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參數(shù)資料
| 型號： | LT3845AMPFE#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 4.40 MM, LEAD FREE, PLASTIC, TSSOP-16 |
| 文件頁數(shù)： | 3/26頁 |
| 文件大?。?/td> | 284K |
| 代理商： | LT3845AMPFE#TRPBF |
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LT3845A
11
3845afa
Because the LT3845A uses a linear regulator to generate
VCC, power dissipation can become a concern with high
VIN voltages. Gate drive currents are typically in the range
of 5mA to 15mA per MOSFET, so gate drive currents can
create substantial power dissipation. It is advisable to
derive VCC and VBOOST power from an external source
whenever possible.
The onboard VCC regulator will provide gate drive power
for start-up under all conditions with total MOSFET gate
charge loads up to 180nC. The regulator can operate the
LT3845A continuously, provided the power dissipation
of the regulator does not exceed 250mW. The power
dissipation of the regulator is calculated as follows:
PD(REG) = (VIN – 8V) (fSW QG(TOTAL) + 3mA)
where QG(TOTAL) is the total MOSFET gate charge of the
TG and BG.
In applications where these conditions are exceeded, VCC
must be derived from an external source after start-up.
Maximum continuous regulator power dissipation may be
exceeded for short duration VIN transients.
In LT3845A converter applications with output voltages in
the 9V to 20V range, back-feeding VCC and VBOOST from
theconverteroutputistrivial,accomplishedbyconnecting
diodes from the output to these supply pins. Deriving
these supplies from output voltages greater than 20V will
requireadditionalregulationtoreducethefeedbackvoltage.
Outputs lower than 9V will require step-up techniques to
increase the feedback voltage to something greater than
the 8V VCC regulated output. Low power boost switchers
are sometimes used to provide the step-up function, but
a simple charge-pump can perform this function in many
instances.
Burst Mode Operation
TheLT3845AemployslowcurrentBurstModefunctionality
to maximize efficiency during no load and low load
conditions. Burst Mode operation is enabled by shorting
the BURST_EN pin to SGND. Burst Mode operation can be
disabled by shorting BURST_EN to either VFB or VCC.
When the required switch current, sensed via the VC
pin voltage, is below 15% of maximum, the Burst Mode
operation is employed and that level of sense current is
APPLICATIONS INFORMATION
VOUT
1F
B0520
1F
Si1555DL
LT3845A
Charge Pump Doubler
Charge Pump Tripler
VCC
BG
VOUT
1F
B0520
1F
Si1555DL
LT3845A
VCC
BG
B0520
3845A AI01
TG
VOUT
3845A AI04
VCC
SW
BG
N
LT3845A
Inductor Auxiliary Winding
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| LT3845AIFE#TRPBF | SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16 |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT3845EFE | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Voltage Synchronous Current Mode Step-Down Controller with Adjustable Operating Frequency |
| LT3845EFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):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(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LT3845EFE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LT3845EFEPBF | 制造商:Linear Technology 功能描述:60V Current-Mode Controller Adj. TSSOP16 |
| LT3845EFE-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Voltage Synchronous Current Mode Step-Down Controller with Adjustable Operating Frequency |
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