as
the load current exceeding a pre-set level due to an
unexpected event. In this situation, the protection circuit
should be activated to protect the SMPS. Even when the
SMPS is in normal operation, the overload protection
circuit can be activated during the load transition. To
avoid this undesired operation, the overload protection
circuit is designed to be activated 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 SenseFET is limited, and therefore the
maximum input power is restricted with a given input
voltage. If the output consumes beyond 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 C
this condition, V
6V, when the switching operation is terminated, as
shown in Figure 20. The delay time for shutdown is the
time required to charge C
A 10 ~ 50ms delay time is typical for most applications.
FSDM0565RE Rev: 00
V
V
12V
FB
8V
CC
DS
). If V
Power
FB
Figure 19. Auto Restart Operation
on
exceeds 2.5V, D1 is blocked and the 3.5µA
operation
FB
Normal
continues increasing until it reaches
occurs
Fault
B
situation
from 2.5V to 6.0V with 3.5µA.
Fault
O
) decreases below the set
B
removed
slowly up to V
Fault
operation
Normal
CC
. In
t
13
3.2 Over-Voltage Protection (OVP): If the secondary
side feedback circuit were to malfunction or a solder
defect caused an opening in the feedback path, the
current through the opto-coupler transistor becomes
almost zero. In this event, V
to the overload situation, forcing the preset maximum
current to be supplied to the SMPS until the overload
protection is activated. Because more energy than
required is provided to the output, the output voltage may
exceed the rated voltage before the overload protection
is activated, resulting in the breakdown of the devices in
the secondary side. To prevent this situation, an over-
voltage protection (OVP) circuit is employed. In general,
V
FSDM0x65RE uses V
the output voltage. If V
activated, resulting in the termination of the switching
operation. To avoid undesired activation of OVP during
normal operation, V
3.3 Thermal Shutdown (TSD): The SenseFET and the
control IC are built in one package. This makes it easy
for the control IC to detect the heat generation from the
SenseFET. When the temperature exceeds ~150°C, the
thermal shutdown is activated.
4. Soft-Start: The FSDM0x65RE has an internal soft-
start circuit that increases PWM comparator inverting
input voltage, together with the SenseFET current,
slowly after it starts up. The typical soft-start time is
10ms. The pulse width to the power switching device is
progressively increased to establish the correct working
conditions for transformers, inductors, and capacitors.
The voltage on the output capacitors is progressively
increased with the intention of smoothly establishing the
required output voltage. It also helps prevent transformer
saturation and reduces the stress on the secondary
diode during start-up.
CC
6.0V
2.5V
V
FB
is proportional to the output voltage and the
Figure 20. Overload Protection
T
1
CC
CC
CC
should be designed below 19V.
T
Overload protection
12
= C
exceeds 19V, an OVP circuit is
instead of directly monitoring
FB
FB
*(6.0-2.5)/I
climbs in a similar manner
delay
FSDM0565RE Rev: 00
www.fairchildsemi.com
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2
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