- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄44994 > LTC3873EDDB#TRM (LINEAR TECHNOLOGY CORP) SWITCHING CONTROLLER, 240 kHz SWITCHING FREQ-MAX, PDSO8 PDF資料下載
參數(shù)資料
| 型號： | LTC3873EDDB#TRM |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 240 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 3 X 2 MM, 0.75 MM HEIGHT, PLASTIC, MO-229WECD-1, DFN-8 |
| 文件頁數(shù)： | 3/16頁 |
| 文件大?。?/td> | 185K |
| 代理商： | LTC3873EDDB#TRM |
LTC3873
11
3873fa
plus the secondary-to-primary referred voltage of the
yback pulse (including leakage spike) must not exceed
the allowed external MOSFET breakdown rating.
Leakage Inductance
Transformer leakage inductance (on either the primary
or secondary) causes a voltage spike to occur after the
output switch (Q1) turn-off. This is increasingly prominent
at higher load currents where more stored energy must
be dissipated. In some cases a “snubber” circuit will be
required to avoid overvoltage breakdown at the MOSFET’s
drain node. Application Note 19 is a good reference on
snubber design. A bilar or similar winding technique is a
good way to minimize troublesome leakage inductances.
However, remember that this will limit the primary-to-
secondary breakdown voltage, so bilar winding is not
always practical.
Power MOSFET Selection
The power MOSFET serves two purposes in the LTC3873:
it represents the main switching element in the power path
and its RDS(ON) represents the current sensing element
for the control loop. Important parameters for the power
MOSFET include the drain-to-source breakdown voltage
(BVDSS), the threshold voltage (VGS(TH)), the on-resistance
(RDS(ON))versusgate-to-sourcevoltage,thegate-to-source
and gate-to-drain charges (QGS and QGD, respectively),
the maximum drain current (ID(MAX)) and the MOSFET’s
thermal resistances (RTH(JC) and RTH(JA)).
For boost applications with RDS(ON) sensing, refer to
the LTC3872 data sheet for the selection of MOSFET
RDS(ON).
MOSFETs have conduction losses (I2R) and switching
losses. For VDS < 20V, high current efciency generally
improves with large MOSFETs with low RDS(ON), while
for VDS > 20V the transition losses rapidly increase to the
point that the use of a higher RDS(ON) device with lower
reverse transfer capacitance, CRSS, actually provides
higher efciency.
Output Capacitors
The output capacitor is normally chosen by its effective
series resistance (ESR), which determines output ripple
voltage and affects efciency. Low ESR ceramic capaci-
tors are often used to minimize the output ripple. Boost
regulators have large RMS ripple current in the output
capacitor that must be rated to handle the current. The
output ripple current (RMS) is:
II
VV
V
RMS COUT
OUT MAX
OUT
IN MIN
()
(
)
()
–
≈
Output ripple is then simply:
VOUT = RESR(ΔIL(RMS))
The output capacitor for yback converter should have a
ripple current rating greater than:
II
D
RMS
OUT
MAX
=
–
1
Input Capacitors
The input capacitor of a boost converter is less critical due
to the fact that the input current waveform is triangular, and
does not contain large square wave currents as found in
the output capacitor. The input voltage source impedance
determines the size of the capacitor that is typically 10μF to
100μF. A low ESR is recommended although not as critical
as the output capacitor can be on the order of 0.3
Ω.
The RMS input ripple current for a boost converter is:
I
V
Lf
D
RMS CIN
IN MIN
MAX
()
.
= 03
Please note that the input capacitor can see a very high
surge current when a battery is suddenly connected to the
input of the converter and solid tantalum capacitors can
fail catastrophically under these conditions.
APPLICATIONS INFORMATION
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC3878EGN#PBF | SWITCHING CONTROLLER, PDSO16 |
| LTC3878IGN#PBF | SWITCHING CONTROLLER, PDSO16 |
| LTC3878IGN#TRPBF | SWITCHING CONTROLLER, PDSO16 |
| LTC3879EUD#TRPBF | SWITCHING CONTROLLER, PQCC16 |
| LTC3879IUD#PBF | SWITCHING CONTROLLER, PQCC16 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3873ETS8#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Up 8.8V to 75V Input 8-Pin TSOT-23 |
| LTC3873ETS8#TRMPBF | 功能描述:IC REG CTRLR BST FLYBK TSOT23-8 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝: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) |
| LTC3873ETS8#TRPBF | 功能描述:IC REG CTRLR BST FLYBK TSOT23-8 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝: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) |
| LTC3873ETS8-5#PBF | 制造商:Linear Technology 功能描述:DP-SWREG/Isolated, CUT TAPE No Rsense Constant Frequency Current Mode Boost/Flyb |
| LTC3873ETS8-5#TRM | 制造商:Linear Technology 功能描述: |
發(fā)布緊急采購，3分鐘左右您將得到回復。