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| 型号： | LTC3417AEFE-1#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ DL 20TSSOP |
| 标准包装： | 74 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 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： | 1.5MHz，600kHz ~ 4MHz |
| 电流 - 输出： | 1A，1.5A |
| 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： | 20-TSSOP（0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 20-TSSOP-EP |
LTC3417A-1
APPLICATIONS INFORMATION
V OUT ( V IN – V OUT )
I RMS = ( I 1 + I 2 )
I L ESR COUT +
8 ? f O ? C OUT
When D1 = D2 then the equation simpli?es to:
I RMS = ( I 1 + I 2 ) D ( 1– D )
or
V IN
where the maximum average output currents I 1 and I 2
equal the respective peak currents minus half the peak-
to-peak ripple currents:
Typically, once the ESR requirement is satis?ed, the
capacitance is adequate for ?ltering. The output ripple
( Δ V OUT ) is determined by:
1
V OUT
where f O = operating frequency, C OUT = output capacitance
and Δ I L = ripple current in the inductor. The output ripple
is highest at maximum input voltage, since Δ I L increases
with input voltage. With Δ I L = 0.35I LOAD(MAX) , the output
ripple will be less than 100mV at maximum V IN and f O =
I 1 = I LIM1 –
I 2 = I LIM2 –
Δ I L1
2
Δ I L2
2
1MHz with:
ESR COUT < 150mΩ
Once the ESR requirements for C OUT have been met, the
RMS current rating generally far exceeds the I RIPPLE(P-P)
These formula have a maximum at V IN = 2V OUT , where
I RMS = (I 1 + I 2 )/2. This simple worst case is commonly
used to determine the highest I RMS .
For “out of phase” operation, the ripple current can be
lower than the “in phase” current.
In the “out of phase” case, the maximum I RMS does not
occur when V OUT1 = V OUT2 . The maximum typically oc-
curs when V OUT1 – V IN /2 = V OUT2 or when V OUT2 – V IN /2
= V OUT1 . As a good rule of thumb, the amount of worst
case ripple is about 75% of the worst case ripple in the
“in phase” mode. Also note that when V OUT1 = V OUT2 =
V IN /2 and I 1 = I 2 , the ripple is zero.
Note that capacitor manufacturer’s ripple current ratings
are often based on only 2000 hours lifetime. This makes
it advisable to further derate the capacitor, or choose a
capacitor rated at a higher temperature than required.
Several capacitors may also be paralleled to meet the
size or height requirements of the design. An additional
0.1μF to 1μF ceramic capacitor is also recommended on
V IN for high frequency decoupling, when not using an all
ceramic capacitor solution.
Output Capacitor (C OUT1 and C OUT2 ) Selection
The selection of C OUT1 and C OUT2 is driven by the required
ESR to minimize voltage ripple and load step transients.
requirement, except for an all ceramic solution.
In surface mount applications, multiple capacitors may
have to be paralleled to meet the capacitance, ESR or RMS
current handling requirement of the application. Aluminum
electrolytic, special polymer, ceramic and dry tantalum
capacitors are all available in surface mount packages. The
OS-CON semiconductor dielectric capacitor available from
Sanyo has the lowest ESR(size) product of any aluminum
electrolytic at a somewhat higher price. Special polymer
capacitors, such as Sanyo POSCAP, offer very low ESR, but
have a lower capacitance density than other types. Tantalum
capacitors have the highest capacitance density, but it has
a larger ESR and it is critical that the capacitors are surge
tested for use in switching power supplies. An excellent
choice is the AVX TPS series of surface tantalums, available
in case heights ranging from 2mm to 4mm. Aluminum
electrolytic capacitors have a signi?cantly larger ESR, and
are often used in extremely cost-sensitive applications
provided that consideration is given to ripple current
ratings and long term reliability. Ceramic capacitors have
the lowest ESR and cost but also have the lowest capaci-
tance density, high voltage and temperature coef?cient
and exhibit audible piezoelectric effects. In addition, the
high Q of ceramic capacitors along with trace inductance
can lead to signi?cant ringing. Other capacitor types
include the Panasonic specialty polymer (SP) capacitors.
3417a1fa
11
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相关代理商/技术参数 |
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|---|---|
| LTC3417AEFE-1-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous 1.5A/1A 4MHz Step-Down DC/DC Regulator with POR |
| LTC3417AEFE-2#PBF | 功能描述:IC REG BUCK SYNC ADJ DL 20TSSOP 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 |
| LTC3417AEFE-2#TRPBF | 功能描述:IC REG BUCK SYNC ADJ DL 20TSSOP 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 |
| LTC3417AEFE-2-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous 1.5A/1A 4MHz Step-Down DC/DC Regulator |
| LTC3417AEFE-2-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous 1.5A/1A 4MHz Step-Down DC/DC Regulator |
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