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參數(shù)資料
| 型號： | LTC3542IS6#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | LEAD FREE, PLASTIC, MO-193, TSOT-23, 6 PIN |
| 文件頁數(shù)： | 4/16頁 |
| 文件大?。?/td> | 211K |
| 代理商： | LTC3542IS6#PBF |
LTC3542
12
3542fa
parallel with COUT, causing a rapid drop in VOUT. No regula-
tor can deliver enough current to prevent this problem, if
the switch connecting the load has low resistance and is
driven quickly. The solution is to limit the turn-on speed of
the load switch driver. A Hot SwapTM controller is designed
specically for this purpose and usually incorporates cur-
rent limit, short circuit protection and soft-start.
Design Example
As a design example, assume the LTC3542 is used in a single
lithium-ion battery-powered cellular phone application. The
VIN will be operating from a maximum of 4.2V down to
about 2.7V. The load current requirement is a maximum
of 0.5A, but most of the time it will be in standby mode,
requiring only 2mA. Efciency at both low and high load
currents is important. Output voltage is 1.8V.
With this information we can calculate L using:
L
fI
V
L
OUT
IN
=
1
–
Δ
Substituting VOUT = 1.8V, VIN = 4.2V, ΔIL = 200mA and
f = 2.25MHz gives:
L
V
MHz
mA
V
μH
=
=
18
2 25
200
1
18
42
228
.
–
.
Choosing a vendor’s closest inductor value of 2.2μH results
in a maximum ripple current of:
ΔI
V
MHz
μH
V
L =
=
18
225
2 2
1
18
42
207
.
. .
–
.
.8
8mA
Hot Swap is a trademark of Linear Technology Corporation.
CIN will require an RMS current rating of at least
0.25A
ILOAD(MAX)/2 at temperature and COUT will require
ESR of less than 0.2
Ω. In most cases, ceramic capacitors
will satisfy these requirements. Select COUT = 10μF and
CIN = 10μF.
For the feedback resistors, choose R1 = 75k, R2 can be
calculated from:
R
V
R
V
k
OUT
2
06
11
18
06
175
=
=
.
–
.
–
== 150k
Figure 3 shows the complete circuit along with its efciency
curve, load step response and recommended layout
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of
the LTC3542. These items are also illustrated graphically
in Figure 3b. Check the following in your layout:
1. The power traces, consisting of the GND trace, the SW
trace and the VIN trace should be kept short, direct and
wide.
2. Does the VFB pin connect directly to the feedback re-
sistors? The resistive divider R1/R2 must be connected
between the (+) plate of COUT and ground.
3. Does the (+) plate of CIN connect to VIN as closely as
possible? This capacitor provides the AC current to the
internal power MOSFETs.
4. Keep the (–) plates of CIN and COUT as close as pos-
sible.
5. Keep the switching node, SW, away from the sensitive
VFB node.
APPLICATIONS INFORMATION
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| LTC3542IS6-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:500mA, 2.25MHz Synchronous Step-Down DC/DC Converter |
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| LTC3543EDCB#TRMPBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 8DFN 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: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(guān):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(yīng)商設(shè)備封裝:8-SOIC |
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