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参数资料
| 型号： | LT3957EUHE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/28页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG ADJ 36VQFN |
| 特色产品： | LT?3957/LT?3958 Converters |
| 标准包装： | 61 |
| 类型： | 升压（升压），反相，回扫，Sepic |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.6 V ~ 40 V |
| 输入电压： | 3 V ~ 40 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz ~ 1MHz |
| 电流 - 输出： | 5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 36-WFQFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 36-QFN-EP（6x5） |
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LT3957
APPLICATIONS INFORMATION
The power dissipated by the diode is:
P D = I O(MAX) ? V D
t ON
t OFF
V COUT
where V D is diode’s forward voltage drop, and the diode
junction temperature is:
T J = T A + P D ? R θ JA
V OUT
(AC)
V ESR
RINGING DUE TO
TOTAL INDUCTANCE
(BOARD + CAP)
3957 F05
The R θ JA to be used in this equation normally includes the
R θ JC for the device plus the thermal resistance from the board
to the ambient temperature in the enclosure. T J must not
exceed the diode maximum junction temperature rating.
Boost Converter: Output Capacitor Selection
Figure 5. The Output Ripple Waveform of a Boost Converter
The output capacitor in a boost regulator experiences high
RMS ripple currents, as shown in Figure 5. The RMS ripple
current rating of the output capacitor can be determined
using the following equation:
Contributions of ESR (equivalent series resistance), ESL
(equivalent series inductance) and the bulk capacitance
must be considered when choosing the correct output
I RMS(COUT) ≥ I O(MAX) ?
D MAX
1 ? D MAX
ESR COUT ≤
capacitors for a given output ripple voltage. The effect of
these three parameters (ESR, ESL and bulk C) on the output
voltage ripple waveform for a typical boost converter is
illustrated in Figure 5.
The choice of component(s) begins with the maximum
acceptable ripple voltage (expressed as a percentage of
the output voltage), and how this ripple should be divided
between the ESR step Δ V ESR and the charging/discharg-
ing Δ V COUT . For the purpose of simplicity, we will choose
2% for the maximum output ripple, to be divided equally
between Δ V ESR and Δ V COUT . This percentage ripple will
change, depending on the requirements of the application,
and the following equations can easily be modi?ed. For a
1% contribution to the total ripple voltage, the ESR of the
output capacitor can be determined using the following
equation:
0.01? V OUT
I D(PEAK)
For the bulk C component, which also contributes 1% to
the total ripple:
Multiple capacitors are often paralleled to meet ESR require-
ments. Typically, once the ESR requirement is satis?ed, the
capacitance is adequate for ?ltering and has the required
RMS current rating. Additional ceramic capacitors in par-
allel are commonly used to reduce the effect of parasitic
inductance in the output capacitor, which reduces high
frequency switching noise on the converter output.
Boost Converter: Input Capacitor Selection
The input capacitor of a boost converter is less critical
than the output capacitor, due to the fact that the inductor
is in series with the input, and the input current wave-
form is continuous. The input voltage source impedance
determines the size of the input capacitor, which is typi-
cally in the range of 1μF to 100μF. A low ESR capacitor
is recommended, although it is not as critical as for the
output capacitor.
The RMS input capacitor ripple current for a boost con-
verter is:
I RMS(CIN) = 0.3 ? Δ I L
C OUT ≥
I O(MAX)
0.01? V OUT ? ?
3957f
15
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3957EUHETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch |
| LT3957IUHE#PBF | 功能描述:IC REG MULTI CONFIG ADJ 36VQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3957IUHE#TRPBF | 功能描述:IC REG MULTI CONFIG ADJ 36VQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3957IUHEPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch |
| LT3957IUHETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch |
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