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参数资料
| 型号： | LT3579EFE-1#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PDSO20 |
| 封装： | 4.40 MM, LEAD FREE, PLASTIC, TSSOP-20 |
| 文件页数： | 19/40页 |
| 文件大小： | 503K |
| 代理商： | LT3579EFE-1#PBF |
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LT3579/LT3579-1
26
35791f
appenDix
Maximum Inductance
Excessive inductance can reduce ripple current to levels
thataredifficultforthecurrentcomparator(A4intheBlock
Diagram) to cleanly discriminate, thus causing duty cycle
jitter and/or poor regulation. The maximum inductance
can be calculated by:
LMAX =
VIN VCESAT
(
)DC
fOSC 0.5A
where:
LMAX = L1 for Boost Topologies (see Figure 6)
LMAX = L1 = L2 for Coupled Dual Inductor
Topologies (see Figures 7 and 8)
LMAX = L1 || L2 for Uncoupled Dual Inductor
Topologies (see Figures 7 and 8)
Inductor Current Rating
The inductor(s) must have a rating greater than its (their)
peakoperatingcurrenttopreventinductorsaturation,which
would result in catastrophic failure and efficiency losses.
The maximum inductor current (considering start-up and
steady-state conditions) is given by:
IL_PEAK = ILIM +
VIN TMIN_PROP
L
where:
IL_PEAK
= Peak Inductor Current in L1 for a Boost
Topology, or the sum of the Peak
Inductor Currents in L1 and L2 for Dual
Inductor Topologies.
ILIM
= For Hard-Saturation Inductors, 9.4A with
SW1 and SW2 Tied Together, or 5.1A
with just SW1 used. For Soft-Saturation
Inductors, 6A with SW1 and SW2 Tied
Together, or 3.4A with just SW1 used.
TMIN_PROP = 100ns (Propagation Delay through the
Current Feedback Loop).
Note that these equations offer conservative results for
the required inductor current ratings. The current ratings
could be lower for applications with light loads, provided
the SS capacitor is sized appropriately to limit inductor
currents at start-up.
DIODE SELECTION
Schottky diodes, with their low forward voltage drops and
fast switching speeds, are recommended for use with the
LT3579. Choose a Schottky with low parasitic capacitance
to reduce reverse current spikes through the power switch
of the LT3579. The Diodes Inc. MBRM360 is a very good
choice with a 60V reverse voltage rating and an average
forward current of 3A.
OUTPUT CAPACITOR SELECTION
Low ESR (equivalent series resistance) capacitors should
be used at the output to minimize the output ripple voltage.
Multilayer ceramic capacitors are an excellent choice, as
they have an extremely low ESR and are available in very
small packages. X5R or X7R type are preferred, as these
materials retain their capacitance over wide voltage and
temperature ranges. A 22μF to 47μF output capacitor is
sufficient for most applications, but systems with low
output currents may need only 4.7μF to 22μF. Always
use a capacitor with a sufficient voltage rating. Many
ceramic capacitors, particularly 0805 or 0603 case sizes,
have greatly reduced capacitance at the desired output
voltage. Tantalum polymer or OS-CON capacitors can be
used, but it is likely that these capacitors will occupy more
board area than a ceramic, and will have higher ESR with
greater output ripple.
INPUT CAPACITOR SELECTION
Ceramic capacitors make a good choice for the input
decoupling capacitor, CVIN, which should be placed as
close as possible to the VINpinoftheLT3579.Thisensures
that the voltage seen at the VIN pin of the LT3579 remains
a nearly flat DC voltage. A 1μF to 4.7μF input capacitor is
sufficient for most applications.
A ceramic bypass capacitor, CPWR, should also be placed
as close as possible to the input of the inductor. This
ensures that the inductor ripple current is supplied from
the bypass capacitor and provides a nearly flat DC voltage
to the input of the voltage converter. A 4.7F to 10F input
power capacitor is sufficient for most applications.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3579EFE-1-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection |
| LT3579EFE-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection |
| LT3579EFE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection |
| LT3579EUFD#PBF | 功能描述:IC REG MULTI CONFIG SYNC 20QFN 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 |
| LT3579EUFD#TRPBF | 功能描述:IC REG MULTI CONFIG SYNC 20QFN 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 |
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