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參數(shù)資料
| 型號： | LTC3617EUDD#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 14 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PQCC24 |
| 封裝： | 3 X 5 MM, LEAD FREE, PLASTIC, QFN-24 |
| 文件頁數(shù)： | 3/20頁 |
| 文件大小： | 471K |
| 代理商： | LTC3617EUDD#PBF |
LTC3617
11
3617fa
applications inForMation
Inductor Selection
For a given input and output voltage, the inductor value
and operating frequency determine the ripple current. The
ripple current
IL increases with higher VIN and decreases
with higher inductance:
IL =
VOUT
fSW L
1–
VOUT
VIN
Having a lower ripple current reduces the core losses
in the inductor, the ESR losses in the output capacitors
and the output voltage ripple. A reasonable starting point
for selecting the ripple current is
IL = 0.3 IOUT(MAX).
The largest ripple current occurs at the highest VIN. To
guarantee that the ripple current stays below a specified
maximum, the inductor value should be chosen according
to the following equation:
L
=
VOUT
fSW IL(MAX)
1–
VOUT
VIN(MAX)
Inductor Core Selection
Once the value for L is known, the type of inductor must be
selected. Actual core loss is independent of core size for a
fixed inductor value, but it is very dependent on the induc-
tanceselected.Astheinductanceincreases,corelossesde-
crease.Unfortunately,increasedinductancerequiresmore
turns of wire and therefore, copper losses will increase.
Ferrite designs have very low core losses and are pre-
ferred at high switching frequencies, so design goals can
concentrate on copper loss and preventing saturation.
Ferrite core material saturates “hard,” meaning that induc-
tance collapses abruptly when the peak design current is
exceeded. This results in an abrupt increase in inductor
ripple current and consequently output voltage ripple. Do
not allow a ferrite core to saturate!
Different core materials and shapes will change the size/
currentandprice/currentrelationshipofaninductor.Toroid
or shielded pot cores in ferrite or permalloy materials are
small and don’t radiate much energy, but generally cost
more than powdered iron core inductors with similar
characteristics. The choice of which style inductor to use
mainly depends on the price versus size requirements
and any radiated field/EMI requirements. Table 1 shows
some typical surface mount inductors that work well in
LTC3617 applications.
Input Capacitor (CIN) Selection
In continuous mode, the source current of the top P-
channel MOSFET is a square wave of duty cycle VOUT/
VIN. To prevent large input voltage transients, a low ESR
capacitor sized for the maximum RMS current must be
used at VIN.
The maximum RMS capacitor current is given by:
IRMS =IOUT(MAX)
VOUT
VIN
VIN
VOUT
– 1
ThisformulahasamaximumatVIN=2VOUT,whereIRMS=
IOUT/2.Thissimpleworst-caseconditioniscommonlyused
for design because even significant deviations do not offer
much relief. Note that ripple current ratings from capacitor
manufacturers are often based on only 2000 hours of life
which makes it advisable to further derate the capacitor,
or choose a capacitor rated at a higher temperature than
required.Severalcapacitorsmayalsobeparalleledtomeet
size or height requirements in the design.
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參數(shù)描述 |
|---|---|
| LTC3617IUDD#PBF | 功能描述:IC REG SYNC 6A BUCK 24QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3617IUDD#TRPBF | 功能描述:IC REG SYNC 6A BUCK 24QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3618EFE#PBF | 功能描述:IC REG DUAL SYNC 3A BUCK 24TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3618EFE#TRPBF | 功能描述:IC REG DUAL SYNC 3A BUCK 24TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3618EUF#PBF | 功能描述:IC REG DUAL SYNC 3A BUCK 24QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
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