FSFR2100 Fairchild Semiconductor, FSFR2100 Datasheet - Page 11

• Manufacturer Part Number: FSFR2100
• Description: IC SWIT PROG OVP OCP 9SIP
• Manufacturer: Fairchild Semiconductor
• Series: FPS™r

Specifications of FSFR2100

• Output Isolation: Isolated
• Frequency Range: 94kHz ~ 106kHz
• Voltage - Input: 9.6 V ~ 25 V
• Voltage - Output: 500V
• Power (watts): 400W
• Operating Temperature: -40°C ~ 130°C
• Package / Case: 9-SIP
• Output Voltage: 24 V
• Output Current: 8.3 A
• Output Power: 450 W
• Switching Frequency: 300 KHz
• Operating Temperature Range: - 40 C to + 130 C
• Mounting Style: Through Hole
• Duty Cycle (max): 52 %
• Isolated/non-isolated: Isolated
• For Use With: FEB212 - BOARD EVAL FOR FSFR2100
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

© 2007 Fairchild Semiconductor Corporation
FSFR2100 • Rev.1.0.8
5. Current Sensing
Current Sensing Using Resistor: FSFR2100 senses
drain current as a negative voltage, as shown in Figure
24 and Figure 25. Half-wave sensing allows low power
dissipation in the sensing resistor, while full-wave
sensing has less switching noise in the sensing signal.
Current Sensing Using Resonant Capacitor Voltage:
For high-power applications, current sensing using a
resistor may not be available due to the severe power
dissipation in the resistor. In that case, indirect current
sensing using the resonant capacitor voltage can be a
good alternative because the amplitude of the resonant
capacitor voltage (V
current in the primary side (I
To minimize power dissipation, a capacitive voltage
divider is generally used for capacitor voltage sensing, as
shown in Figure 26.
V
Cr
p p
−
=
2
I
π
V
V
CS
p
CS
Figure 24. Half-Wave Sensing
Figure 25. Full-Wave Sensing
p p
f C
R
−
s
sense
CS
CS
r
Control
Control
SG
SG
IC
IC
cr
Ids
p-p
Ids
PG
) is proportional to the resonant
PG
R
p
Cr
p-p
sense
Cr
Np
) as:
V
I
V
I
ds
Np
ds
CS
CS
Ns
Ns
Ns
Ns
(6)
11
6. Protection Circuits
The FSFR2100 has several self-protective functions,
such as Overload Protection (OLP), Over-Current
Protection (OCP), Abnormal Over-Current Protection
(AOCP), Over-Voltage Protection (OVP), and Thermal
Shutdown (TSD). OLP, OCP, and OVP are auto-restart
mode protections; while AOCP and TSD are latch-mode
protections, as shown in Figure 27.
6.1
condition is detected, switching is terminated and the
MOSFETs remain off. When LV
voltage of 11.3V, the protection is reset. The FPS
resumes normal operation when LV
voltage of 14.5V.
V
V
CON
I
sense
p
V
Figure 26. Current Sensing Using Resonant
Cr
Auto-restart Mode Protection: Once a fault
V
V
sense
Cr
p p
−
pk
Capacitor Voltage
=
C
sense
C
T
B
delay
+
C
B
=
R C
d
d
CC
V
sense
2
falls to the LV
pk
CC
=
reaches the start
V
CON
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CC
V
V
V
sense
sense
stop
Cr
p-p
pk
pk