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| 型号： | LT3758EDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 16/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK INV 10DFN |
| 标准包装： | 121 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 电源电压： | 5.5 V ~ 100 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 是 |
| 反相： | 是 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1340 (CN2011-ZH PDF) |
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LT3758/LT3758A
APPLICATIONS INFORMATION
V IN(MIN)
? I L ? f
I L(PEAK) = I L(MAX) ? ? 1 + ?
c 2
I L(RMS) = I L(MAX) ? 1 +
Theconstantcintheprecedingequationrepresentsthe
percentage peak-to-peak ripple current in the inductor,
relative to I L(MAX) .
The inductor ripple current has a direct effect on the choice
of the inductor value. Choosing smaller values of ?I L
requires large inductances and reduces the current loop
gain (the converter will approach voltage mode). Accepting
larger values of ?I L provides fast transient response and
allows the use of low inductances, but results in higher input
current ripple and greater core losses. It is recommended
that c fall within the range of 0.2 to 0.6.
Given an operating input voltage range, and having chosen
the operating frequency and ripple current in the inductor,
the inductor value of the boost converter can be determined
using the following equation:
L = ? D MAX
The peak and RMS inductor current are:
? c ?
? 2 ?
12
Based on these equations, the user should choose the
inductors having sufficient saturation and RMS current
ratings.
Set the sense voltage at I L(PEAK) to be the minimum of the
SENSE current limit threshold with a 20% margin. The
sense resistor value can then be calculated to be:
The power MOSFET will see full output voltage, plus a
diode forward voltage, and any additional ringing across
its drain-to-source during its off-time. It is recommended
to choose a MOSFET whose B VDSS is higher than V OUT by
a safety margin (a 10V safety margin is usually sufficient).
The power dissipated by the MOSFET in a boost converter is:
P FET = I 2L(MAX) ? R DS(ON) ? D MAX + 2 ? V 2OUT ? I L(MAX)
? C RSS ? f/1A
The first term in the preceding equation represents the
conduction losses in the device, and the second term, the
switching loss. C RSS is the reverse transfer capacitance,
which is usually specified in the MOSFET characteristics.
For maximum efficiency, R DS(ON) and C RSS should be
minimized. From a known power dissipated in the power
MOSFET, its junction temperature can be obtained using
the following equation:
T J = T A + P FET ? θ JA = T A + P FET ? ( θ JC + θ CA )
T J must not exceed the MOSFET maximum junction
temperature rating. It is recommended to measure the
MOSFET temperature in steady state to ensure that absolute
maximum ratings are not exceeded.
Boost Converter: Output Diode Selection
To maximize efficiency, a fast switching diode with low
forward drop and low reverse leakage is desirable. The
peak reverse voltage that the diode must withstand is
equal to the regulator output voltage plus any additional
ringing across its anode-to-cathode during the on-time.
The average forward current in normal operation is equal
to the output current, and the peak current is equal to:
I D(PEAK) = I L(PEAK) = ? 1 + ? ? I L(MAX)
R SENSE =
80mV
I L(PEAK)
? 2 ?
? c ?
Boost Converter: Power MOSFET Selection
Important parameters for the power MOSFET include the
drain-source voltage rating (V DS ), the threshold voltage
(V GS(TH) ), the on-resistance (R DS(ON) ), the gate to source
and gate to drain charges (Q GS and Q GD ), the maximum
drain current (I D(MAX) ) and the MOSFET’s thermal
resistances (R θ JC and R θ JA ).
It is recommended that the peak repetitive reverse voltage
rating V RRM is higher than V OUT by a safety margin (a 10V
safety margin is usually sufficient).
The power dissipated by the diode is:
P D = I O(MAX) ? V D
and the diode junction temperature is:
T J = T A + P D ? R θ JA
3758afd
16
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| LT3758EMSE#PBF | 功能描述:IC REG CTRLR PWM CM 10-MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LT3758EMSE#PBF | 制造商:Linear Technology 功能描述:DC-DC CONTROLLER INVERTING 1 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, INVERTING, 1MHZ, MSOP- |
| LT3758EMSE#TRPBF | 功能描述:IC REG CTRLR PWM CM 10-MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
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