FSCM0465RJ Fairchild Semiconductor, FSCM0465RJ Datasheet - Page 11

• Manufacturer Part Number: FSCM0465RJ
• Description: IC SWIT PWM GREEN OVP HV D2PAK
• Manufacturer: Fairchild Semiconductor

Specifications of FSCM0465RJ

• Output Isolation: Isolated
• Frequency Range: 60 ~ 72kHz
• Voltage - Input: 8 ~ 20 V
• Voltage - Output: 650V
• Power (watts): 55W
• Operating Temperature: 25°C ~ 150°C
• Package / Case: TO-263-7, D²Pak (6 leads + Tab), TO-263CB
• Power Switch Family: FSCM0465R
• Input Voltage: 85 to 265V
• Power Switch On Resistance: 2.2Ohm
• Output Current: 2.3A
• Number Of Outputs: Single
• Mounting: Surface Mount
• Supply Current: 2.5mA
• Package Type: D2PAK
• Operating Temperature (min): -25C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Pin Count: 5 +Tab
• Power Dissipation: 140W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

FSCM0465R Rev. 1.0.1
© 2006 Fairchild Semiconductor Corporation
2.2 Constant Power Limit Circuit : Due to the circuit
delay of FPS, the pulse-by-pulse limit current increases
a little bit when the input voltage increases. This means
unwanted excessive power is delivered to the secondary
side. To compensate, the auxiliary power compensation
network in Figure 19 can be used. R
by-pulse current by absorbing internal current source
(I
between resistors. With the suggested compensation
circuit, additional current from I
proportionally to the input voltage (V
constant power in wide input range. Choose R
proper current to the application, then check the pulse-
by-pulse current difference between minimum and
maximum input voltage. To eliminate the difference (to
gain constant power), R
where, I
specification; N
and primary side, respectively; I
source at feedback pin with a typical value of 0.9mA; and
ΔI
eliminated. In case of capacitor in the circuit 1µF, 100V is
good choice for all applications.
FB
FSCM0465R Rev. 00
lim_comp
: typical value is 0.9mA), depending on the ratio
R
LIM
Figure 19. Constant power limit circuit
lim_spec
is the current difference which must be
Vfb
I_lim
a
R
and N
is the limit current stated on the
y
Drain
GND
≅
Vcc
I
lim_spec
p
y
I
fb
are the number of turns for V
can be calculated by:
×
V
R
ΔI
DC
Y
×
lim_comp
V
dc
fb
×
C
FB
is the internal current
Y
Np
N
N
LIM
L
a
p
Na
+
is absorbed more
-
DC
V
can adjust pulse-
compensation
network
y
) and achieves
=
V
DC
×
N
N
LIM
a
p
(3)
for
CC
11
2.3 Leading Edge Blanking (LEB) : At the instant the
internal SenseFET is turned on, a high-current spike
through the SenseFET usually occurs, caused by
primary-side capacitance and secondary-side rectifier
reverse recovery. Excessive voltage across the Rsense
resistor can lead to incorrect feedback operation in the
current mode PWM control. To counter this effect, the
FSCM0465R employs a leading edge blanking (LEB)
circuit. This circuit inhibits the PWM comparator for a
short time after the SenseFET is turned on.
3. Protection Circuit : The FSCM0465R has several
self-protective functions, such as overload protection
(OLP), over-voltage protection (OVP) and thermal
shutdown (TSD). Because these protection circuits are
fully integrated into the IC without external components,
the reliability is improved without increasing cost. Once
the fault condition occurs, switching is terminated and
the SenseFET remains off. This causes V
When V
current consumed by the FSCM0465R decreases to the
startup current (typically 20µA) and the current supplied
from the DC link charges the external capacitor (C
connected to the V
voltage of 12V, the FSCM0465R resumes normal
operation. In this manner, the auto-restart can alternately
enable and disable the switching of the power SenseFET
until the fault condition is eliminated (see Figure 20).
3.1 Overload Protection (OLP) : Overload is defined as
the load current exceeding a preset level due to an
unexpected event. In this situation, the protection circuit
should be activated to protect the SMPS. However, even
when the SMPS is in the normal operation, the overload
protection circuit can be activated during the load
FSCM0465R Rev. 00
Vds
Vcc
12V
8V
CC
Power
Figure 20. Auto Restart Operation
On
reaches the UVLO stop voltage of 8V, the
Operation
Normal
CC
occurs
pin. When V
Fault
Situation
Fault
removed
CC
Fault
reaches the start
www.fairchildsemi.com
Operation
Normal
CC
to fall.
t
a
)