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参数资料
| 型号： | LT1767EMS8E-3.3 |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| 中文描述： | 3 A SWITCHING REGULATOR, 1500 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | PLASTIC, MSOP-8 |
| 文件页数： | 9/16页 |
| 文件大小： | 242K |
| 代理商： | LT1767EMS8E-3.3 |
9
LT1767/LT1767-1.8/
LT1767-2.5/LT1767-3.3/LT1767-5
sn1767 1767fas
APPLICATIO
S I
N
FOR
ATIO
U
saturation of the inductor. In these applications, the
soft-start circuit shown in Figure 10 should be used.
2. Calculate peak inductor current at full load current to
ensure that the inductor will not saturate. Peak current
can be significantly higher than output current,
especially with smaller inductors and lighter loads, so
don’t omit this step. Powdered iron cores are forgiving
because they saturate softly, whereas ferrite cores
saturate abruptly. Other core materials fall somewhere
in between.
(
( )( )( )
W
U
4. After making an initial choice, consider the secondary
things like output voltage ripple, second sourcing, etc.
Use the experts in the Linear Technology’s applica-
tions department if you feel uncertain about the final
choice. They have experience with a wide range of
inductor types and can tell you about the latest devel-
opments in low profile, surface mounting, etc.
CATCH DIODE
The suggested catch diode (D1) is a UPS120 Schottky, or
its Motorola equivalent, MBRM120LTI/MBRM130LTI. It
is rated at 2A average forward current and 20V/30V
reverse voltage. Typical forward voltage is 0.5V at 1A. The
diode conducts current only during switch off time. Peak
reverse voltage is equal to regulator input voltage. Average
forward current in normal operation can be calculated
from:
(
I
I
V
V
V
D AVG
OUT
IN
OUT
IN
)
=
)
BOOSTPIN
For most applications, the boost components are a 0.1
μ
F
capacitor and a CMDSH-3 diode. The anode is typically
connected to the regulated output voltage to generate a
voltage approximately V
OUT
above V
IN
to drive the output
stage. The output driver requires at least 2.7V of head-
room throughout the on period to keep the switch fully
saturated. However, the output stage discharges the boost
capacitor during the on time. If the output voltage is less
than 3.3V, it is recommended that an alternate boost
supply is used. The boost diode can be connected to the
input, although, care must be taken to prevent the 2x V
IN
boost voltage from exceeding the BOOST pin absolute
maximum rating. The additional voltage across the switch
driver also increases power loss, reducing efficiency. If
available, an independent supply can be used with a local
bypass capacitor.
A 0.1
μ
F boost capacitor is recommended for most appli-
cations. Almost any type of film or ceramic capacitor is
I
I
V
V
V
L f V
PEAK
OUT
OUT
2
IN
OUT
IN
=
+
)
V
IN
= Maximum input voltage
f = Switching frequency, 1.25MHz
3. Decide if the design can tolerate an “open” core geom-
etry like a rod or barrel, which have high magnetic field
radiation, or whether it needs a closed core like a toroid
to prevent EMI problems. This is a tough decision
because the rods or barrels are temptingly cheap and
small and there are no helpful guidelines to calculate
when the magnetic field radiation will be a problem.
Table 3
PART NUMBER
Coiltronics
TP1-2R2
TP2-2R2
TP3-4R7
TP4- 100
Murata
LQH1C1R0M04
LQH3C1R0M24
LQH3C2R2M24
LQH4C1R5M04
Sumida
CD73- 100
CDRH4D18-2R2
CDRH5D18-6R2
CDRH5D28-100
VALUE (uH)
I
SAT
(Amps)
DCR (
)
HEIGHT (mm)
2.2
2.2
4.7
10
1.3
1.5
1.5
1.5
0.188
0.111
0.181
0.146
1.8
2.2
2.2
3.0
1.0
1.0
2.2
1.5
0.51
1.0
0.79
1.0
0.28
0.06
0.1
0.09
1.8
2.0
2.0
2.6
10
2.2
6.2
10
1.44
1.32
1.4
1.3
0.080
0.058
0.071
0.048
3.5
1.8
1.8
2.8
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| LT1767EMS8E-5 | 功能描述:IC REG BUCK 5V 1.5A 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT1767EMS8E-5#PBF | 功能描述:IC REG BUCK 5V 1.5A 8MSOP 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 |
| LT1767EMS8E-5#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC 制造商:Linear Technology 功能描述:IC, STEP-DOWN REGULATOR, MSOP-8 |
| LT1767EMS8E-5#TR | 功能描述:IC REG BUCK 5V 1.5A 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
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