- 您現(xiàn)在的位置：買賣IC網 > PDF目錄375930 > FSCM0465RG (Fairchild Semiconductor Corporation) Green Mode Fairchild Power Switch PDF資料下載
參數(shù)資料
| 型號： | FSCM0465RG |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Green Mode Fairchild Power Switch |
| 中文描述： | 綠色模式飛兆半導體功率開關 |
| 文件頁數(shù)： | 11/20頁 |
| 文件大?。?/td> | 457K |
| 代理商： | FSCM0465RG |
F
2006 Fairchild Semiconductor Corporation
FSCM0465R Rev. 1.0.1
www.fairchildsemi.com
11
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
LIM
can adjust pulse-
by-pulse current by absorbing internal current source
(I
FB
: typical value is 0.9mA), depending on the ratio
between resistors. With the suggested compensation
circuit, additional current from I
FB
is absorbed more
proportionally to the input voltage (V
DC
) and achieves
constant power in wide input range. Choose R
LIM
for
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
y
can be calculated by:
where,
I
lim
_spec
is the limit current stated on the
specification;
N
a
and
N
p
are the number of turns for V
CC
and primary side, respectively;
I
fb
is the internal current
source at feedback pin with a typical value of 0.9mA; and
Δ
I
lim_comp
is the current difference which must be
eliminated. In case of capacitor in the circuit 1μF, 100V is
good choice for all applications.
Figure 19. Constant power limit circuit
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
CC
to fall.
When V
CC
reaches the UVLO stop voltage of 8V, the
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
a
)
connected to the V
CC
pin. When V
CC
reaches the start
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).
Figure 20. Auto Restart Operation
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
a
lim_spec
dc
p
y
fb
lim_comp
N
N
I
V
R
I
Δ
I
×
×
(3)
Vfb
Drain
Vcc
GND
I_lim
V
DC
Np
Na
-
+
C
Y
R
Y
R
LIM
L
p
a
DC
y
N
N
V
V
×
=
compensation
network
FSCM0465R Rev. 00
Fault
Situation
8V
12V
Vcc
Vds
t
Fault
occurs
Fault
removed
Normal
Operation
Normal
Operation
Power
On
FSCM0465R Rev. 00
相關PDF資料 |
PDF描述 |
|---|---|
| FSCM0465RGWDTU | Green Mode Fairchild Power Switch |
| FSCM0465RI | Green Mode Fairchild Power Switch |
| FSCM0465RIWDTU | Green Mode Fairchild Power Switch |
| FSCM0465RJ | Green Mode Fairchild Power Switch |
| FSCM0465RJX | Green Mode Fairchild Power Switch |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| FSCM0465RGWDTU | 功能描述:電源開關 IC - 配電 SMPS Power Switch for Set Top Box RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻（最大值）:85 mOhms 開啟時間（最大值）:400 us 關閉時間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-5 |
| FSCM0465RI | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch |
| FSCM0465RIWDTU | 功能描述:電源開關 IC - 配電 FPS FOR LCD RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻（最大值）:85 mOhms 開啟時間（最大值）:400 us 關閉時間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-5 |
| FSCM0465RJ | 功能描述:電源開關 IC - 配電 FPS FOR LCD RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻（最大值）:85 mOhms 開啟時間（最大值）:400 us 關閉時間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-5 |
| FSCM0465RJX | 功能描述:電源開關 IC - 配電 POWER_CONVERSION RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻（最大值）:85 mOhms 開啟時間（最大值）:400 us 關閉時間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-5 |
發(fā)布緊急采購，3分鐘左右您將得到回復。