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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)： | 4/16頁 |
| 文件大?。?/td> | 185K |
| 代理商： | LTC3873EDDB#TRM |
LTC3873
12
3873fa
APPLICATIONS INFORMATION
In a yback converter, the input ows in pulses placing
severe demands on the input capacitors. Select an input
capacitor with a ripple current rating greater than:
I
P
V
D
RMS
IN
IN MIN
MAX
=
()
–
1
Duty Cycle Considerations
The LTC3873 imposes a maximum duty cycle limit of
80% typical. For a yback converter, the maximum duty
cycle prevents the transformer core from saturation. In
a boost converter application, however, it sets a limit on
the maximum step-up ratio or maximum output voltage
with the given input voltage of:
V
OUT MAX
IN MIN
D
()
–.
–
=
10 8
Current and voltage stress on the power switch and
synchronous rectiers, input and output capacitor RMS
currents and transformer utilization (size vs power) are
impacted by duty factor. Unfortunately duty factor can-
not be adjusted to simultaneously optimize all of these
requirements. In general, avoid extreme duty factors since
this severely impacts the current stress on most of the
components. A reasonable target for duty factor is 50% at
nominal input voltage. Using this rule of thumb, the ideal
transformer turns ratio is:
N
V
D
V
IDEAL
OUT
IN
OUT
IN
==
–
1
Output Diode Selection
To maximize efciency, a fast switching diode with low
forward drop and low reverse leakage is desired. The output
diode in a boost converter conducts current during the
switch off-time. The peak reverse voltage that the diode
must withstand is equal to the regulator output voltage.
The average forward current in normal operation is equal
to the output current, and the peak current is equal to the
peak inductor current.
ITH
NGATE
LTC3873
GND
RUN/SS
VFB = 1.2V
100μF
6.3V
3
0.1μF
Q1
FAN2512
VOUT*
3.3V
3A
VIN
36V TO 72V
4.7μF
100V
221k
4.7μF
10V
68mΩ
*FOR 5V OUTPUT CHANGE RFB TO 42.2k
15k
2.2nF
0.1μF
T1
D2
UPS840
D1
BAS516
3873 F07
VCC
SW
IPRG
12.06k
VOUT
RFB*
21.5k
51Ω
Figure 7. 3.3V Output Nonisolated Telecom DC/DC Converter
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相關代理商/技術參數(shù) |
參數(shù)描述 |
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| 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 |
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