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參數(shù)資料
| 型號： | LT3957IUHE#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, PQCC36 |
| 封裝： | 5 X 6 MM, LEAD FREE, PLASTIC, QFN-36 |
| 文件頁數(shù)： | 10/28頁 |
| 文件大?。?/td> | 359K |
| 代理商： | LT3957IUHE#PBF |
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LT3957
18
3957f
APPLICATIONS INFORMATION
In some cases a snubber circuit will be required to avoid
overvoltage breakdown at the MOSFET’s drain node. There
are different snubber circuits (such as RC snubber, RCD
snubber, Zener clamp, etc.), and Application Note 19 is a
good reference on snubber design. An RC snubber circuit
can be connected between SW and GND to damp the
ringing on SW pins. The snubber resistor values should
be close to the impedance of the parasitic resonance. The
snubber capacitor value should be larger than the circuit
parasitic capacitance, but be small enough to keep the
snubber resistor power dissipation low.
If the RC snubber is insufcient to prevent SW pins over-
voltage, the RCD snubber can be used to limit the peak
voltage on the SW pins, which is shown in Figure 6.
The snubber resistor value (RSN) can be calculated by the
following equation:
RSN = 2
V2SN VSN VOUT
NP
NS
I2SW(PEAK) LLK
LLK is the leakage inductance of the primary winding,
which is usually specied in the transformer character-
istics. LLK can be obtained by measuring the primary
inductance with the secondary windings shorted. The
snubber capacitor value (CSN) can be determined using
the following equation:
CCN =
VSN
ΔVSN RSN
where
ΔVSN is the voltage ripple across CSN. A reasonable
ΔVSN is 5% to 10% of VSN. The reverse voltage rating of
DSN should be higher than the sum of VSN and VIN(MAX).
A Zener clamp can also be connected between SW and
GND to ensure SW voltage does not exceed 40V.
Flyback Converter: Output Diode Selection
The output diode in a yback 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
RθJCforthedevice,plusthethermalresistancefromtheboard
to the ambient temperature in the enclosure. TJ must not
exceed the diode maximum junction temperature rating.
Flyback Converter: Output Capacitor Selection
The output capacitor of the yback 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 continuous operation can be determined using the
following equation:
I≈ IO(MAX)
DMAX
1DMAX
Flyback Converter: Input Capacitor Selection
The input capacitor in a yback 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
continuous operation can be determined using the fol-
lowing equation:
IRMS(CIN),CONTINUOUS ≈
POUT(MAX)
VIN(MIN) η
1DMAX
DMAX
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT3958IUHE#PBF | SWITCHING REGULATOR, PQCC36 |
| LT3958EUHE#PBF | SWITCHING REGULATOR, PQCC36 |
| LT3958EUHE#TRPBF | SWITCHING REGULATOR, PQCC36 |
| LT4180MPGN#PBF | POWER SUPPLY SUPPORT CKT, PDSO24 |
| LT4180IGN#PBF | POWER SUPPLY SUPPORT CKT, PDSO24 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT3957IUHETRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch |
| LT3958 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Monolithic High Voltage Isolated Flyback Converter No External Start-Up Resistor |
| LT3958EUHE#PBF | 功能描述:IC REG MULTI CONFIG ADJ 36VQFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LT3958EUHE#PBF | 制造商:Linear Technology 功能描述:IC BOOST/FLYBACK/SEPIC/INVERT CTRL QFN36 |
| LT3958EUHE#TRPBF | 功能描述:IC REG MULTI CONFIG ADJ 36VQFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
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