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參數資料
| 型號： | LT3420 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Photoflash Capacitor Chargers with Automatic Refresh |
| 中文描述： | 照相閃光燈電容充電器，具有自動刷新 |
| 文件頁數： | 11/20頁 |
| 文件大小： | 368K |
| 代理商： | LT3420 |
LT3420/LT3420-1
11
3420fa
must be taken into account for the dynamic blocking
voltage capabilities of the LT3420/LT3420-1. The dynamic
blocking voltage capability of both parts is 38V.
Table 1 summarizes the various breakdown voltages of the
SW pin for both parts.
Table 1. SW Pin Voltage Ratings
PART
SW PIN DC RATING
LT3420
LT3420-1
SW PIN DYNAMIC RATING
38V
38V
38V
50V
Figure 7 shows what to examine in a new transformer
design to determine if the specifications for the SW pin are
met.
The first leakage inductance spike labeled “A” must not
exceed the dynamic rating of the SW pin. If it does exceed
the rating, then the transformer leakage inductance must
be lowered. The flyback waveform after the initial spike
labeled “B” must not exceed the DC rating of the SW pin.
If it does exceed the rating, then the turns ratio of the
transformer must be lowered. In measuring the voltage on
the SW pin, care must be taken in minimizing the ground
loop of the voltage probe. Careless probing will result in
inaccurate readings.
APPLICATIOU
W
U
U
Note also the magnitude of the initial current spike in the
primary of the transformer labeled “C” when the power
switch turns on. If the leakage inductance is lowered to a
very low level, the internal capacitances of the transformer
will be high. This will result in the initial spike of current in
the primary becoming excessively high. The level of “C”
should be kept to 4A or less in a typical design for both the
LT3420 and LT3420-1. Please note that by inserting a loop
of wire in the primary to measure the primary current, the
leakage inductance of the primary will be made artificially
high. This may result in erroneous voltage measurements
on the SW pin.
The measurements shown in Figure 7 should be made
with both V
OUT
and V
BAT
at the maximum levels for the
given application. This results in the highest voltage and
current stress on the SW pin.
Transformer Secondary Capacitance
The total capacitance of the secondary should be mini-
mized for both efficient and proper operation of the LT3420/
LT3420-1. Since the secondary of the transformer under-
goes large voltage swings (approaching 600V
P-P
), any
capacitance on the secondary can severely affect the
I
PRI
V
SW
3420 F07
0A
0V
“A”
“B”
MUST BE LESS THAN 38V
FOR BOTH THE LT3420
AND LT3420-1
MUST BE LESS THAN 4A
FOR BOTH THE LT3420
AND LT3420-1
MUST BE LESS THAN 38V
FOR THE LT3420
MUST BE LESS THAN 50V
“C”
Figure 7. New Transformer Design Check (Not to Scale)
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LT3420-1 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Photoflash Capacitor Chargers with Automatic Refresh |
| LT3420EDD#PBF | 功能描述:IC PHOTOFLASH CAP CHARGER 10-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 電源管理 - 專用 系列:- 標準包裝:1 系列:- 應用:手持/移動設備 電流 - 電源:- 電源電壓:3 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-WFDFN 裸露焊盤 供應商設備封裝:14-LLP-EP（4x4） 包裝:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名稱:LP3905SD-30DKR |
| LT3420EDD#TR | 制造商:Linear Technology 功能描述:SP-SWREG/Monolithic, Photoflash Capacitor Charger w/ Automatic Top-Off |
| LT3420EDD#TRPBF | 功能描述:IC PHOTOFLASH CAP CHARGER 10-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 電源管理 - 專用 系列:- 應用說明:Ultrasound Imaging Systems Application Note 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:37 系列:- 應用:醫(yī)療用超聲波成像，聲納 電流 - 電源:- 電源電壓:2.37 V ~ 6 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:56-WFQFN 裸露焊盤 供應商設備封裝:56-TQFN-EP（8x8） 包裝:管件 |
| LT3420EDD-1#PBF | 功能描述:IC PHOTOFLASH CAP CHARGER 10-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 電源管理 - 專用 系列:- 標準包裝:1 系列:- 應用:手持/移動設備 電流 - 電源:- 電源電壓:3 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-WFDFN 裸露焊盤 供應商設備封裝:14-LLP-EP（4x4） 包裝:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名稱:LP3905SD-30DKR |
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