参数资料
型号: LT3757IDD#PBF
厂商: Linear Technology
文件页数: 21/36页
文件大小: 0K
描述: IC REG CTRLR BST FLYBK INV 10DFN
产品培训模块: LT3757 and LT3758 - Boost, Flyback, SEPIC and Inverting Controllers
标准包装: 121
PWM 型: 电流模式
输出数: 1
频率 - 最大: 1MHz
电源电压: 2.9 V ~ 40 V
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: -40°C ~ 125°C
封装/外壳: 10-WFDFN 裸露焊盘
包装: 管件
LT3757/LT3757A
APPLICATIONS INFORMATION
V RRM > S ? V IN(MAX) + V OUT
I RMS(CIN),DISCONTINUOUS ≥
P OUT(MAX) 4 ? (3 ? D MAX )
V IN(MIN) ? h
V OUT + V D D
1 ? D
V IN
I RMS(COUT),DISCONTINUOUS ≥ I O(MAX) ?
FlybackConverter:OutputDiodeSelection
The output diode in a flyback converter is subject to large
RMS current and peak reverse voltage stresses. A fast
switching diode with a low forward drop and a low reverse
leakage is desired. Schottky diodes are recommended if
the output voltage is below 100V.
Approximate the required peak repetitive reverse voltage
rating V RRM using:
N
N P
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
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.
Flyback Converter: Output Capacitor Selection
The output capacitor of the flyback converter has a similar
operation condition as that of the boost converter. Refer
to the Boost Converter: Output Capacitor Selection section
for the calculation of C OUT and ESR COUT .
The RMS ripple current rating of the output capacitors
in discontinuous operation can be determined using the
following equation:
4 ? (3 ? D2)
3 ? D2
Flyback Converter: Input Capacitor Selection
The input capacitor in a flyback converter is subject to
a large RMS current due to the discontinuous primary
current. To prevent large voltage transients, use a low
ESR input capacitor sized for the maximum RMS current.
The RMS ripple current rating of the input capacitors in
discontinuous operation can be determined using the
following equation:
?
3 ? D MAX
SEPIC CONVERTER APPLICATIONS
The LT3757 can be configured as a SEPIC (single-ended
primary inductance converter), as shown in Figure 1. This
topology allows for the input to be higher, equal, or lower
than the desired output voltage. The conversion ratio as
a function of duty cycle is:
=
in continuous conduction mode (CCM).
In a SEPIC converter, no DC path exists between the input
and output. This is an advantage over the boost converter
for applications requiring the output to be disconnected
from the input source when the circuit is in shutdown.
Compared to the flyback converter, the SEPIC converter
has the advantage that both the power MOSFET and the
output diode voltages are clamped by the capacitors (C IN ,
C DC and C OUT ), therefore, there is less voltage ringing
across the power MOSFET and the output diodes. The
SEPIC converter requires much smaller input capacitors
than those of the flyback converter. This is due to the fact
that, in the SEPIC converter, the inductor L1 is in series
with the input, and the ripple current flowing through the
input capacitor is continuous.
3757afd
21
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LT3757IDD-TRPBF 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Controller
LT3757IMSE 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Flyback Controller 2.9V to 40V Input 10-Pin MSOP EP 制造商:Linear Technology 功能描述:CONTROLLER
LT3757IMSE#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:- 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)
LT3757IMSE#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)
LT3757IMSEPBF 制造商:Linear Technology 功能描述:Boost Flyback SEPIC Controller MSOP10EP