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| 型号： | LT3958EUHE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 14/28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 ~ 80 V |
| 输入电压： | 5 V ~ 80 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz ~ 1MHz |
| 电流 - 输出： | 3.3A |
| 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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LT3958
APPLICATIONS INFORMATION
? ( 3.3A ? 0.5 ? Δ I SW )
I O(MAX) ≤
V OUT 1
V IN
1 ? D
APPLICATION CIRCUITS
The LT3958 can be con?gured as different topologies. The
?rst topology to be analyzed will be the boost converter,
followed by the ?yback, SEPIC and inverting converters.
Boost Converter: Switch Duty Cycle and Frequency
The LT3958 can be con?gured as a boost converter for
the applications where the converter output voltage is
higher than the input voltage. Remember that boost con-
verters are not short-circuit protected. Under a shorted
output condition, the inductor current is limited only by
the input supply capability. For applications requiring a
step-up converter that is short-circuit protected, please
refer to the Applications Information section covering
SEPIC converters.
The conversion ratio as a function of duty cycle is
=
in continuous conduction mode (CCM).
mum output current (I O(MAX) ) is less than the maximum
output current capability by a suf?cient margin (10% or
higher is recommended):
V IN(MIN)
V OUT
The inductor ripple current Δ I SW has a direct effect on the
choice of the inductor value and the converter’s maximum
output current capability. Choosing smaller values of
Δ I SW increases output current capability, but requires
large inductances and reduces the current loop gain (the
converter will approach voltage mode). Accepting larger
values of Δ I SW provides fast transient response and
allows the use of low inductances, but results in higher
input current ripple and greater core losses, and reduces
output current capability. It is recommended to choose a
Δ I SW lower than 0.6A.
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:
For a boost converter operating in CCM, the duty cycle
of the main switch can be calculated based on the output
voltage (V OUT ) and the input voltage (V IN ). The maximum
L =
V IN(MIN)
Δ I SW ? ?
? D MAX
V OUT ? V IN(MIN)
V OUT
I L(MAX) = I O(MAX) ?
duty cycle (D MAX ) occurs when the converter has the
minimum input voltage:
D MAX =
Discontinuous conduction mode (DCM) provides higher
conversion ratios at a given frequency at the cost of reduced
ef?ciencies and higher switching currents.
Boost Converter: Maximum Output Current Capability
and Inductor Selection
For the boost topology, the maximum average inductor
current is:
1
1 ? D MAX
Due to the current limit of its internal power switch, the
The peak inductor current is the switch current limit (typical
4A), and the RMS inductor current is approximately equal
to I L(MAX) . The user should choose the inductors having
suf?cient saturation and RMS current ratings.
Boost Converter: Output Diode Selection
To maximize ef?ciency, 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.
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 suf?cient).
LT3958 should be used in a boost converter whose maxi-
3958f
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3958EUHETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Converter |
| LT3958IUHE#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:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3958IUHE#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:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3958IUHEPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Converter |
| LT3958IUHETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Converter |
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