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參數(shù)資料
| 型號： | LT3437 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Panels; For Use With:EUROCARD Subracks RoHS Compliant: Yes |
| 中文描述： | 高電壓，200kHz降壓500mA的降壓開關穩(wěn)壓器以100？的靜態(tài)電流 |
| 文件頁數(shù)： | 13/24頁 |
| 文件大?。?/td> | 523K |
| 代理商： | LT3437 |
LT3437
13
3437f
APPLICATIOU
more output current because they reduce peak current
seen by the LT3437 switch, which has a 0.5A limit. Higher
values also reduce output ripple voltage and reduce core
loss.
When choosing an inductor you might have to consider
maximum load current, core and copper losses, allow-
able component height, output voltage ripple, EMI, fault
current in the inductor, saturation and of course cost.
The following procedure is suggested as a way of han-
dling these somewhat complicated and conflicting
requirements.
1. Choose a value in microhenries such that
the maximum
load current plus half of the inductor ripple current is
less than the minimum peak switch current (I
PK
).
Choosing a small inductor with lighter loads may result
in discontinuous mode of operation, but the LT3437 is
designed to work well in either mode.
Assume that the average inductor current is equal to
load current and decide whether or not the inductor
must withstand continuous fault conditions. If maxi-
mum load current is 0.25A, for instance, a 0.25A
inductor may not survive a continuous minimum peak
switch current overload condition.
For applications with a duty cycle above 50%, the
inductor value should be chosen to obtain an inductor
ripple current of less than 40% of the peak switch
current.
2. Calculate peak inductor current at full load current to
ensure that the inductor will not saturate. Peak current
can be significantly higher than output current, especially
with smaller inductors and lighter loads, so do not omit
this step. Powdered iron cores are forgiving because they
saturate softly, whereas ferrite cores saturate abruptly.
Other core materials fall somewhere in between. The
following formula assumes continuous mode of opera-
tion, but it errs only slightly on the high side for discon-
tinuous mode, so it can be used for all conditions.
(
( )( )( )
W
U
U
I
I
V
V
V
f L V
PEAK
OUT
OUT
2
IN
OUT
IN
=
+
)
–
V
IN
= maximum input voltage
f = switching frequency, 200kHz
3. Decide if the design can tolerate an “open” core geom-
etry like a rod or barrel, which has high magnetic field
radiation, or whether it needs a closed core like a toroid,
to prevent EMI problems. This is a tough decision
because the rods or barrels are temptingly cheap and
small, and there are no helpful guidelines to calculate
when the magnetic field radiation will be a problem.
4. After making an initial choice, consider the secondary
things like output voltage ripple, second sourcing, etc.
Use the experts in Linear Technology’s applications
department if you feel uncertain about the final choice.
They have experience with a wide range of inductor
types and can tell you about the latest developments in
low profile, surface mounting, etc.
Table 3. Inductor Selection Criteria
VENDOR/
PART NO.
Coiltronics
UP1B-101
UP1B-151
UP2B-221
Coilcraft
D01605T-473MX
D01605T-104MX
D03308P-154
D03308P-224
Sumida
CDRH4D28-470
CDRH4D28-101
CDRH5D28-101
VALUE
(
μ
H)
I
DC(MAX)
(mA)
DCR
(Ohms)
HEIGHT
(mm)
100
150
220
530
460
380
1.11
1.61
1.96
5.0
5.0
5.0
47
100
150
220
450
300
600
500
1.1
2.3
0.94
1.6
1.8
1.8
3.0
3.0
47
100
100
480
290
420
0.387
1.02
0.520
3.0
3.0
3.0
Short-Circuit Considerations
The LT3437 is a current mode controller. It uses the V
C
node voltage as an input to a current comparator which
turns off the output switch on a cycle-by-cycle basis as
this peak current is reached. The internal clamp on the V
C
node, nominally 1.5V, then acts as an output switch peak
current limit. This action becomes the switch current limit
specification. The maximum available output power is
then determined by the switch current limit.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LT3437_1 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Voltage 500mA, 200kHz Step-Down Switching Regulator with 100μA Quiescent Current |
| LT3437EDD | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 3.3V to 60V 10-Pin DFN EP |
| LT3437EDD#PBF | 功能描述:IC REG BUCK ADJ 0.5A 10DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 設計資源:Design Support Tool 標準包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:100mA 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:SOT-23-5 細型，TSOT-23-5 包裝:剪切帶 (CT) 供應商設備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
| LT3437EDD#TRPBF | 功能描述:IC REG BUCK ADJ 0.5A 10DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關:600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應商設備封裝:8-SOIC |
| LT3437EFE | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 3.3V to 60V 16-Pin TSSOP EP |
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