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参数资料
| 型号： | LTC1474IS8-5#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.75 A SWITCHING REGULATOR, PDSO8 |
| 封装： | 0.150 INCH, PLASTIC, SO-8 |
| 文件页数： | 5/20页 |
| 文件大小： | 237K |
| 代理商： | LTC1474IS8-5#TR |
13
LTC1474/LTC1475
APPLICATIONS INFORMATION
WU
U
Figure 9. LTC1474/LTC1475 Layout Diagram (See Board Layout Checklist)
+
VOUT
VIN
RSENSE
VFB
COUT
CIN
10pF
1000pF
R2
100k
LTC1474
R1
D1
LBO
LBI
GND
RUN
SENSE
SW
L
1474/75 F09
8
7
6
5
1
2
3
4
BOLD LINES INDICATE HIGH PATH CURRENTS
0.1
F
OUTPUT DIVIDER REQUIRED WITH
ADJUSTABLE VERSION ONLY
5. Are the signal and power grounds segregated? The
signal ground consists of the (–) plate of COUT, Pin 4 of
the LTC1474/LTC1475 and the resistive divider. The
power ground consists of the Schottky diode anode,
the (–) plate of CIN and the 0.1F decoupling capacitor.
6. Is a 100k resistor connected in series between RUN
(Pin 8) and the RUN control voltage? The resistor
should be as close as possible to Pin 8.
Design Example (Refer to RSENSE and Inductor
Selection)
As a design example, assume VIN = 10V, VOUT = 3V, and
a maximum average output current IMAX = 100mA. With
this information, we can easily calculate all the important
components:
From the equation (1),
RSENSE = (0.067/0.1) – 0.25 = 0.42
Using the standard resistors (1
, 1 and 2) in parallel
provides 0.4
without having to use a more expensive
low value current shunt type resistor (see RSENSE Selec-
tion section).
With RSENSE = 0.4, the peak inductor current IPEAK is
calculated from (2), neglecting the second term, to be
150mA. The minimum inductance is, therefore, from the
equation (3) and assuming VD = 0.4V,
L
s
H
MIN =
+
()(
)
=
075 3 3 0 4 4 75
015 0 1
264
..
.
..
From Figure 3, an inductance of 270
H is chosen from the
recommended region. The CDRH73-271 or CD54-271 is a
good choice for space limited applications.
For the feedback resistors, choose R1 = 1M to minimize
supply current. R2 can then be calculated from the equa-
tion (4) to be:
R
V
RM
OUT
2
123
11 1 43
=
=
.
For the catch diode, the MBR0530 will work well in this
application.
For the input and output capacitors, AVX 4.7
F and 100F,
respectively, low ESR TPS series work well and meet the
RMS current requirement of 100mA/2 = 50mA. They are
available in small “C” case sizes with 0.15
ESR. The
0.15
output capacitor ESR will result in 25mV of output
voltage ripple.
Figure 10 shows the complete circuit for this example.
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相关代理商/技术参数 |
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| LTC1475CMS8 | 功能描述:IC REG BUCK ADJ 0.75A 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 |
| LTC1475CMS8#PBF | 功能描述:IC REG BUCK ADJ 0.75A 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: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 |
| LTC1475CMS8#TR | 功能描述:IC REG BUCK ADJ 0.75A 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 |
| LTC1475CMS8#TRPBF | 功能描述:IC REG BUCK ADJ 0.75A 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: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 |
| LTC1475CMS8-3.3 | 功能描述:IC REG BUCK 3.3V 0.75A 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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