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參數資料
| 型號： | LTC3856IUH#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, PQCC38 |
| 封裝： | 5 X 5 MM, LEAD FREE, PLASTIC, MO-220WHHD-X, QFN-32 |
| 文件頁數： | 29/40頁 |
| 文件大?。?/td> | 2222K |
| 代理商： | LTC3856IUH#TRPBF |
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LTC3856
3856f
applicaTions inForMaTion
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of
the IC. These items are also illustrated graphically in the
layout diagram of Figure 17. Check the following in the
PC layout:
1. ArethesignalandpowergroundpathsKelvinconnected?
Keep the SGND at one end of a printed circuit path thus
preventing MOSFET currents from traveling under the
IC. The INTVCC decoupling capacitor should be placed
immediately adjacent to the IC between the INTVCC pin
and PGND plane. A 1F ceramic capacitor of the X7R or
X5R type is small enough to fit very close to the IC to
minimize the ill effects of the large current pulses drawn
to drive the bottom MOSFETs. An additional 5F to 10F
of ceramic, tantalum or other very low ESR capacitance
is recommended in order to keep the internal IC supply
quiet. The power ground returns to the sources of the
bottom N-channel MOSFETs, anodes of the Schottky
diodes and (–) plates of CIN,whichshouldhaveasshort
lead lengths as possible.
2. Does the IC DIFFP pin connect to the (+) plates of
COUT? A 30pF to 300pF feedforward capacitor between
the DIFFP and VFB pins should be placed as close as
possible to the IC.
3. Are the SENSE– and SENSE+ printed circuit traces for
each channel routed together with minimum PC trace
spacing? The filter capacitors between SENSE+ and
SENSE– for each channel should be as close as possible
to the pins of the IC. Connect the SENSE– and SENSE+
pins to the pads of the sense resistor as illustrated in
Figure 1.
4. Do the (+) plates of CPWR connect to the drains of the
topsideMOSFETsascloselyaspossible?Thiscapacitor
provides the pulsed current to the MOSFETs.
5. Keeptheswitchingnodes,SWn,BOOSTnandTGnaway
from sensitive small-signal nodes (SENSE+, SENSE–,
DIFFP, DIFFN, VFB, ITEMP). Ideally the SWn, BOOSTn
and TGn printed circuit traces should be routed away
and separated from the IC and especially the “quiet”
side of the IC. Separate the high dv/dt traces from sensi-
tive small-signal nodes with ground traces or ground
planes.
6. Usealowimpedancesourcesuchasalogicgatetodrive
the PLLIN pin and keep the lead as short as possible.
7. The 47pF to 330pF ceramic capacitor between the ITH
pin and signal ground should be placed as close as pos-
sible to the IC. Figure 17 illustrates all branch currents
in a 2-phase switching regulator. It becomes very clear
after studying the current waveforms why it is critical to
keepthehighswitchingcurrentpathstoasmallphysical
size. High electric and magnetic fields will radiate from
these loops just as radio stations transmit signals. The
output capacitor ground should return to the negative
terminal of the input capacitor and not share a common
ground path with any switched current paths. The left
half of the circuit gives rise to the noise generated by
a switching regulator. The ground terminations of the
synchronous MOSFETs and Schottky diodes should
return to the bottom plate(s) of the input capacitor(s)
with a short isolated PC trace since very high switched
currents are present. External OPTI-LOOP compensa-
tion allows overcompensation for PC layouts which are
not optimized, but this is not the recommended design
procedure.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LTC3857EGN-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數:1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3857EGN-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數:1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC3857EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數:1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3857EUH#PBF | 制造商:Linear Technology 功能描述:IC DUAL SYNC STEP-DOWN CONTROLLER QFN-32 |
| LTC3857EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數:1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
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