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參數(shù)資料
| 型號(hào)： | SI9117 |
| 廠商： | Vishay Intertechnology,Inc. |
| 英文描述： | High-Frequency Converter for Telecom Applications |
| 中文描述： | 高頻轉(zhuǎn)換器的電信應(yīng)用 |
| 文件頁數(shù)： | 9/15頁 |
| 文件大小： | 132K |
| 代理商： | SI9117 |
Si9117
Vishay Siliconix
Document Number: 70027
S-40750—Rev. E, 19-Apr-04
www.vishay.com
9
UV-Low
Q
R
S
20 A
V
CC
6
5
4
3
2
1
NC
OP
+OP
TL431
Si9117
V
OUT
FIGURE 2.
Shutdown
Reference
The reference voltage is a fully buffered band gap type which
can source 5 mA over the specified voltage tolerance range.
The reference should be well de-coupled to prevent instability
and jitter. A ceramic 100-nF or small tantalum is
recommended, depending on the de-coupling present on the
supply pins.
Error Amplifier
The error amplifier consists of a PMOS input folded cascade
gain stage followed by a class AB unity gain amplifier. Typical
open loop voltage gain is 77 dB, and unity gain bandwidth is
typically 2.7 MHz. The soft-start circuit (see Pin 1 description)
forces the output to within 0.7 V above ground, and additional
clamp diodes limit the positive output excursion to within
2xV
BE
above V
REF .
Operation at high frequency allows high
closed loop bandwidths and permits excellent transient
response to both input and output changes. Under normal
operation, a small 100-pF bypass capacitor is recommended
from N
INV
to Comp to increase high-frequency noise rejection.
This should be calculated, however, in conjunction with the
loop dynamics.
Soft-Start
The soft-start circuit is designed to help dc-to-dc converters
start in an orderly manner and reduce component stress. The
output of the error amplifier is clamped by a PNP transistor.
The external capacitor C
SS
is supplied by a 20- A current
source and will charge linearly to 4.6 V. In the event of an
under-voltage lockout (or during start-up), this capacitor is held
low. Soft-start is a very important feature and has many
beneficial effects, especially in applications connecting to
telecom lines where source impedances are high. In such
cases, there is an initial start-up current caused by the input
capacitor, followed by a secondary peak caused by the
converter running at maximum duty cycle while trying to reach
regulation. Where large output capacitances and peak loads
are encountered, oscillations may occur. These can be
prevented with the use of long soft-start times. The soft-start
pin can also be used as a non-latching shutdown pin by
connecting it to
V
IN
. This approach allows a shutdown with
soft re-start.
+
FBK
NINV
Soft-
Start
1.5 k
Comp
FIGURE 3.
Operational Amplifier
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| SI9117DY | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 1MHz HV Sw Mode Reg RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| SI9117DY-E3 | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Hi Freq Converter For Telecom App RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| SI9117DY-T1 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Hi Freq Converter For Telecom App RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| SI9117DY-T1-E3 | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Hi Freq Converter For Telecom App RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| SI9118 | 制造商:VISHAY 制造商全稱:Vishay Siliconix 功能描述:Programmable Duty Cycle Controller |
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