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參數(shù)資料
| 型號： | LT3570IFE#TRPBF |
| 廠商： | Linear Technology |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 288K |
| 描述： | IC REG BUCK/BST/LINEAR 20TSSOP |
| 標(biāo)準(zhǔn)包裝： | 2,500 |
| 拓?fù)洌?/td> | 降壓（降壓）（1），升壓（升壓）（1），線性（LDO）（1） |
| 功能： | 車載 |
| 輸出數(shù)： | 3 |
| 頻率 - 開關(guān)： | 500kHz ~ 2.1MHz |
| 電壓/電流 - 輸出 1： | 可調(diào)至0.8V，1.5A |
| 電壓/電流 - 輸出 2： | 可調(diào)至0.8V，1.5A |
| 電壓/電流 - 輸出 3： | 控制器 |
| 帶 LED 驅(qū)動器： | 無 |
| 帶監(jiān)控器： | 無 |
| 帶序列發(fā)生器： | 無 |
| 電源電壓： | 2.5 V ~ 36 V |
| 工作溫度： | -40°C ~ 125°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 20-TSSOP（0.173"，4.40mm 寬）裸露焊盤 |
| 供應(yīng)商設(shè)備封裝： | 20-TSSOP-EP |
| 包裝： | 帶卷 (TR) |
LT3570
12
3570fb
and small circuit size, are therefore an option. You can
estimate output ripple with the following equations:
V
RIPPLE
=
擨
L2
8"f"C
OUT
for ceramic capacitors
and
V
RIPPLE
= 擨
L2
" ESR for electrolytic capacitors (tantalum
and aluminum)
The RMS content of this ripple is very low so the RMS
current rating of the output capacitor is usually not of
concern. It can be estimated with the formula:
I
C(RMS)
=
擨
L2
12
Another constraint on the output capacitor is that it must
have greater energy storage than the inductor; if the stored
energy in the inductor transfers to the output, the resulting
voltage step should be small compared to the regulation
voltage. For a 5% overshoot, this requirement indicates:
C
OUT
>10"L"
I
LIM2
V
OUT2
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
2
The low ESR and small size of ceramic capacitors make
them the preferred type for LT3570 applications. Not all
ceramic capacitors are the same, however. Many of the
higher value capacitors use poor dielectrics with high
temperature and voltage coef cients. In particular, Y5V
and Z5U types lose a large fraction of their capacitance
with applied voltage and at temperature extremes. Because
loop stability and transient response depend on the value
of C
OUT
, this loss may be unacceptable. Use X7R and X5R
types.
Electrolytic capacitors are also an option. The ESRs of
most aluminum electrolytic capacitors are too large to
deliver low output ripple. Tantalum, as well as newer,
lower ESR organic electrolytic capacitors intended for
power supply use are suitable. Chose a capacitor with a
low enough ESR for the required output ripple. Because
the volume of the capacitor determines its ESR, both the
size and the value will be larger than a ceramic capacitor
that would give similar ripple performance. One bene t
is that the larger capacitance may give better transient
re sponse for large changes in load current. Table 2 lists
several capacitor vendors.
Table 2. Low ESR Surface Mount Capacitors
VENDOR
TYPE
SERIES
Taiyo Yuden
Ceramic
X5R, X7R
AVX
Ceramic
Tantalum
X5R, X7R
TPS
Kemet
Tantalum
Ta Organic
Al Organic
T491, T494, T495
T520
A700
Sanyo
Ta or Al Organic POSCAP
Panasonic
Al Organic
SP CAP
TDK
Ceramic
X5R, X7R
Boost Output Capacitor Selection
Low ESR capacitors should be used at the output to
minimize the output ripple voltage. Multilayer ceramic
capacitors are the best choice, as they have a very low
ESR and are available in very small packages. Always use
a capacitor with a suf cient voltage rating. Boost regula-
tors have large RMS ripple current in the output capacitor,
which must be rated to handle the current. The formula
to calculate this is:
I
RIPPLE(RMS)
=I
OUT
DC1
1DC1
=I
OUT1
V
OUT1
V
IN1
V
IN1
and is largest when V
IN1
is at its minimum value if V
OUT1
and I
OUT1
are constant. With a 1.5A current limit, the
maximum that the output current ripple can be is ~0.75A.
Table 2 lists several capacitor vendors.
Buck Input Capacitor Selection
Bypass the input of the LT3570 circuit with a 10糉 or
higher ceramic capacitor of X7R or X5R type. A lower
value or a less expensive Y5V type will work if there is
additional bypassing provided by bulk electrolytic capaci-
tors, or if the input source impedance is low. The following
paragraphs describe the input capacitor considerations
in more detail.
Step-down regulators draw current from the input supply
in pulses with very fast rise and fall times. The input ca-
pacitor is required to reduce the resulting voltage ripple
at the LT3570 input and to force this switching current
APPLICATIONS INFORMATION
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT3570IUF#PBF | 功能描述:IC REG TRPL BCK/BST/LINEAR 24QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 + 切換式 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 拓?fù)?降壓（降壓）同步（3），線性（LDO）（2） 功能:任何功能 輸出數(shù):5 頻率 - 開關(guān):300kHz 電壓/電流 - 輸出 1:控制器 電壓/電流 - 輸出 2:控制器 電壓/電流 - 輸出 3:控制器 帶 LED 驅(qū)動器:無 帶監(jiān)控器:無 帶序列發(fā)生器:是 電源電壓:5.6 V ~ 24 V 工作溫度:-40°C ~ 85°C 安裝類型:* 封裝/外殼:* 供應(yīng)商設(shè)備封裝:* 包裝:* |
| LT3570IUF#TRPBF | 功能描述:IC REG TRPL BCK/BST/LINEAR 24QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 + 切換式 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 拓?fù)?降壓（降壓）同步（3），線性（LDO）（2） 功能:任何功能 輸出數(shù):5 頻率 - 開關(guān):300kHz 電壓/電流 - 輸出 1:控制器 電壓/電流 - 輸出 2:控制器 電壓/電流 - 輸出 3:控制器 帶 LED 驅(qū)動器:無 帶監(jiān)控器:無 帶序列發(fā)生器:是 電源電壓:5.6 V ~ 24 V 工作溫度:-40°C ~ 85°C 安裝類型:* 封裝/外殼:* 供應(yīng)商設(shè)備封裝:* 包裝:* |
| LT3570IUF-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.5A Buck Converter, 1.5A Boost Converter and LDO Controller |
| LT3570IUF-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:1.5A Buck Converter, 1.5A Boost Converter and LDO Controller |
| LT3571EUD#PBF | 功能描述:IC REG BOOST ADJ 0.47A 16QFN 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:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 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:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
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