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參數(shù)資料
| 型號(hào)： | TPS54320RHLR |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING REGULATOR, 1320 kHz SWITCHING FREQ-MAX, PQCC14 |
| 封裝： | 3.50 X 3.50 MM, GREEN, PLASTIC, QFN-14 |
| 文件頁數(shù)： | 16/39頁 |
| 文件大?。?/td> | 1358K |
| 代理商： | TPS54320RHLR |
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1
8
f
>
×
Co
Voripple
sw
Iripple
<
Voripple
Resr
Iripple
(
)
(
)
Ceff
Vrating
C
Vrating - Vout
=
(
)
12
f
×
-
=
×
Vout
Vinmax
Vout
Icorms
Vinmax L1
sw
(
)
-
=
×
Vinmin Vout
Vout
Icirms
Iout
Vinmin
0.25
f
×
D
=
×
Ioutmax
Vin
Cin
sw
www.ti.com
SLVS982A – AUGUST 2010 – REVISED SEPTEMBER 2010
Equation 23 calculates the minimum output capacitance needed to meet the output voltage ripple specification.
Where fsw is the switching frequency, Voripple is the maximum allowable output voltage ripple, and Iripple is the
inductor ripple current. In this case, the maximum output voltage ripple is 33mV. Under this requirement,
Equation 23 yields 6.4F.
(23)
Equation 24 calculates the maximum ESR an output capacitor can have to meet the output voltage ripple
specification. Equation 24 indicates the ESR should be less than 40m
Ω. In this case, the ESR of the ceramic
capacitor is much smaller than 40m
Ω.
(24)
The capacitance of ceramic capacitors is highly dependent on the DC output voltage. Equation 25 is used to
select output capacitors based on their voltage rating. For 6.3V ceramic capacitors, the minimum capacitance
that meets the load step specification is 49.7F. For this example, one 47mF, 6.3V, X5R ceramic capacitor with
4m
Ω of ESR is used.
(25)
Capacitors generally have limits to the amount of ripple current they can handle without failing or producing
excess heat. An output capacitor that can support the inductor ripple current must be specified. Some capacitor
data sheets specify the RMS (Root Mean Square) value of the maximum ripple current. Equation 26 can be used
to calculate the RMS ripple current the output capacitor needs to support. For this application, Equation 26 yields
235mA.
(26)
Input Capacitor Selection
The TPS54320 requires a high quality ceramic, type X5R or X7R, input decoupling capacitor of 4.7F on each
input voltage rail. In some applications additional bulk capacitance may also be required for the PVIN input. The
voltage rating of the input capacitor must be greater than the maximum input voltage. The capacitor must also
have a ripple current rating greater than the maximum input current ripple of the TPS54320. The input ripple
current for this design, using Equation 27, is 1.48A.
(27)
The value of a ceramic capacitor varies significantly over both temperature and the amount of DC bias applied to
the capacitor. The capacitance variations due to temperature can be minimized by selecting a dielectric material
that is stable over temperature. X5R and X7R ceramic dielectrics are usually selected for power regulator
capacitors because of the high capacitance to volume ratio and stablity over temperature. The capacitance value
of a capacitor decreases as the DC bias across it increases. For this example design, a ceramic capacitor with at
least a 25V voltage rating is required to support the maximum input voltage. For this example, two 4.7F 25V
capacitors will be used in parallel as the VIN and PVIN inputs are tied together, so the TPS54320 may operate
from a single supply. The input capacitance value determines the input ripple voltage of the regulator. The input
voltage ripple can be calculated using Equation 28. Using the design example values, Ioutmax = 3A, CIN = 9.4mF,
Fsw = 480kHz, Equation 28 yields an input voltage ripple of 166mV.
(28)
Copyright 2010, Texas Instruments Incorporated
23
Product Folder Link(s) :TPS54320
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| TPS54320RHLT | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 4.5-17V Inp3A Sync Step Down Cnvrtr 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 |
| TPS54320RHLT | 制造商:Texas Instruments 功能描述:IC SYNC STEP-DOWN CONTROLLER 1.2MHZ Q 制造商:Texas Instruments 功能描述:IC, SYNC STEP-DOWN CONTROLLER, 1.2MHZ, QFN-14 |
| TPS54325 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:4.5-V to 18-V, 3-A OUTPUT SYNCHRONOUS STEP DOWN SWITCHER WITH INTEGRATED FET (SWIFT?) |
| TPS54325_10 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:4.5-V to 18-V, 3-A OUTPUT SYNCHRONOUS STEP DOWN SWITCHER WITH INTEGRATED FET (SWIFT?) |
| TPS54325EVM | 功能描述:電源管理IC開發(fā)工具 5-17V Input 3A SWIFT CVTR Eval RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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