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參數(shù)資料
| 型號： | LT3724EFE |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| 中文描述： | 0.3 A SWITCHING CONTROLLER, 220 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 4.4 MM, PLASTIC, TSSOP-16 |
| 文件頁數(shù)： | 12/24頁 |
| 文件大?。?/td> | 240K |
| 代理商： | LT3724EFE |
LT3724
12
3724f
The basic LT3724 step-down (buck) application, shown in
the Typical Application on the front page, converts a larger
positive input voltage to a lower positive or negative
output voltage. This Application Information section as-
sists selection of external components for the require-
ments of the power supply.
R
SENSE
Selection
The current sense resistor, R
SENSE
, monitors the inductor
current of the supply (See Typical Application on front
page). Its value is chosen based on the maximum required
output load current. The LT3724 current sense amplifier
has a maximum voltage threshold of, typically, 150mV.
Therefore, the peak inductor current is 150mV/R
SENSE
.
The maximum output load current, I
OUT(MAX)
, is the peak
inductor current minus half the peak-to-peak ripple cur-
rent,
I
L
.
Allowing adequate margin for ripple current and external
component tolerances, R
SENSE
can be calculated as
follows:
mV
I
OUT MAX
(
)
R
SENSE
=
100
Typical values for R
SENSE
are in the range of 0.005
to 0.05
.
Inductor Selection
The critical parameters for selection of an inductor are
minimum inductance value, volt-second product, satura-
tion current and/or RMS current.
The minimum inductance value is calculated as follows:
L
V
V
V
f
V
I
OUT
IN MAX
OUT
)
SW
IN MAX
(
L
≥
–
(
)
f
SW
is the switch frequency (200kHz).
The typical range of values for
I
L
is (0.2 I
OUT(MAX)
) to
(0.5 I
OUT(MAX)
), where I
OUT(MAX)
is the maximum load
current of the supply. Using
I
L
= 0.3 I
OUT(MAX)
yields a
good design compromise between inductor performance
versus inductor size and cost. Higher values of
I
L
will
increase the peak currents, requiring more filtering on the
input and output of the supply. If
I
L
is too high, the slope
compensation circuit is ineffective and current mode
instability may occur at duty cycles greater than 50%.
Lower values of
I
L
require larger and more costly mag-
netics. A value of
I
L
= 0.3 I
OUT(MAX)
produces a
±
15%
of I
OUT(MAX)
ripple current around the DC output current of
the supply.
Some magnetics vendors specify a volt-second product in
their datasheet. If they do not, consult the magnetics
vendor to make sure the specification is not being ex-
ceeded by your design. The volt-second product is calcu-
lated as follows:
Volt-second (
μ
sec) =
(
–
)
(
)
(
)
V
V
V
V
f
IN MAX
OUT
OUT
IN MAX
SW
The magnetics vendors specify either the saturation cur-
rent, the RMS current or both. When selecting an inductor
based on inductor saturation current, use the peak current
through the inductor, I
OUT(MAX)
+
I
L
/2. The inductor
saturation current specification is the current at which the
inductance, measured at zero current, decreases by a
specified amount, typically 30%.
When selecting an inductor based on RMS current rating,
use the average current through the inductor, I
OUT(MAX)
.
The RMS current specification is the RMS current at which
the part has a specific temperature rise, typically 40
°
C,
above 25
°
C ambient.
After calculating the minimum inductance value, the volt-
second product, the saturation current and the RMS
current for your design, select an off-the-shelf inductor. A
list of magnetics vendors can be found at www.linear.com,
or contact the Linear Technology Application Department.
For more detailed information on selecting an inductor,
please see the “Inductor Selection” section of Linear
Technology Application Note 44.
Step-Down Converter: MOSFET Selection
The selection criteria of the external N-channel standard
level power MOSFET include on resistance(R
DS(ON)
), re-
verse transfer capacitance (C
RSS
), maximum drain source
voltage (V
DSS
), total gate charge (Q
G
), and maximum
continuous drain current.
APPLICATIOU
W
U
U
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| LT3724EFE#PBF | 功能描述:IC REG CTRLR BST INV PWM 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LT3724EFE#TRPBF | 功能描述:IC REG CTRLR BST INV PWM 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LT3724EFEPBF | 制造商:Linear Technology 功能描述:60V Current-Mode Controller TSSOP16EP |
| LT3724EFE-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Voltage, Current Mode Switching Regulator Controller |
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