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參數(shù)資料
| 型號： | LT3681EDE#TR |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 4.4 A SWITCHING REGULATOR, 3100 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封裝： | 4 X 3 MM, PLASTIC, DFN-14 |
| 文件頁數(shù)： | 4/24頁 |
| 文件大?。?/td> | 367K |
| 代理商： | LT3681EDE#TR |
LT3681
12
3681f
When choosing a capacitor, look carefully through the
data sheet to nd out what the actual capacitance is under
operating conditions (applied voltage and temperature).
A physically larger capacitor, or one with a higher voltage
rating, may be required. High performance tantalum or
electrolytic capacitors can be used for the output capacitor.
Low ESR is important, so choose one that is intended for
use in switching regulators. The ESR should be specied
by the supplier, and should be 0.05
Ω or less. Such a
capacitor will be larger than a ceramic capacitor and will
have a larger capacitance, because the capacitor must be
large to achieve low ESR. Table 2 lists several capacitor
vendors.
Catch Diode
The integral power Schottky catch diode conducts current
only during switch off time. Average forward current in
normal operation can be calculated from:
ID(AVG) = IOUT (VIN – VOUT)/VIN
where IOUT is the output load current.
Ceramic Capacitors
Ceramic capacitors are small, robust and have very low
ESR. However, ceramic capacitors can cause problems
when used with the LT3681 due to their piezoelectric nature.
When in Burst Mode operation, the LT3681’s switching
frequency depends on the load current, and at very light
loads the LT3681 can excite the ceramic capacitor at audio
frequencies, generating audible noise. Since the LT3681
operates at a lower current limit during Burst Mode op-
eration, the noise is typically very quiet to a casual ear.
If this is unacceptable, use a high performance tantalum
or electrolytic capacitor at the output.
A nal precaution regarding ceramic capacitors concerns
the maximum input voltage rating of the LT3681. A ceramic
input capacitor combined with trace or cable inductance
forms a high quality (under damped) tank circuit. If the
LT3681 circuit is plugged into a live supply, the input volt-
age can ring to twice its nominal value, possibly exceeding
the LT3681’s rating. This situation is easily avoided (see
the Hot Plugging Safely section).
Frequency Compensation
The LT3681 uses current mode control to regulate the
output. This simplies loop compensation. In particular, the
LT3681 does not require the ESR of the output capacitor
for stability, so you are free to use ceramic capacitors to
achieve low output ripple and small circuit size. Frequency
compensation is provided by the components tied to the
VC pin, as shown in Figure 2. Generally a capacitor (CC)
and a resistor (RC) in series to ground are used. In ad-
dition, there may be a lower value capacitor in parallel.
This capacitor (CF) is not part of the loop compensation
but is used to lter noise at the switching frequency, and
is required only if a phase-lead capacitor is used or if the
output capacitor has high ESR.
VENDOR
PHONE
URL
PART SERIES
COMMENTS
Panasonic
(714) 373-7366
www.panasonic.com
Ceramic,
Polymer,
Tantalum
EEF Series
Kemet
(864) 963-6300
www.kemet.com
Ceramic,
Tantalum
T494, T495
Sanyo
(408) 749-9714
www.sanyovideo.com
Ceramic,
Polymer,
Tantalum
POSCAP
Murata
(408) 436-1300
www.murata.com
Ceramic
AVX
www.avxcorp.com
Ceramic,
Tantalum
TPS Series
Taiyo Yuden
(864) 963-6300
www.taiyo-yuden.com
Ceramic
Table 2. Capacitor Vendors
APPLICATIONS INFORMATION
相關PDF資料 |
PDF描述 |
|---|---|
| LT3681EDE | 4.4 A SWITCHING REGULATOR, 3100 kHz SWITCHING FREQ-MAX, PDSO14 |
| LT3686AEMSE#PBF | 2.65 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO12 |
| LT3686AHMSE#TRPBF | 2.65 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO12 |
| LT3686AHMSE#PBF | 2.65 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO12 |
| LT3686AIMSE#TRPBF | 2.65 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO12 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LT3682 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:42V, 750mA Step-Down Regulator with 2.5μA |
| LT3682EDD#PBF | 功能描述:IC REG BUCK ADJ 1A 12DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關:2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應商設備封裝:6-SON（1.45x1） 產品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LT3682EDD#TRPBF | 功能描述:IC REG BUCK ADJ 1A 12DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應商設備封裝:10-MSOP 裸露焊盤 |
| LT3682EDD-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1A Micropower Step-Down |
| LT3682EDD-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1A Micropower Step-Down |
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