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参数资料
| 型号： | LT3508IUF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 3.2 A DUAL SWITCHING CONTROLLER, 1060 kHz SWITCHING FREQ-MAX, PQCC24 |
| 封装： | 4 X 4 MM, PLASTIC, MO-220WGGD-X, QFN-24 |
| 文件页数： | 2/24页 |
| 文件大小： | 365K |
| 代理商： | LT3508IUF |
LT3508
10
3508f
Choosing a high switching frequency will allow the smallest
overall solution size. However, at high input voltages the
efciency can drop signicantly with increasing switching
frequency. The choice of switching frequency will also
impact the input voltage range, inductor and capacitor
selection, and compensation. See the related sections
for details.
Inductor Selection and Maximum Output Current
A good rst choice for the inductor value is:
LV
V
MHz
f
OUT
F
=+
()
.
12
where VFisthevoltagedropofthecatchdiode(~0.4V)andL
is in μH. The inductor’s RMS current rating must be greater
than the maximum load current and its saturation current
should be at least 30% higher. For highest efciency, the
series resistance (DCR) should be less than 0.1
Ω. Table 2
lists several vendors and types that are suitable.
Table 2. Inductor Vendors
VENDOR
URL
PART SERIES
TYPE
Coilcraft
www.coilcraft
MSS7341
Shielded
Murata
www.murata.com
LQH55D
Open
TDK
www.component.tdk.com
SLF7045
SLF10145
Shielded
Toko
www.toko.com
DC62CB
D63CB
D75C
D75F
Shielded
Open
Sumida
www.sumida.com
CR54
CDRH74
CDRH6D38
CR75
Open
Shielded
Open
The optimum inductor for a given application may differ
from the one indicated by this simple design guide. A larger
value inductor provides a higher maximum load current,
and reduces the output voltage ripple. If your load is lower
than the maximum load current, then you can relax the
value of the inductor and operate with higher ripple cur-
rent. This allows you to use a physically smaller inductor,
or one with a lower DCR resulting in higher efciency.
Be aware that if the inductance differs from the simple
Figure 2. Operation Below VIN(PS). VIN = 10V, VOUT = 1.8V and
fSW = 1.5MHz
Figure 3. Operation Above VIN(PS). VIN = 18V, VOUT = 1.8V
and fSW = 1.5MHz. Output Ripple and Peak Inductor Current
Increase
APPLICATIONS INFORMATION
VOUT
100mV/DIV
(AC)
IL
500mA/DIV
2
s/DIV
3508 F02
VOUT
100mV/DIV
(AC)
IL
500mA/DIV
2
s/DIV
3508 F03
Setting the Switching Frequency
The switching frequency is programmed either by driving
the RT/SYNC pin with a logic level SYNC signal or by tying
a resistor from the RT/SYNC pin to ground. A graph for
selecting the value of RT for a given operating frequency
is shown in the Typical Application section. Suggested
programming resistors for various switching frequencies
are shown in Table 1.
Table 1. Programming the Switching Frequency
SWITCHING FREQUENCY (MHz)
RT (kΩ)
2.5
7.50
2
11.5
1.4
20.5
1
33.2
0.7
52.3
0.5
76.8
0.35
115
0.25
169
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相关代理商/技术参数 |
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| LT3508IUF#PBF | 功能描述:IC REG BUCK ADJ 1.4A DL 24QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LT3508IUF#PBF | 制造商:Linear Technology 功能描述:DC-DC CONVERTER BUCK 1MHZ Q 制造商:Linear Technology 功能描述:DC-DC CONVERTER, BUCK, 1MHZ, QFN-24 |
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| LT3508IUF-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Monolithic 1.4A Step-Down Switching Regulator |
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