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参数资料
| 型号： | LT1371CT7 |
| 厂商： | Linear Technology |
| 文件页数： | 8/16页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG ADJ TO220-7 |
| 标准包装： | 50 |
| 类型： | 降压（降压），升压（升压），反相，Cuk，回扫，正向转换器 |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.25 V ~ 35 V |
| 输入电压： | 2.7 V ~ 25 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 500kHz |
| 电流 - 输出： | 3A |
| 同步整流器： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 通孔 |
| 封装/外壳： | TO-220-7 成形引线 |
| 包装： | 管件 |
| 供应商设备封装： | TO-220-7 |
LT1371
APPLICATIO S I FOR ATIO
Shutdown and Synchronization
The 7-pin R and T7 package devices have a dual function
S/S pin which is used for both shutdown and synchroni-
zation. The SW package device has both a Shutdown
(SHDN) pin and a Synchronization (SYNC) pin which can
be used separately or tied together. These pins are logic
level compatible and can be pulled high, tied to V IN or left
floating for normal operation. A logic low on the S/S pin or
SHDN pin activates shutdown, reducing the part’s supply
current to 12 μ A. Typical synchronization range is from
1.05 to 1.8 times the part’s natural switching frequency,
but is only guaranteed between 600kHz and 800kHz. A
12 μ s resetable shutdown delay network guarantees the
part will not go into shutdown while receiving a synchro-
nization signal when the functions are combined.
Caution should be used when synchronizing above 700kHz
because at higher sync frequencies the amplitude of the
internal slope compensation used to prevent subharmonic
switching is reduced. This type of subharmonic switching
only occurs when the duty cycle of the switch is above 50%.
Higher inductor values will tend to eliminate problems.
Thermal Considerations
Care should be taken to ensure that the worst-case input
voltage and load current conditions do not cause exces-
sive die temperatures. Typical thermal resistance is
30 ° C/W for the R package and 50 ° C/W for the SW and T7
packages but these numbers will vary depending on the
mounting techniques (copper area, air flow, etc.). Heat is
transferred from the R and T7 packages via the tab and
from the SW package via pins 4 to 7 and 14 to 17.
Average supply current (including driver current) is:
I IN = 4mA + DC [I SW /60 + I SW (0.004)]
I SW = switch current
DC = switch duty cycle
Switch power dissipation is given by:
P SW = (I SW ) 2 (R SW )(DC)
R SW = output switch ON resistance
8
Total power dissipation of the die is the sum of supply
current times supply voltage, plus switch power:
P D(TOTAL) = (I IN )(V IN ) + P SW
Surface mount heat sinks are also becoming available
which can lower package thermal resistance by 2 or 3
times. One manufacturer is Wakefield Engineering who
offers surface mount heat sinks for both the R package
(DD) and SW package (SW20) and can be reached at (617)
245-5900.
Choosing the Inductor
For most applications the inductor will fall in the range of
2.2 μ H to 22 μ H. Lower values are chosen to reduce physi-
cal size of the inductor. Higher values allow more output
current because they reduce peak current seen by the
power switch, which has a 3A limit. Higher values also
reduce input ripple voltage and reduce core loss.
When choosing an inductor you might have to consider
maximum load current, core and copper losses, allowable
component height, output voltage ripple, EMI, fault
current in the inductor, saturation and, of course, cost.
The following procedure is suggested as a way of handling
these somewhat complicated and conflicting requirements.
1. Assume that the average inductor current for a boost
converter is equal to load current times V OUT / V IN and
decide whether or not the inductor must withstand
continuous overload conditions. If average inductor
current at maximum load current is 1A, for instance, a
1A inductor may not survive a continuous 3A overload
condition. Also be aware that boost converters are not
short-circuit protected and that, under output short
conditions, inductor current is limited only by the
available current of the input supply.
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, espe-
cially with smaller inductors and lighter loads, so don’t
omit this step. Powdered iron cores are forgiving
because they saturate softly, whereas ferrite cores
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| LT1371CT7#PBF | 功能描述:IC REG MULTI CONFIG ADJ TO220-7 RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT1371HV | 制造商:LINER 制造商全称:Linear Technology 功能描述:500kHz High Efficiency 3A Switching Regulator |
| LT1371HVCR | 功能描述:IC REG MULTI CONFIG ADJ 3A D2PAK RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT1371HVCR#PBF | 功能描述:IC REG MULTI CONFIG ADJ 3A D2PAK 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 |
| LT1371HVCR#PBF | 制造商:Linear Technology 功能描述:SP-SWREG/Monolithic Hi Sw Vol 制造商:Linear Technology 功能描述:SP-SWREG/Monolithic, Hi Sw Volt 500kHz,3 |
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