FSQ510MX Fairchild Semiconductor, FSQ510MX Datasheet - Page 11

• Manufacturer Part Number: FSQ510MX
• Description: IC SWIT PWM GREEN UVLO 7MLSOP
• Manufacturer: Fairchild Semiconductor

Specifications of FSQ510MX

• Output Isolation: Isolated
• Frequency Range: 94.3 ~ 132kHz
• Voltage - Input: 6.7 ~ 20 V
• Voltage - Output: 700V
• Power (watts): 9W
• Operating Temperature: -40°C ~ 130°C
• Package / Case: 8-MLSOP (7-Lead)
• On Resistance (max): 28 Ohms
• Maximum Operating Temperature: + 140 C
• Minimum Operating Temperature: - 40 C
• Maximum Power Dissipation: 1380 mW
• Mounting Style: SMD/SMT
• Supply Current: 0.8 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: FSQ510MXTR

© 2009 Fairchild Semiconductor Corporation
FSQ510, FSQ510H, and FSQ510M • Rev. 1.3.0
7.
minimize
Interference (EMI), the MOSFET turns on when the
drain voltage reaches its minimum value in VS
converters. Due to the Discontinuous Conduction Mode
(DCM) operation, the feedback voltage is not changed,
despite the DC link voltage ripples, if the load condition
is not changed. Since the slope of the drain current is
changed depending on the DC link voltage, the turn-on
duration of MOSFET is variable with the DC link voltage
ripples. The switching period is changed continuously
with the DC link voltage ripples. Not only the switching
at the instant of the minimum drain voltage, but also the
continuous change of the switching period, reduces
EMI. V
Typical products for VSC turn the MOSFET on when the
first valley is detected. In this case, the range of the
switching frequency is very wide as a result of the load
variations. At a very light-load, for example, the
switching frequency can be as high as several hundred
kHz. Some products for VSC, such as Fairchild’s
FSCQ-series, define the turn-on instant of SenseFET
change at the first valley into at the second valley, when
the load condition decreases under its predetermined
level. The range of switching frequency narrows
somewhat.
datasheet, such as:
http://www.fairchildsemi.com/pf/FS/FSCQ1265RT.html
The range of the switching frequency can be limited
tightly in FSQ-series. Because a kind of blanking time
(t
frequency has minimum and maximum values.
0.85V
0.75V
B
V
V
Vo
) is adopted, as shown in Figure 19, the switching
I
Vo
FB
ds
ds
set
Advanced
S
converters inherently scatter the EMI spectrum.
Figure 18. Burst-Mode Operation
switching
For
Valley
t
1
details,
Switching
disabled
loss
Switching
consult
t
2
and
t
3
Switching
disabled
an
Operation:
Electromagnetic
FSCQ-series
t
4
time
To
Once the SenseFET is enabled, the next start is
prohibited during the blanking time (t
blanking time, the controller finds the first valley within
the duration of the valley detection window time (t
(case A, B, and C). If no valley is found in t
internal SenseFET is forced to turn on at the end of t
(case
FSQ510M have minimum switching frequency of
94.3kHz and maximum switching frequency of 132kHz,
typically, as shown in Figure 20.
11
94.3kHz
132 kHz
104 kHz
Figure 20. Switching Frequency Range of the
mode
Bur st
D).
Figure 19. Advanced VS Operation
I
ds
I
DS
I
t
DS
B
Therefore,
When the resonant period is 2µs
=7.6µ s
I
DS
T
t
s
B
max
T
=7.6µs
t
B
s
t
Advanced Valley Switching
B
max
=7.6µs
T
T
=10.6 µs
=7.6µ s
A
T
s_A
s_B
=10.6 µs
s_C
FSQ510,
B
I
DS
t
W
C
I
=3µs
DS
FSQ510H,
I
DS
B
www.fairchildsemi.com
). After the
I
D
DS
A
B
C
frequency
D
Con stant
W
, the
P
and
o
W
W
B
)