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參數資料
| 型號： | FSDL321L |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 穩壓器 |
| 英文描述： | Green Mode Fairchild Power Switch (FPS TM) |
| 中文描述： | 1.5 A SWITCHING REGULATOR, 55 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | SOP-8 |
| 文件頁數： | 11/20頁 |
| 文件大?。?/td> | 479K |
| 代理商： | FSDL321L |
FSDL0165RN
11
Figure 6. Over load protection
4.2 Thermal Shutdown (TSD)
:
The Sense FET and the
con-
trol IC are integrated, making it easier for the control IC to
detect the temperature of the Sense FET. When the tempera-
ture exceeds approximately 140
°
C, thermal
shutdown is acti-
vated.
4.3 Abnormal Over Current Protection (AOCP)
:
Figure 7. AOCP Function & Block
Even though the FPS
TM
has OLP (Over Load Protection)
and current mode PWM feedback, these are not enough to
protect the FPS
TM
when a secondary side diode short or a
transformer pin short occurs. In addition to start-up, soft-
start is also activated at each restart attempt during auto-
restart and when restarting after latch mode is activated. The
FPS
TM
has an internal AOCP (Abnormal Over Current Pro-
tection) circuit as shown in figure 7. When the gate turn-on
signal is applied to the power Sense FET, the AOCP block is
enabled and monitors the current through the sensing resis-
tor. The voltage across the resistor is then compared with a
preset AOCP level. If the sensing resistor voltage is greater
than the AOCP level, pulse by pulse AOCP is triggered
regardless of uncontrollable LEB time. Here, pulse by pulse
AOCP stops Sense FET within 350nS after it is activated.
4.4 Over Voltage Protection (OVP) :
In case of malfunc-
tion in the secondary side feedback circuit, or feedback loop
open caused by a defect of solder, the current through the
opto-coupler transistor becomes almost zero. Then, Vfb
climbs up in a similar manner to the over load situation, forc-
ing the preset maximum current to be supplied to the SMPS
until the over load protection is activated. Because excess
energy is provided to the output, the output voltage may
exceed the rated voltage before the over load protection is
activated, resulting in the breakdown of the devices in the
secondary side. In order to prevent this situation, an over
voltage protection (OVP) circuit is employed. In general,
Vcc is proportional to the output voltage and the FPS
TM
uses
Vcc instead of directly monitoring the output voltage. If
V
CC
exceeds 19V, OVP circuit is activated resulting in ter-
mination of the switching operation. In order to avoid undes-
ired activation of OVP during normal operation, Vcc should
be properly designed to be below 19V.
5. Soft Start
:
The FPS
TM
has an internal soft start circuit
that
increases the feedback voltage together with the Sense FET
current slowly after it starts up. The typical soft start time is
15msec, as shown in figure 8, where progressive increments
of Sense FET current are allowed during the start-up phase.
The pulse width to the power switching device is progres-
sively increased to establish the correct working conditions
for transformers, inductors, and capacitors. The voltage on
the output capacitors is progressively increased with the
intention of smoothly establishing the required output volt-
age. It also helps to prevent transformer saturation and
reduce the stress on the secondary diode.
1
t
2
t
3
t
4
t
t
3V
6V
Vcc
8V
Delay current (5uA) charges the Cfb
FPS switching
OLP
Following Vcc
2
_
,
8
,
3
)
t
(
);
)
R
(
1
1
1
fig
fb
fb
fb
C
C
K
R
V
V
t
V
In
RC
t
=
=
=
=
V
t
)
(
V
t
)
t
V
uA
5
I
I
t
V
t
)
t
V
(
C
t
delay
delay
fb
3
1
(
,
;
))
1
(
1
(
2
=
+
=
+
=
R
S
Q
Vsense
Vfb
Out Driver
Rsense
CLK
Drain
V
AOCP
PWM
COMPARATOR
AOCP
COMPARATOR
LEB
1mS
15steps
Current limit
0.98A
2.15A
t
Drain current
[A]
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相關代理商/技術參數 |
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| FSDL321L_Q | 功能描述:電源開關 IC - 配電 FPS for DVDP/STB RoHS:否 制造商:Exar 輸出端數量: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 |
| FSDLC01G-S | 制造商:AXIOMTEK 制造商全稱:AXIOMTEK 功能描述:Capacity: 128MB to 32GB |
| FSDLC128-S | 制造商:AXIOMTEK 制造商全稱:AXIOMTEK 功能描述:Capacity: 128MB to 32GB |
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