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參數(shù)資料
| 型號： | AAT2500M |
| 廠商： | Advanced Analogic Technologies, Inc. |
| 英文描述： | 400mA Step-Down Converter and 300mA LDO |
| 中文描述： | 400mA的降壓轉(zhuǎn)換器和300mA的LDO |
| 文件頁數(shù)： | 15/22頁 |
| 文件大?。?/td> | 547K |
| 代理商： | AAT2500M |
AAT2500M
400mA Step-Down Converter and 300mA LDO
2500M.2007.06.1.0
15
In applications where the input power source lead
inductance cannot be reduced to a level that does
not affect the converter performance, a high ESR
tantalum or aluminum electrolytic should be placed
in parallel with the low ESR, ESL bypass ceramic
capacitor. This dampens the high Q network and
stabilizes the system.
Output Capacitor
The step-down converter output capacitor limits the
output ripple and provides holdup during large load
transitions. A 4.7μF to 10μF X5R or X7R ceramic
capacitor typically provides sufficient bulk capaci-
tance to stabilize the output during large load tran-
sitions and has the ESR and ESL characteristics
necessary for low output ripple.
The output voltage droop due to a load transient is
dominated by the capacitance of the ceramic out-
put capacitor. During a step increase in load cur-
rent, the ceramic output capacitor alone supplies
the load current until the loop responds. Within two
or three switching cycles, the loop responds and
the inductor current increases to match the load
current demand. The relationship of the output volt-
age droop during the three switching cycles to the
output capacitance can be estimated by:
Once the average inductor current increases to the
DC load level, the output voltage recovers. The
above equation establishes a limit on the minimum
value for the output capacitor with respect to load
transients.
The internal voltage loop compensation also limits
the minimum output capacitor value to 4.7μF. This
is due to its effect on the loop crossover frequency
(bandwidth), phase margin, and gain margin.
Increased output capacitance will reduce the
crossover frequency with greater phase margin.
The maximum output capacitor RMS ripple current
is given by:
Dissipation due to the RMS current in the ceramic
output capacitor ESR is typically minimal, resulting in
less than a few degrees rise in hot-spot temperature.
Adjustable Output Voltage Resistor
Selection
For applications requiring an adjustable output volt-
age (V
O
or V
OUT
), the 0.6V version can be externally
programmed. Resistors R1 and R2 of Figure 5 pro-
gram the output to regulate at a voltage higher than
0.6V. To limit the bias current required for the exter-
nal feedback resistor string while maintaining good
noise immunity, the minimum suggested value for R2
1
2
3
V
OUT
· (V
IN(MAX)
- V
OUT
)
L
·
F
OSC
·
V
IN(MAX)
RMS(MAX)
I
=
·
·
C
OUT
=
3
·
I
LOAD
V
DROOP
·
F
OSC
Figure 3: AAT2500M Evaluation Board Top Side.
Figure 4: AAT2500M Evaluation Board
Bottom Side.
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| AAT2500MITP-AW-T1 | 400mA Step-Down Converter and 300mA LDO |
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| AAT2500IFP-AQ-T1 | 1MHz Step-Down Converter/LDO Regulator |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AAT2500MITP-AW-T1 | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 400mA Step-Down Convrt + 300mA LDO 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 |
| AAT2503 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:Adjustable 3-Channel Regulator |
| AAT2503_08 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:Adjustable 3-Channel Regulator |
| AAT2503IZL-BAA-T1 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:Adjustable 3-Channel Regulator |
| AAT2504 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:Adjustable 3-Channel Regulator |
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