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參數(shù)資料
| 型號： | ML4875 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | High Current Boost Regulator with Shutdown(帶關(guān)斷電路的大電流升壓穩(wěn)壓器) |
| 中文描述： | 高電流升壓關(guān)斷穩(wěn)壓器（帶關(guān)斷電路的大電流升壓穩(wěn)壓器） |
| 文件頁數(shù)： | 6/10頁 |
| 文件大?。?/td> | 188K |
| 代理商： | ML4875 |
6
ML4875
1.0
3.0
I
O
2.0
400
300
200
100
00
V
IN
(V)
ML4875-3.3
4.0
5.0
L = 27μH
L = 15μH
L = 56μH
1.0
3.0
I
O
2.0
400
300
200
100
00
V
IN
(V)
ML4875-5.0
4.0
5.0
L = 27μH
L = 15μH
L = 56μH
In the two cell application previously described, a
maximum input voltage of 3V would give a peak current
of 1.2A. When comparing various inductors, it is
important to keep in mind that suppliers use different
criteria to determine their ratings. Many use a
conservative current level, where inductance has dropped
to 90% of its normal level. In any case, it is a good idea to
try inductors of various current ratings with the ML4875 to
determine which inductor is the best choice. Check
efficiency and maximum output current, and if a current
probe is available, look at the inductor current to see if it
looks like the waveform shown in Figure 3. For additional
information, see Applications Note 29.
Suitable inductors can be purchased from the following
suppliers:
Coilcraft
(708) 639-6400
Coiltronics
(407) 241-7876
Dale
(605) 665-9301
Sumida
(708) 956-0666
tolerances. Assuming that 2V is the end of life voltage of a
two cell input, Figure 4 shows that with a 2V input, the
ML4875-5 delivers 99mA with a 27μH inductor.
Figure 5 shows efficiency under the conditions used to
create Figure 4. It can be seen that efficiency is mostly
independent of input voltage and is closely related to
inductor value. This illustrates the need to keep the
inductor value as high as possible to attain peak system
efficiency. As the inductor value goes down to 15μH, the
efficiency drops to between 70% and 75%. With 56μH,
the efficiency approaches 90% and there is little room for
improvement. At values greater than 100μH, the operation
of the synchronous rectifier becomes unreliable because
the inductor current is so small that it is difficult for the
control circuitry to detect. The data used to generate
Figures 4 and 5 is provided in Table 1.
After the appropriate inductor value is chosen, it is
necessary to find the minimum inductor current rating
required. Peak inductor current is determined from the
following formula:
I
T
V
L
L PEAK
(
ON MAX
(
IN MAX
(
MIN
)
)
)
=
×
(3)
Figure 4. Output Current vs Input Voltage.
1.0
3.0
I
O
2.0
400
300
200
100
00
V
IN
(V)
ML4875-3.0
4.0
L = 27μH
L = 15μH
L = 56μH
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ML4875CS-3 | 制造商:Rochester Electronics LLC 功能描述: |
| ML4875CS-5 | 制造商:Rochester Electronics LLC 功能描述: |
| ML4875CS-T | 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel |
| ML4875ES-3 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Low Voltage Boost Regulator with Shutdown |
| ML4875ES-5 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:Low Voltage Boost Regulator with Shutdown |
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