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參數(shù)資料
| 型號： | AAT2550ISK-CAA-T1 |
| 廠商： | Advanced Analog Technology,lnc. |
| 英文描述： | Total Power Solution for Portable Applications |
| 中文描述： | 總功率便攜式應(yīng)用解決方案 |
| 文件頁數(shù)： | 23/35頁 |
| 文件大?。?/td> | 914K |
| 代理商： | AAT2550ISK-CAA-T1 |
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Step-Down Converter
Applications Information
Inductor Selection
The step-down converter uses peak current mode
control with slope compensation to maintain stability
for duty cycles greater than 50%. The output induc-
tor value must be selected so the inductor current
down slope meets the internal slope compensation
requirements. The internal slope compensation for
the adjustable and low-voltage fixed versions of the
AAT2550 is 0.24A/μsec. This equates to a slope
compensation that is 75% of the inductor current
down slope for a 1.5V output and 4.7μH inductor.
This is the internal slope compensation for the
adjustable (0.6V) version or low-voltage fixed ver-
sions. When externally programming the 0.6V ver-
sion to 2.5V, the calculated inductance is 7.5μH.
In this case, a standard 6.8μH value is selected.
For high-voltage fixed versions (
≥
2.5V), m = 0.48A/
μsec. Table 5 displays inductor values for the
AAT2550 fixed and adjustable options.
Manufacturer's specifications list both the inductor
DC current rating, which is a thermal limitation, and
the peak current rating, which is determined by the
saturation characteristics. The inductor should not
show any appreciable saturation under normal load
conditions. Some inductors may meet the peak and
average current ratings yet result in excessive loss-
es due to a high DCR. Always consider the losses
associated with the DCR and its effect on the total
converter efficiency when selecting an inductor.
The Sumida 4.7μH CDRH3D16 series inductor has
a 105m
Ω
DCR and a 900mA DC current rating. At
full load, the inductor DC loss is 38mW, which gives
a 4% loss in efficiency for a 600mA, 1.5V output.
Input Capacitor
Select a 4.7μF to 10μF X7R or X5R ceramic capac-
itor for the input. To estimate the required input
capacitor size, determine the acceptable input rip-
ple level (V
PP
) and solve for C. The calculated
value varies with input voltage and is a maximum
when V
IN
is double the output voltage.
Always examine the ceramic capacitor DC voltage
coefficient characteristics when selecting the prop-
er value. For example, the capacitance of a 10μF,
6.3V, X5R ceramic capacitor with 5.0V DC applied
is actually about 6μF.
C
IN(MIN)
=
1
- ESR
·
4
·
F
S
I
O
V
PP
· 1
-
= 1
IN
= 2 · V
O
V
IN
V
IN
O
V
O
4
· 1
-
V
O
V
IN
C
IN
=
V
O
V
IN
- ESR
·
F
S
V
PP
I
O
0.75
V
L = m
≈
3 A
V
O
0.24A
= 3 A
2.5V = 7.5
μ
H
0.75
V
O
sec
μ
sec
A
μ
sec
0.75
V
m = L
0.75
1.5V
4.7
μ
H
A
μ
sec
AAT2550
Total Power Solution for Portable Applications
2550.2006.07.1.0
23
Table 5: Inductor Values.
Configuration
Output Voltage
Inductor
0.6V Adjustable With
External Feedback
1V, 1.2V
1.5V, 1.8V
2.5V, 3.3V
0.6V to 3.3V
2.2μH
4.7μH
6.8μH
4.7μH
Fixed Output
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| AAT2550 | Total Power Solution for Portable Applications |
| AAT2554 | Total Power Solution for Portable Applications |
| AAT2554IRN-CAP-T1 | Total Power Solution for Portable Applications |
| AAT2554IRN-CAQ-T1 | Total Power Solution for Portable Applications |
| AAT2554IRN-CAT-T1 | Total Power Solution for Portable Applications |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AAT2552 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:Total Power Solution for Portable Applications |
| AAT2552_08 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:Total Power Solution for Portable Applications |
| AAT2552IRN-CAE-T1 | 功能描述:電荷泵 Total Pwr Solution for Portable App RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| AAT2554 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:Total Power Solution for Portable Applications |
| AAT2554IRN-CAP-T1 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:Total Power Solution for Portable Applications |
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