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參數資料
| 型號： | FSDH0270RNB |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 穩壓器 |
| 英文描述： | Green Mode Fairchild Power Switch (FPSTM) |
| 中文描述： | 8 A SWITCHING REGULATOR, 108 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封裝： | MS-001BA, DIP-8 |
| 文件頁數： | 12/19頁 |
| 文件大小： | 608K |
| 代理商： | FSDH0270RNB |
12
www.fairchildsemi.com
FSDH0170RNB/FSDH0270RNB/FSDH0370RNB Rev. 1.0.2
F
Application Tips
1. Methods of Reducing Audible Noise
Switching mode power converters have electronic and
magnetic components, which generate audible noises
when the operating frequency is in the range of
20~20,000Hz. Even though they operate above 20KHz,
they can make noise depending on the load condition.
Here are three methods to reduce noise:
Glue or Varnish
The most common method involves using glue or
varnish to tighten magnetic components. The motion of
core, bobbin, and coil and the chattering or
magnetostriction of core can cause the transformer to
produce audible noise. The use of rigid glue and varnish
helps reduce the transformer noise. Glue or varnish can
also can crack the core because sudden changes in the
ambient temperature cause the core and the glue to
expand or shrink in a different ratio according to the
temperature.
Ceramic Capacitor
Using a film capacitor instead of a ceramic capacitor as a
snubber capacitor is another noise reduction solution.
Some dielectric materials show a piezoelectric effect
depending on the electric field intensity. Hence, a
snubber capacitor becomes one of the most significant
sources of audible noise. Another consideration is to
use a zener clamp circuit instead of an RCD snubber for
higher efficiency as well as lower audible noise.
Adjusting Sound Frequency
Moving the fundamental frequency of noise out of
2~4KHz range is the third method. Generally, humans
are more sensitive to noise in the range of 2~4KHz.
When the fundamental frequency of noise is located in
this range, the noise sounds louder although the noise
intensity level is identical. Refer to Figure 11.
When FPS acts in Burst mode and the Burst operation is
suspected to be a source of noise, this method may be
helpful. If the frequency of Burst mode operation lies in
the range of 2~4KHz, adjusting the feedback loop can
shift the Burst operation frequency. In order to reduce
the Burst operation frequency, increase a feedback gain
capacitor (C
F
), optocoupler supply resistor (R
D
) and
feedback capacitor (C
B
) and decrease a feedback gain
resistor (R
F
) as shown in Figure 12.
Figure 11. Equal Loudness Curves
Figure 12. Typical Feedback Network of FPS
2. Other Reference Materials
AN-4134
: Design Guidelines for Off-line Forward
Converters Using Fairchild Power Switch (FPS)
AN-4137
:Design Guidelines for Off-line Flyback
Converters Using Fairchild Power Switch (FPS)
AN-4140
: Transformer Design Consideration for Off-line
Flyback Converters using Fairchild Power Switch (FPS)
AN-4141
: Troubleshooting and Design Tips for Fairchild
Power Switch (FPS) Flyback Applications
AN-4147
: Design Guidelines for RCD Snubber of
Flyback
AN-4148
: Audible Noise Reduction Techniques for FPS
Applications
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| FSDH0265RL | Green Mode Fairchild Power Switch (FPSTM) |
| FSDH0265RN | Green Mode Fairchild Power Switch (FPSTM) |
| FSDH321 | Green Mode Fairchild Power Switch (FPSTM) |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| FSDH0370RNB | 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 |
| FSDH0565 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch (FPSTM) |
| FSDH321 | 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 |
| FSDH321_04 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Green Mode Fairchild Power Switch |
| FSDH321L | 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 |
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