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參數(shù)資料
| 型號： | MP1517 |
| 廠商： | Monolithic Power Systems, Inc. |
| 英文描述： | 3A, 25V, 1.1MHz Step-Up Converter |
| 中文描述： | 第3A，25V的，為1.1MHz升壓轉(zhuǎn)換器 |
| 文件頁數(shù)： | 6/13頁 |
| 文件大?。?/td> | 323K |
| 代理商： | MP1517 |
MP1517 – 3A, 25V, 1.1MHz STEP-UP CONVERTER
MP1517 Rev. 1.4
4/28/2006
www.MonolithicPower.com
6
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
2006 MPS. All Rights Reserved.
Internal Low-Dropout Regulator
The internal power to the MP1517 is supplied
from the IN pin through an internal 2.4V low-
dropout linear regulator, whose output is BP.
Bypass BP to SGND with a 10nF or greater
capacitor to insure the MP1517 operates
properly. The internal regulator can not supply
any more current than is required to operate the
MP1517, therefore do not apply any external
load to BP.
Soft-Start
The MP1517 includes a soft-start timer that limits
the voltage at COMP during startup to prevent
excessive current at the input. This prevents
premature termination of the source voltage at
startup due to input current overshoot. When
power is applied to the MP1517, and enable is
asserted, a 2μA internal current source charges
the external capacitor at SS. As the capacitor
charges, the voltage at SS rises. The MP1517
internally clamps the voltage at COMP to 700mV
above the voltage at SS. This limits the inductor
current at startup, forcing the input current to rise
slowly to the current required to regulate the
output voltage.
Open Load Shutdown
The MP1517 includes an open load detect that
will stop the output from switching. In a fault
condition where the connection to the LED’s is
open, V
OUT
will rise up. Once V
OUT
exceeds
27V, the MP1517 will stop switching and the
output will stop rising. When the output falls
below 27V the MP1517 will restart in soft-start
mode and switches until the OLS threshold is
exceeded again. This will continue until the part
is disabled. To disable the open load shutdown
feature, connect the OLS pin to GND.
APPLICATION INFORMATION
GENERAL PURPOSE COMPONENT
SELECTION
Setting the Output Voltage
Set the output voltage by selecting the resistive
voltage divider ratio. Use 10k
to 50k
for the
low-side resistor R2 of the voltage divider.
Determine the high-side resistor R1 by the
equation:
(
V
2
R
1
R
=
)
FB
FB
OUT
V
V
×
where V
OUT
is the output voltage.
For R2 = 10k
and V
FB
= 0.7V, then
R1 (k
) = 14.29k
(V
OUT
– 0.7V).
Selecting the Inductor
The inductor is required to force the higher
output voltage while being driven by the input
voltage. A larger value inductor results in less
ripple current, resulting in lower peak inductor
current and reducing stress on the internal
N-Channel
.
MOSFET switch. However, the
larger value inductor has a larger physical size,
higher
series
resistance,
saturation current.
and/or
lower
Choose an inductor that does not saturate
under the worst-case load transient and startup
conditions. A good rule for determining the
inductance is to allow the peak-to-peak ripple
current to be approximately 30% to 50% of the
maximum input current. Make sure that the
peak inductor current is below 3A to prevent
loss of regulation due to the current limit.
Calculate the required inductance value by the
equation:
I
f
V
)
V
×
-
(V
V
L
SW
OUT
IN
OUT
×
IN
×
=
η
×
×
=
IN
)
MAX
(
LOAD
I
OUT
V
)
MAX
(
IN
I
V
(
)
)
MAX
(
IN
I
%
50
%
30
I
×
=
Where V
IN
is the input voltage,
switching frequency, I
LOAD(MAX)
is the maximum
load current,
I is the peak-to-peak inductor ripple
current and
η
is the efficiency.
SW
f
is the
Selecting the Input Capacitor
An input capacitor is required to supply the AC
ripple current to the inductor, while limiting
noise at the input source. A low ESR capacitor
is required to keep the noise at the IC to a
minimum. Ceramic capacitors are preferred, but
tantalum or low-ESR electrolytic capacitors may
also suffice.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MP1517DR | 制造商:MPS 制造商全稱:Monolithic Power Systems 功能描述:3A, 25V, 1.1MHz Step-Up Converter |
| MP1517DR-LF-P | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 3A Switch / 25Vout Step-Up Converter 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 |
| MP1517DR-LF-Z | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 3A Switch / 25Vout Step-Up Converter 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 |
| MP1518 | 制造商:MPS 制造商全稱:Monolithic Power Systems 功能描述:Fixed Frequency White LED Driver |
| MP1518DG | 制造商:MPS 制造商全稱:Monolithic Power Systems 功能描述:Fixed Frequency White LED Driver |
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