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參數(shù)資料
| 型號： | LTC3565EMSE#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2.5 A SWITCHING REGULATOR, 4000 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | LEAD FREE, PLASTIC, MSOP-10 |
| 文件頁數(shù)： | 5/22頁 |
| 文件大?。?/td> | 587K |
| 代理商： | LTC3565EMSE#TRPBF |
LTC3565
3565fa
is adequate for filtering. The output ripple (
ΔVOUT) is
determined by:
ΔVOUT ≈ ΔIL ESR +
1
8fOCOUT
where f = operating frequency, COUT = output capacitance
and
ΔIL = ripple current in the inductor. The output ripple
is highest at maximum input voltage since
ΔIL increases
with input voltage. With
ΔIL = 0.4 IOUT(MAX), the output
ripplewillbelessthan100mVatmaximumVIN,aminimum
COUT of 10F and fO = 1MHz with:
ESRCOUT < 150mΩ
Once the ESR requirements for COUT have been met, the
RMS current rating generally far exceeds the IRIPPLE(P-P)
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
currenthandlingrequirementoftheapplication.Aluminum
electrolytic, special polymer, ceramic and dry tantalum
capacitorsareallavailableinsurfacemountpackages.The
OS-CONsemiconductordielectriccapacitoravailablefrom
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.
Tantalumcapacitorshavethehighestcapacitancedensity,
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
mount tantalums, available in case heights ranging from
2mm to 4mm. Aluminum electrolytic capacitors have a
significantly larger ESR, and is 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 capacitance density, a high voltage and
temperature coefficient and exhibit audible piezoelectric
effects. In addition, the high Q of ceramic capacitors along
with trace inductance can lead to significant ringing. Other
capacitor types include the Panasonic specialty polymer
(SP) capacitors.
In most cases, 0.1F to 1F of ceramic capacitors should
also be placed close to the LTC3565 in parallel with the
main capacitors for high frequency decoupling.
Ceramic Input and Output Capacitors
Higher value, lower cost ceramic capacitors are now be-
coming available in smaller case sizes. Their high ripple
current, high voltage rating and low ESR make them
ideal for switching regulator applications. Because the
LTC3565’s control loop does not depend on the output
capacitor’s ESR for stable operation, ceramic capacitors
can be used freely to achieve very low output ripple and
small circuit size.
However, care must be taken when ceramic capacitors are
used at the input. When a ceramic capacitor is used at the
input and the power is supplied by a wall adapter through
long wires, a load step at the output can induce ringing at
the input, VIN.Atbest,thisringingcancoupletotheoutput
and be mistaken as loop instability. At worst, a sudden
inrush of current through the long wires can potentially
cause a voltage spike at VIN large enough to damage the
part. Refer to Linear Technology Application Note 88 for
a detailed discussion of this potential issue.
When choosing the input and output ceramic capacitors,
choose the X5R or X7R dielectric formulations. These
dielectrics have the best temperature and voltage charac-
teristics of all the ceramics for a given value and size.
Since the ESR of a ceramic capacitor is so low, the input
and output capacitor must instead fulfill a charge storage
requirement.Duringaloadstep,theoutputcapacitormust
instantaneously supply the current to support the load
until the feedback loop raises the switch current enough
to support the load. The time required for the feedback
loop to respond is dependent on the compensation com-
ponents and the output capacitor value. Typically, 3 to 4
cycles are required to respond to a load step, but only in
the first cycle does the output drop linearly. The output
droop, VDROOP, is usually about 2 to 3 times the linear
applications inForMation
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相關(guān)代理商/技術(shù)參數(shù) |
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| LTC3565IDD | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3565IDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LTC3565IDD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC |
| LTC3565IDDPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3565IDD-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
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