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參數(shù)資料
| 型號(hào)： | LT1680 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | High Power DC/DC Step-Up Controller(大功率，DC/DC步升轉(zhuǎn)換器) |
| 中文描述： | 高功率DC / DC升壓控制器（大功率，直流/直流步升轉(zhuǎn)換器） |
| 文件頁數(shù)： | 14/16頁 |
| 文件大?。?/td> | 272K |
| 代理商： | LT1680 |
14
LT1680
APPLICATIO
S I
N
FOR
ATIO
U
Setting the resistor divider reference voltage to 2V assures
that the additional compensation waveform will be en-
abled at a 75% duty cycle. As shown in Figure 11a, using
R
SL1
= 45k and R
SL2
= 30k sets the desired reference
voltage and has a R
TH
of 18k, which meets both design
requirements. Figure 11b shows the slope compensation
effective waveforms both with and without the SL/ADJ
external resistors.
W
U
In a typical LT1680 boost converter, the switch current is
equal to the inductor current, but is chopped according to
duty cycle (DC). The conduction loss (P
LOSS
) for a given
FET R
DS(ON)
can be calculated using the relation:
P
LOSS
≈
(DC)(R
DS(ON)
)(I
AVG2
+ [
I
2
/12])
where I
AVG
= average inductor current and
I = peak-to-
peak inductor ripple current.
The output diode is often a major source of power loss in
switching regulators and selection of adequately rated
diodes is important. In a boost converter, when the output
voltage is significantly higher than the input voltage, the
peak diode current becomes much higher than average
output currents and diode current ratings must be ob-
served with caution. The peak diode current is:
I
D(PEAK)
= I
AVG
+
I/2
and the average power dissipation (P
D
) in the diode is:
P
D
= (I
OUT
)(V
f
)
where V
f
is the forward voltage of the diode at peak
current. The output diode must also be rated for maximum
reverse voltages exceeding V
OUT
.
C
IN
and C
OUT
Supply Decoupling Capacitor Selection
The large currents typical of LT1680 applications require
special consideration for the regulator input and output
supply decoupling capacitors.
Under normal steady state boost operation, output current
provided by the converter is a square wave of duty cycle V
IN
/
V
OUT
, the average value being equal to the required DC load
current (I
OUT
). The continuity of the load current is main-
tained by the output bypass capacitors. To prevent exces-
sive output voltage ripple and undue capacitor heating (and
associated catastrophic failure), low ESR output capacitors
sized for the maximum RMS current must be used. This
maximum capacitor RMS current follows the relation:
I
I
V
V
RMS
OUT
OUT
IN
≈
–
/
1
1 2
Capacitor ripple current ratings are often based on only 2000
hours (3 months) lifetime; it is advisable to derate either the
ESR or temperature rating of capacitors for increased MTBF.
Figure 11a. External Slope Compensation Resistors
16
1
R
SL1
45k
R
SL2
30k
1680 F11a
5V
REF
SL/ADJ
LT1680
(0.084 + 0.139)(f
O
)
R
SENSE
(0.084)(f
O
)
R
SENSE
2.5V
2V
0.8V
DC = 0.75
1680 F11b
Figure 11b. Slope Compensation Waveforms
Power MOSFET and Output Rectifying Diode Selection
LT1680 converter system parameters that dictate selec-
tion criteria for the switch MOSFET and output rectifying
diode include maximum load current (I
OUT
), inductor
average current (I
AVG
) and inductor ripple current (
I),
and maximum input and output voltages.
The switch MOSFETs selected must have a maximum
operatingV
DSS
exceeding the maximum output voltage
(V
OUT
). V
GS
rated operating maximums must exceed the
12V
IN
supply voltage. Once voltage requirements have
been determined, switch conduction resistance (R
DS(ON)
)
can be determined based on allowable power dissipation.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1680C | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Power DC/DC Step-Up Controller |
| LT1680CN | 功能描述:IC REG CTRLR BST PWM CM 16-DIP RoHS:否 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) |
| LT1680CN#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-DIP 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 |
| LT1680CSW | 功能描述:IC REG CTRLR BST PWM CM 16-SOIC RoHS:否 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) |
| LT1680CSW#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-SOIC 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 |
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