- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄382828 > AAT1123IJS-1.2-T1 (Advanced Analog Technology,lnc.) 1MHz Step-Down Converter PDF資料下載
參數(shù)資料
| 型號： | AAT1123IJS-1.2-T1 |
| 廠商： | Advanced Analog Technology,lnc. |
| 英文描述： | 1MHz Step-Down Converter |
| 中文描述： | 1MHz的降壓轉(zhuǎn)換器 |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 568K |
| 代理商： | AAT1123IJS-1.2-T1 |
A laboratory test set-up typically consists of two
long wires running from the bench power supply to
the evaluation board input voltage pins. The induc-
tance of these wires, along with the low-ESR
ceramic input capacitor, can create a high Q net-
work that may affect converter performance. This
problem often becomes apparent in the form of
excessive ringing in the output voltage during load
transients. Errors in the loop phase and gain
measurements can also result.
Since the inductance of a short PCB trace feeding
the input voltage is significantly lower than the
power leads from the bench power supply, most
applications do not exhibit this problem.
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.
This dampens the high Q network and stabilizes
the system.
Output Capacitor
The output capacitor limits the output ripple and
provides holdup during large load transitions. A
22μF X5R or X7R ceramic capacitor provides suffi-
cient bulk capacitance to stabilize the output during
large load transitions 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 limits the
minimum output capacitor value to 22μF. 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 Resistor Selection
For applications requiring an adjustable output volt-
age, the 0.6V version can be externally pro-
grammed. Resistors R1 and R2 of Figure 5 program
the output to regulate at a voltage higher than 0.6V.
To limit the bias current required for the external
feedback resistor string while maintaining good
noise immunity, the minimum suggested value for
R2 is 59k
Ω
. Although a larger value will further
reduce quiescent current, it will also increase the
impedance of the feedback node, making it more
sensitive to external noise and interference. Table 2
summarizes the resistor values for various output
voltages with R2 set to either 59k
Ω
for good noise
immunity or 221k
Ω
for reduced no load input current.
The adjustable version of the AAT1123, combined
with an external feedforward capacitor (C4 in
Figure 1), delivers enhanced transient response for
extreme pulsed load applications. The addition of
the feedforward capacitor typically requires a larg-
er output capacitor C1 for stability.
R1 = V
·
R2 = 0.6V
·
59k
Ω
= 88.5k
Ω
REF
V
OUT
1.5V
1
2
3
V
OUT
· (V
IN(MAX)
- V
OUT
)
L
·
F
·
V
IN(MAX)
RMS(MAX)
I
=
·
·
C
OUT
=
3
·
Δ
I
LOAD
V
DROOP
·
F
S
AAT1123
1MHz Step-Down Converter
12
1123.2007.02.1.6
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AAT1142 | 800mA Voltage-Scaling Step-Down Converter |
| AAT1142ITP-1.8-T1 | 800mA Voltage-Scaling Step-Down Converter |
| AAT1142IWP-1.8-T1 | 800mA Voltage-Scaling Step-Down Converter |
| AAT1147 | High Efficiency, Low Noise, Fast Transient 400mA Step-Down Converter |
| AAT1147IJS-0.6-T1 | High Efficiency, Low Noise, Fast Transient 400mA Step-Down Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AAT1125IJS-0.6-T1 | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 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 |
| AAT1126 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:600mA, 1MHz Step-Down Converter |
| AAT1126IGV-0.6-T1 | 制造商:Skyworks Solutions Inc 功能描述:SKYAAT1126IGV-0.6-T1 DC/DC CONVERTERS (S 制造商:Skyworks Solutions Inc 功能描述:DC TO DC CONVERTER |
| AAT1130 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:2.5MHz 500mA Step-Down DC/DC Converter |
| AAT1130IJQ-0.6 | 制造商:ANALOGICTECH 制造商全稱:Advanced Analogic Technologies 功能描述:2.5MHz 500mA Step-Down DC/DC Converter |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。