參數(shù)資料
型號: LT3757HMSE#TRPBF
廠商: LINEAR TECHNOLOGY CORP
元件分類: 穩(wěn)壓器
英文描述: SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO10
封裝: 3 X 3 MM, LEAD FREE, PLASTIC, MSOP-10
文件頁數(shù): 14/36頁
文件大?。?/td> 436K
代理商: LT3757HMSE#TRPBF
LT3757
21
3757fc
applicaTions inForMaTion
Flyback Converter: Output Diode Selection
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 VRRM using:
VRRM >
NS
NP
VIN(MAX) + VOUT
The power dissipated by the diode is:
PD = IO(MAX) VD
and the diode junction temperature is:
TJ = TA + PD RθJA
The RθJA to be used in this equation normally includes the
RθJC for the device, plus the thermal resistance from the
boardtotheambienttemperatureintheenclosure.TJmust
notexceedthediodemaximumjunctiontemperaturerating.
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 COUT and ESRCOUT.
The RMS ripple current rating of the output capacitors
in discontinuous operation can be determined using the
following equation:
IRMS(COUT),DISCONTINUOUS ≥ IO(MAX)
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:
IRMS(CIN),DISCONTINUOUS
POUT(MAX)
VIN(MIN) η
4
(3 DMAX)
3 DMAX
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:
VOUT + VD
VIN
=
D
1
D
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 (CIN,
CDC and COUT), 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
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT3757IDD 制造商:LINER 制造商全稱:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Controller
LT3757IDD#PBF 功能描述:IC REG CTRLR BST FLYBK INV 10DFN RoHS:是 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:2,000 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:50% 電源電壓:9 V ~ 10 V 降壓:無 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:8-TSSOP(0.173",4.40mm 寬) 包裝:帶卷 (TR)
LT3757IDD#PBF 制造商:Linear Technology 功能描述:DC-DC CONTROLLER SEPIC 1MHZ 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, SEPIC, 1MHZ, DFN-10
LT3757IDD#TRPBF 功能描述:IC REG CTRLR BST FLYBK INV 10DFN RoHS:是 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)
LT3757IDDPBF 制造商:Linear Technology 功能描述:Boost Flyback SEPIC Controller DFN10EP