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| 型号： | LT1110CS8-12#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 7/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BOOST 12V 0.4A 8SOIC |
| 标准包装： | 2,500 |
| 类型： | 降压（降压），升压（升压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 12V |
| 输入电压： | 1 V ~ 30 V |
| 频率 - 开关： | 70kHz |
| 电流 - 输出： | 400mA |
| 同步整流器： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-SOIC |
LT1110
A PPLICATI
S I FOR ATIO
Inductor Selection — General
Energy required by the inductor per cycle must be equal or
A DC-DC converter operates by storing energy as mag-
netic flux in an inductor core, and then switching this
energy into the load. Since it is flux, not charge, that is
greater than
P L
f OSC
( 02 )
stored, the output voltage can be higher, lower, or oppo-
site in polarity to the input voltage by choosing an appro-
priate switching topology. To operate as an efficient en-
ergy transfer element, the inductor must fulfill three re-
in order for the converter to regulate the output.
When the switch is closed, current in the inductor builds
according to
I L ( t ) = IN ? 1 – e L ?
quirements. First, the inductance must be low enough for
the inductor to store adequate energy under the worst
case condition of minimum input voltage and switch ON
V ? –R't ?
R ' ? ?
( 03 )
()
I L t = IN t
time. The inductance must also be high enough so maxi-
mum current ratings of the LT1110 and inductor are not
exceeded at the other worst case condition of maximum
input voltage and ON time. Additionally, the inductor core
must be able to store the required flux; i.e., it must not
saturate. At power levels generally encountered with
LT1110 based designs, small surface mount ferrite core
units with saturation current ratings in the 300mA to 1A
range and DCR less than 0.4 ? (depending on application)
are adequate. Lastly, the inductor must have sufficiently
low DC resistance so excessive power is not lost as heat
in the windings. An additional consideration is Electro-
Magnetic Interference (EMI). Toroid and pot core type
inductors are recommended in applications where EMI
where R' is the sum of the switch equivalent resistance
(0.8 ? typical at 25 ° C) and the inductor DC resistance.
When the drop across the switch is small compared to V IN ,
the simple lossless equation
V
( 04 )
L
can be used. These equations assume that at t = 0,
inductor current is zero. This situation is called “discon-
tinuous mode operation” in switching regulator parlance.
Setting “t” to the switch ON time from the LT1110 speci-
fication table (typically 10 μ s) will yield I PEAK for a specific
“L” and V IN . Once I PEAK is known, energy in the inductor
at the end of the switch ON time can be calculated as
1 2
2 PEAK
must be kept to a minimum; for example, where there are
sensitive analog circuitry or transducers nearby. Rod core
types are a less expensive choice where EMI is not a
E L =
LI
( 05 )
problem. Minimum and maximum input voltage, output
voltage and output current must be established before an
inductor can be selected.
Inductor Selection — Step-Up Converter
In a step-up, or boost converter (Figure 4), power gener-
ated by the inductor makes up the difference between
input and output. Power required from the inductor is
determined by
E L must be greater than P L /f OSC for the converter to deliver
the required power. For best efficiency I PEAK should be
kept to 1A or less. Higher switch currents will cause
excessive drop across the switch resulting in reduced
efficiency. In general, switch current should be held to as
low a value as possible in order to keep switch, diode and
inductor losses at a minimum.
As an example, suppose 12V at 120mA is to be generated
from a 4.5V to 8V input. Recalling equation (01),
P L = ( V OUT + V D – V IN MIN )( I OUT
)
( 01 )
P L = ( 12 V + 0 . 5 V – 4 . 5 V )( 120 mA ) = 960 mW . ( 06 )
where V D is the diode drop (0.5V for a 1N5818 Schottky).
Energy required from the inductor is
= = 13 . 7 μ J .
P L
f OSC
960mW
70 kHz
( 07 )
7
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相关代理商/技术参数 |
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| LT1110CS8-5 | 功能描述:IC REG BUCK BOOST 5V 0.4A 8SOIC 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 |
| LT1110CS8-5#PBF | 功能描述:IC REG BUCK BOOST 5V 0.4A 8SOIC 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 |
| LT1110CS8-5#TR | 功能描述:IC REG BUCK BOOST 5V 0.4A 8SOIC 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 |
| LT1110CS8PBF | 制造商:Linear Technology 功能描述:DC-DC Converter Step-Up/Down 1-30V SOIC8 |
| LT1111 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower DC/DC Converter Adjustable and Fixed 5V, 12V |
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