FSQ0465RBLDTU Fairchild Semiconductor, FSQ0465RBLDTU Datasheet - Page 16

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FSQ0465RBLDTU

Manufacturer Part Number
FSQ0465RBLDTU
Description
IC PWM/SENSEFET QRC TO-220F-6L
Manufacturer
Fairchild Semiconductor
Series
FPS™r
Datasheet

Specifications of FSQ0465RBLDTU

Output Isolation
Isolated
Frequency Range
48kHz ~ 67kHz
Voltage - Input
9 V ~ 20 V
Voltage - Output
650V
Power (watts)
70W
Operating Temperature
-25°C ~ 85°C
Package / Case
TO-220FL
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
FSQ0465RS/RB Rev. 1.0.1
© 2008 Fairchild Semiconductor Corporation
Figure 33. QRC Operation with Limited Frequency
One-shot
GateX2
FSQ0465 Rev. 00
V
AVS
V
gate
DS
I
DS
t
B
GateX2: Counting V
=15
t
I
B
triggering
DS
I
DS
=15
t
fixed
B
μ
=15
I
DS
s
μ
t
s
s
max
t
μ
t
s
t
B
max
s
B
=21
=15
1st or 2nd is depend on GateX2
t
t
t
s
s
=21
s
V
V
μ
μ
DS
DS
gate
s
s
μ
s
every 2 pulses independent on other signals .
V
V
DS
DS
I
V
DS
gate
fixed
Figure 35. Alternating Valley Switching (AVS)
I
DS
I
continued 2 pulses
DS
1st valley switching
t
I
W
DS
=6
FSQ0465 Rev. 00
μ
de-triggering
s
t
B
D
A
B
C
fixed
triggering
V
gate
continued another 2 pulses
t
16
B
2nd valley switching
8. AVS (Alternating Valley Switching): Due to the
quasi-resonant operation with limited frequency, the
switching frequency varies depending on input voltage,
load transition, and so on. At high input voltage, the
switching on time is relatively small compared to low
input voltage. The input voltage variance is small and the
switching frequency modulation width becomes small. To
improve the EMI performance, AVS is enabled when
input voltage is high and the switching on time is small.
Internally, quasi-resonant operation is divided into two
categories; one is first-valley switching and the other is
second-valley switching after blanking time. In AVS, two
successive occurrences of first-valley switching and the
other two successive occurrences of second-valley
switching is alternatively selected to maximize frequency
modulation. As depicted in Figure 34, the switching
frequency hops when the input voltage is high. The
internal timing diagram of AVS is described in Figure 35.
67kHz
59kHz
53kHz
48kHz
f
s
fixed
frequency
Constant
Figure 34. Switching Frequency Range
FSQ0465 Rev.00
CCM
Modulation frequency is approximately 17kHz.
1st valley- 2nd valley frequency modulation.
D
t
B
1st or 2nd is dependent on GateX2
Assume the resonant period is 2 s
C
Variable frequency within limited range
fixed
1st valley switching
AVS trigger point
t
B
B
DCM
V
gate
fixed
continued 2 pulses
AVS region
μ
t
A
B
www.fairchildsemi.com
17
19
21
V
15
1
1
μ
1
μ
μ
I N
1
s
μ
s
s
s

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