- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄44987 > LT3845AMPFE#TRPBF (LINEAR TECHNOLOGY CORP) SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16 PDF資料下載
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)： | 9/26頁 |
| 文件大小： | 284K |
| 代理商： | LT3845AMPFE#TRPBF |
LT3845A
17
3845afa
DVIN is typically chosen at a level acceptable to the user.
100mV to 200mV is a good starting point. Aluminum elec-
trolytic capacitors are a good choice for high voltage, bulk
capacitance due to their high capacitance per unit area.
The capacitor’s RMS current is:
ICIN(RMS) =IOUT
VOUT(VIN – VOUT)
(VIN)
2
If applicable, calculate it at the worst case condition,
VIN = 2VOUT. The RMS current rating of the capacitor
is specified by the manufacturer and should exceed the
calculated ICIN(RMS). Due to their low ESR (Equivalent
Series Resistance), ceramic capacitors are a good choice
for high voltage, high RMS current handling. Note that the
ripplecurrentratingsfromaluminumelectrolyticcapacitor
manufacturersarebasedon2000hoursoflife.Thismakes
it advisable to further derate the capacitor or to choose a
capacitor rated at a higher temperature than required.
The combination of aluminum electrolytic capacitors and
ceramic capacitors is an economical approach to meeting
the input capacitor requirements. The capacitor voltage
rating must be rated greater than VIN(MAX). Multiple
capacitors may also be paralleled to meet size or height
requirementsinthedesign.Locatethecapacitorveryclose
to the MOSFET switch and use short, wide PCB traces to
minimize parasitic inductance.
Output Capacitor Selection
The output capacitance, COUT, selection is based on the
design’s output voltage ripple,
DVOUT and transient load
requirements.
DVOUT is a function of DIL and the COUT
ESR. It is calculated by:
DVOUT =DIL ESR+
1
(8 fSW COUT)
APPLICATIONS INFORMATION
The maximum ESR required to meet a
DVOUT design
requirement can be calculated by:
ESR(MAX)
=
(
DVOUT)(L)(fSW)
VOUT 1–
VOUT
VIN(MAX)
Worst-case
DVOUT occurs at highest input voltage. Use
paralleled multiple capacitors to meet the ESR requirements.
IncreasingtheinductanceisanoptiontolowertheESRrequire-
ments. For extremely low
DVOUT, an additional LC filter stage
can be added to the output of the supply. Application Note
44 has some good tips on sizing an additional output filter.
Output Voltage Programming
A resistive divider sets the DC output voltage according
to the following formula:
R2
=R1
VOUT
1.231V
– 1
The external resistor divider is connected to the output of
theconverterasshowninFigure3.Toleranceofthefeedback
resistors will add additional error to the output voltage.
Example: VOUT = 12V; R1 = 10k
R2
=10k 12V
1.231V
1
=87.48kuse 86.6k 1%
The VFB pin input bias current is typically 25nA, so use
of extremely high value feedback resistors could cause a
converter output that is slightly higher than expected. Bias
current error at the output can be estimated as:
DVOUT(BIAS) = 25nA R2
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT3845AIFE#TRPBF | SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16 |
| LT3845AMPFE#PBF | SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16 |
| LT3845EFE#TR | SWITCHING CONTROLLER, 600 kHz SWITCHING FREQ-MAX, PDSO16 |
| LT3956IUHE#TRPBF | SWITCHING REGULATOR, PQCC36 |
| LT3957EUHE#TRPBF | SWITCHING REGULATOR, PQCC36 |
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 標準包裝: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:- 標準包裝: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 |
發(fā)布緊急采購，3分鐘左右您將得到回復。