參數(shù)資料
型號(hào)： FSDM0265RN
廠(chǎng)商： FAIRCHILD SEMICONDUCTOR CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： Green Mode Fairchild Power Switch (FPSTM)
中文描述： 8 A SWITCHING REGULATOR, 73 kHz SWITCHING FREQ-MAX, PDIP8
封裝： MS-001BA, DIP-8
文件頁(yè)數(shù)： 10/20頁(yè)
文件大?。?/td> 904K
代理商： FSDM0265RN
FSDM0265RNB
10
Figure 6. Over Load Protection (OLP)
4.2 Thermal Shutdown (TSD)
: The Sense FET and the
control IC are integrated, making it easier for the control IC
to detect the temperature of the Sense FET. When the tem-
perature exceeds approximately 140
°
C, thermal shutdown is
activated.
4.3 Over Voltage Protection (OVP) :
In the event of a mal-
function in the secondary side feedback circuit, or an open
feedback loop caused by a soldering defect, the current
through the opto-coupler transistor becomes almost zero
(refer to Figure 5). Then, V
FB
climbs up in a similar manner
to the over load situation, forcing the preset maximum cur-
rent 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 volt-
age and the FPS uses Vcc instead of directly monitoring the
output voltage. If V
CC
exceeds 19V, OVP circuit is activated
resulting in termination of the switching operation. In order
to avoid undesired activation of OVP during normal opera-
tion, Vcc should be properly designed to be below 19V.
5. Soft Start
: The FPS has an internal soft start circuit that
slowly increases the feedback voltage together with the
Sense FET current after it starts up. The typical soft start
time is 15msec, as shown in Figure 7, where progressive
increments of the Sense FET current are allowed during the
start-up phase. The pulse width to the power switching
device is progressively increased to establish the correct
working conditions for transformers, inductors, and capaci-
tors. The voltage on the output capacitors is progressively
increased with the intention of smoothly establishing the
required output voltage. It also helps to prevent transformer
saturation and reduce the stress on the secondary diode.
Figure 7. Soft Start Function
6. Burst Operation :
In order to minimize power dissipation
in standby mode, the FPS enters burst mode operation. As
the load decreases, the feedback voltage decreases. As
shown in Figure 8, the device automatically enters burst
mode
when
the
feedback
V
BURH
(500mV). Switching still continues but the current
limit is set to a fixed limit internally to minimize flux density
in the transformer. The fixed current limit is larger than that
defined by V
FB
= V
BURH
and therefore, V
FB
is driven
down further. Switching continues until the feedback voltage
drops below V
BURL
(350mV). At this point switching stops
and the output voltages start to drop at a rate dependent on
the standby current load. This causes the feedback voltage to
rise. Once it passes V
BURH
, switching resumes. The feed-
back voltage then falls and the process repeats. Burst mode
operation alternately enables and disables switching of the
Sense FET and reduces switching loss in Standby mode.
voltage
drops
below
V
FB
t
3V
6V
Over Load Protection
t
12
= C
FB
×
(V(t
2
)-V(t
1
)) / I
DELAY
t
1
t
2
V
t
V
V
t
V
A
I
I
t
V
t
V
C
t
DELAY
DELAY
FB
6
)
(
,
3
)
(
,
5
;
)
(
)
(
2
1
1
2
12
=
=
=
=
μ
1ms
15steps
Current limit
0.3A
1.5A
t
Drain current
DRAIN
GND
R
sense
#6,7,8
#1
I
LIM
5V
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
FSDM0265RNB 功能描述:電源開(kāi)關(guān) IC - 配電 SMPS Power Switch Built-in Soft Start RoHS:否 制造商:Exar 輸出端數(shù)量:1 開(kāi)啟電阻（最大值）:85 mOhms 開(kāi)啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
FSDM0265RNC 功能描述:電源開(kāi)關(guān) IC - 配電 Green Mode FPS RoHS:否 制造商:Exar 輸出端數(shù)量:1 開(kāi)啟電阻（最大值）:85 mOhms 開(kāi)啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
FSDM0365RL 功能描述:電源開(kāi)關(guān) IC - 配電 POWER_CONVERSION RoHS:否 制造商:Exar 輸出端數(shù)量:1 開(kāi)啟電阻（最大值）:85 mOhms 開(kāi)啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
FSDM0365RLX 功能描述:電源開(kāi)關(guān) IC - 配電 POWER_CONVERSION RoHS:否 制造商:Exar 輸出端數(shù)量:1 開(kāi)啟電阻（最大值）:85 mOhms 開(kāi)啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
FSDM0365RN 功能描述:電源開(kāi)關(guān) IC - 配電 POWER_CONVERSION RoHS:否 制造商:Exar 輸出端數(shù)量:1 開(kāi)啟電阻（最大值）:85 mOhms 開(kāi)啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
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