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参数资料
| 型号： | LTC3418EUHF#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 8A 38QFN |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 5 V |
| 输入电压： | 2.25 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 1MHz |
| 电流 - 输出： | 8A |
| 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： | 38-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 38-QFN（5x7） |
LTC3418
APPLICATIONS INFORMATION
The basic LTC3418 application circuit is shown on the front
page of this data sheet. External component selection is
determined by the maximum load current and begins with
the selection of the operating frequency and inductor value
followed by C IN and C OUT .
Operating Frequency
Selection of the operating frequency is a tradeoff between
ef ?ciency and component size. High frequency operation
allows the use of smaller inductor and capacitor values.
Having a lower ripple current reduces the core losses in
the inductor, the ESR losses in the output capacitors and
the output voltage ripple. Highest ef ?ciency operation is
achieved at low frequency with small ripple current. This,
however, requires a large inductor.
A reasonable starting point for selecting the ripple current
is Δ I L = 0.4(I MAX ). The largest ripple current occurs at the
highest V IN . To guarantee that the ripple current stays
below a speci?ed maximum, the inductor value should
be chosen according to the following equation:
Operation at lower frequencies improves ef ?ciency by
reducing internal gate charge losses but requires larger
inductance values and/or capacitance to maintain low
output ripple voltage.
L =
V OUT
f I L(MAX)
1–
V OUT
V IN(MAX)
The operating frequency of the LTC3418 is determined
by an external resistor that is connected between the R T
pin and ground. The value of the resistor sets the ramp
current that is used to charge and discharge an internal
timing capacitor within the oscillator and can be calculated
by using the following equation:
? ?
R OSC = 7.3 ? 10 10 ? Ω ? – 2.5k Ω
f
Although frequencies as high as 4MHz are possible, the
minimum on-time of the LTC3418 imposes a minimum
limit on the operating duty cycle. The minimum on-time
is typically 80ns. Therefore, the minimum duty cycle is
equal to:
100 ? 80ns ? f(Hz)
Inductor Selection
For a given input and output voltage, the inductor value
and operating frequency determine the ripple current. The
ripple current Δ I L increases with higher V IN or V OUT and
decreases with higher inductance:
The inductor value will also have an effect on Burst Mode
operation. The transition from low current operation
begins when the peak inductor current falls below a level
set by the burst clamp. Lower inductor values result in
higher ripple current which causes this to occur at lower
load currents. This causes a dip in ef ?ciency in the upper
range of low current operation. In Burst Mode operation,
lower inductance values will cause the burst frequency
to increase.
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 ?xed inductor value, but it is very dependent on the
inductance selected. As the inductance increases, core
losses decrease. Unfortunately, increased inductance
requires more 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,” which means that
I L =
V OUT
fL
1–
V OUT
V IN
inductance collapses abruptly when the peak design current
is exceeded. This results in an abrupt increase in inductor
ripple current and consequent output voltage ripple. Do
not allow the core to saturate!
3418fb
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3419 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Monolithic 600mA Synchronous Step-Down Regulator |
| LTC3419EDD | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Monolithic 600mA Synchronous Step-Down Regulator |
| LTC3419EDD#PBF | 功能描述:IC REG BUCK SYNC ADJ .6A DL 8DFN 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 |
| LTC3419EDD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ .6A DL 8DFN 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°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 |
| LTC3419EDD-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Monolithic 600mA Synchronous Step-Down Regulator |
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