- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄39425 > LTC3775EMSE#TRPBF (LINEAR TECHNOLOGY CORP) SWITCHING CONTROLLER, 575 kHz SWITCHING FREQ-MAX, PDSO16 PDF資料下載
參數(shù)資料
| 型號： | LTC3775EMSE#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 575 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | LEAD FREE, PLASTIC, MSOP-16 |
| 文件頁數(shù)： | 13/34頁 |
| 文件大小： | 534K |
| 代理商： | LTC3775EMSE#TRPBF |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁當前第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁第33頁第34頁
LTC3775
20
3775fa
INTVCC when the switch node is low. When the top MOSFET
turns on, the switch node rises to VIN and the BOOST pin
rises to approximately VIN + INTVCC. The boost capacitor
needs to store at least 100 times the gate charge required
by the top MOSFET. In most applications a 0.1μF to 1μF
X5R or X7R dielectric capacitor is adequate. The reverse
breakdown of the Schottky diode, DB, must be greater
than VIN(MAX).
Power MOSFET Selection
The LTC3775 requires two external N-channel power
MOSFETs, one for the top (main) switch and one for the
bottom (synchronous) switch. Important parameters for
the power MOSFETs are the threshold voltage V(GS)TH,
breakdown voltage V(BR)DSS, maximum current IDS(MAX),
on-resistance RDS(ON) and input capacitance.
The gate drive voltage is set by the 5.2V INTVCC supply.
Consequently, logic-level threshold MOSFETs must be
used in LTC3775 applications. If the INTVCC voltage is
expected to drop below 5V, then sub-logic level threshold
MOSFETs should be considered. Pay close attention to the
V(BR)DSS specication because most logic-level MOSFETs
are limited to 30V or less. The MOSFETs selected should
have a V(BR)DSS rating greater than the maximum input
voltage and some margin should be added for transients
and spikes.
MOSFET input capacitance is a combination of several
components but can be taken from the typical “gate charge”
curve included on most data sheets (Figure 15). The curve
is generated by forcing a constant input current into the
gate of a common source, current source loaded stage
and then plotting the gate voltage versus time. The initial
slope is the effect of the gate-to-source and the gate-
to-drain capacitance. The at portion of the curve is the
result of the Miller multiplication effect of the drain-to-gate
capacitance as the drain voltage drops. The upper sloping
line is due to the drain-to-gate accumulation capacitance
and the gate-to-source capacitance. The Miller charge (the
increase in coulombs on the horizontal axis from a to b
while the curve is at) is specied for a given VDS drain
voltage, but can be adjusted for different VDS voltages by
multiplying by the ratio of the application VDS to the curve
specied VDS values. To estimate the capacitance CMILLER,
take the change in gate charge from points a and b on a
manufacturer’s data sheet and divide by the stated VDS
voltage specied. CMILLER is the most important selec-
tion criteria for determining the transition loss term in
the top MOSFET but is not directly specied on MOSFET
data sheets. CRSS and COS are specied sometimes but
denitions of these parameters are not included.
When the controller is operating in continuous mode the
duty cycles for the top and bottom MOSFETs are given
by:
Top Gate Duty Cycle =
VOUT
VIN
Bottom Gate Duty Cycle =
VIN –VOUT
VIN
The power dissipation for the top and bottom MOSFETs
at maximum output current are given by:
PTOP =
VOUT
VIN
IOUT MAX)
2
()
(T(TOP)
() RDS(ON)(MAX)
()
+VIN
2
IOUT(MAX)
2
RDR
() CMILLER
()
1
INTVCC –VTH(IL)
+
1
VTH(IL)
fSW
PBOT =
VIN –VOUT
VIN
IOUT( AX)
2
()
MT(TOP)
() RDS(ON)(MAX)
()
where:
RDR = Effective top driver resistance
VTH(IL) = MOSFET data sheet specied typical gate
threshold voltage at the specied drain current
APPLICATIONS INFORMATION
+
–
VDS
VIN
VGS
MILLER EFFECT
QIN
ab
CMILLER = (QB – QA)/VDS
VGS
V
+
–
3775 F15
Figure 15. Gate Charge Characteristics
相關PDF資料 |
PDF描述 |
|---|---|
| LTC3775IMSE#PBF | SWITCHING CONTROLLER, 575 kHz SWITCHING FREQ-MAX, PDSO16 |
| LTC3805MPMSE#PBF | SWITCHING REGULATOR, 700 kHz SWITCHING FREQ-MAX, PDSO10 |
| LTC3805MPMSE#TR | SWITCHING REGULATOR, 700 kHz SWITCHING FREQ-MAX, PDSO10 |
| LTC3829IFE#PBF | SWITCHING REGULATOR, PDSO38 |
| LTC3829IFE#TRPBF | SWITCHING REGULATOR, PDSO38 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3775EUD#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN 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) |
| LTC3775EUD#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN DC/DC CONTROLLER QFN16 |
| LTC3775EUD#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN 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) |
| LTC3775IMSE#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-MSOP 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) |
| LTC3775IMSE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-MSOP 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) |
發(fā)布緊急采購，3分鐘左右您將得到回復。