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參數(shù)資料
| 型號： | TPS61251DSGT |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, 3500 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 2 X 2 MM, PLASTIC, WSON-8 |
| 文件頁數(shù)： | 6/23頁 |
| 文件大?。?/td> | 587K |
| 代理商： | TPS61251DSGT |
IN(min)
L(max)
LIM
L
LIM
OUT
V
D
V
I
with D
1
L f
V
h
=
+ D
=
+
=
-
g
PULSE
STANDBY
on
RIPPLE(mV)
OUT
I
t
V
=
C
-
g
(
)
ESR
PULSE
STANDBY
V
= I
I
ESR
D
-
g
SLVSAF7 – SEPTEMBER 2010
www.ti.com
(7)
Regarding the example from above the current ripple (
ΔIL) will be 290 mA and therefore an inductor with a rated
current of about 800 mA should be used.
The TPS61251 is designed to work with inductor values between 1.0 H and 2.2 H. For typical applications a
1.5 H inductor is recommended. Regarding the conversion factor and the need of a sufficient output current the
rated current for the inductor drives into lower inductance values. Therefore the inductor value can be reduced
down to 1.0 H without degrading the stability. Reduced inductance values increase the current ripple that needs
to be included in the peak current calculation for the inductor (Equation 7). Using standard boost converters the
current through the inductor is defined by the switch current limit of the converters switches and therefore bigger
inductors have to be chosen. TPS61251 allows the design engineer to reduce the current limit to the needs of
the application regardless the maximum switch current limit of the converter. Programming a lower current value
allows the use of smaller inductors without the danger to get into saturation.
OUTPUT CAPACITOR
The second energy storing device is the output capacitor. When selecting output capacitors for large pulsed
loads, the magnitude and duration of the pulsing current, together with the ripple voltage specification, determine
the choice of the output capacitor. Both the ESR of the capacitor and the charge stored in the capacitor each
cycle contribute to the output voltage ripple. The ripple due to the charge is approximately what results from
(8)
where IPULSE and tON are the peak current and on time during transmission burst and ISTANDBY is the current in
standby mode. The above is a worst-case approximation assuming all the pulsing energy comes from the output
capacitor.
The ripple due to the capacitor ESR is defined by Equation 9
(9)
High capacitance values and low ESR can lead to instability in some internally compensated boost converters.
The internal loop compensation of the TPS61251 is optimized to be stable with output capacitor values greater
than 150mF with very low ESR.
Since big bulk capacitors can not be placed very close to the IC it is required to put a small ceramic capacitor of
about 4.7 F as close as possible to the output terminals. This will reduce parasitic effects that can influence the
functionality of the converter.
Table 2. List of Bulk Capacitors
VENDOR (alphabetical order)
CAPACITANCE
PART NUMBER
Kemet
470 F, 6.3 V, 55 m
Ω
T520W477M006ATE055
Sanyo
470 F, 6.3 V, 35 m
Ω
6TPE470MAZU
14
Copyright 2010, Texas Instruments Incorporated
Product Folder Link(s): TPS61251
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPS61251DSGT | 制造商:Texas Instruments 功能描述:IC BOOST DC/DC CONV ADJ 3V-6.5V OUTPUT 制造商:Texas Instruments 功能描述:IC, BOOST DC/DC CONV, ADJ 3V-6.5V OUTPUT, 1.5A, 8-QFN |
| TPS61251EVM-517 | 功能描述:電源管理IC開發(fā)工具 TPS61251 Eval Mod RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| TPS61252 | 制造商:TAOS 制造商全稱:TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS 功能描述:TINY 1.5-A BOOST CONVERTER WITH ADJUSTABLE INPUT CURRENT LIMIT |
| TPS61252DSGR | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3.5MHz1.5A92% Eff Boost Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| TPS61252DSGT | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3.5MHz1.5A92% Eff Boost Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
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