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參數(shù)資料
| 型號： | LM26480QSQX-CF/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2.4 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, QCC24 |
| 封裝： | 4 X 4 MM, 0.80 MM HEIGHT, ROHS COMPLIANT, LLP-24 |
| 文件頁數(shù)： | 15/30頁 |
| 文件大小： | 2455K |
| 代理商： | LM26480QSQX-CF/NOPB |
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OUTPUT INDUCTORS & CAPACITORS FOR SW1 AND
SW2
There are several design considerations related to the selec-
tion of output inductors and capacitors:
Load transient response;
Stability;
Efficiency;
Output ripple voltage; and
Over-current ruggedness.
The LM26480 has been optimized for use with nominal values
2.2 H and 10 F. If other values are needed for the design,
please contact National Semiconductor sales with any con-
cerns.
INDUCTOR SELECTION FOR SW1 AND SW2
A nominal inductor value of 2.2 H is recommended. It is im-
portant to guarantee the inductor core does not saturate
during any foreseeable operational situation.
Care should be taken when reviewing the different saturation
current ratings that are specified by different manufacturers.
Saturation current ratings are typically specified at 25C, so
ratings at maximum ambient temperature of the application
should be requested from the manufacturer.
There are two methods to choose the inductor saturation cur-
rent rating:
Recommended method:
The best way to guarantee the inductor does not saturate is
to choose an inductor that has saturation current rating
greater than the maximum LM26480 current limit of 2.4A. In
this case the device will prevent inductor saturation.
Alternate method:
If the recommended approach cannot be used, care must be
taken to guarantee that the saturation current is greater than
the peak inductor current:
30040471
I
SAT:
Inductor saturation current at operating tempera-
ture
I
LPEAK:
Peak inductor current during worst case conditions
I
OUTMAX:
Maximum average inductor current
I
RIPPLE:
Peak-to-Peak inductor current
V
OUT:
Output voltage
V
IN:
Input voltage
L:
Inductor value in Henries at I
OUTMAX
F:
Switching frequency, Hertz
D:
Estimated duty factor
EFF:
Estimated power supply efficiency
I
SAT may not be exceeded during any operation, including
transients, startup, high temperature, worst case conditions,
etc.
SUGGESTED INDUCTORS AND THEIR SUPPLIERS
Model
Vendor
Dimensions (mm)
DCR (max)
I
SATURATION
DO3314-222MX
Coilcraft
3.3 x 3.3 x 1.4
200 m
≈1.8A
LPO3310-222MX
Coilcraft
3.3 x 3.3 x 1
150 m
≈1.3A
ELL6PG2R2N
Panasonic
6.0 x 6.0 x 2.0
37 m
≈2.2A
ELC6GN2R2N
Panasonic
6.0 x 6.0 x 1.5
53 m
≈1.9A
CDRH2D14NP-2R2NC
Sumida
3.2 x 3.2 x 1.5
94 m
≈1.5A
Note: Inductor Current Saturation values are estimates; inductor manufacturer should be contacted for guaranteed values.
OUTPUT CAPACITOR SELECTION FOR SW1 AND SW2
A ceramic output capacitor of 10 F, 6.3V is recommended
with an ESR of less than 500 m
.
Output ripple can be estimated from the vector sum of the
reactive (Capacitor) voltage component and the real (ESR)
voltage component of the output capacitor.
V
COUT:
Estimated reactive output ripple
V
ROUT:
Estimated real output ripple
V
PPOUT:
Estimated peak-to-peak output ripple
The output capacitor needs to be mounted as close as pos-
sible to the output pin of the device. For better temperature
performance, X7R or X5R types are recommended. DC bias
characteristics of ceramic capacitors must be considered
when selecting case sizes like 0805 and 0603.
DC bias characteristics vary from manufacturer to manufac-
turer and by case size. DC bias curves should be requested
from them as part of the capacitor selection process. ESR is
typically higher for smaller packages.
The output filter capacitor smooths out current flow from the
inductor to the load, helps maintain a steady output voltage
during transient load changes and reduces output voltage
ripple. These capacitors must be selected with sufficient ca-
pacitance and sufficiently low ESR to perform these functions.
Note that the output voltage ripple is dependent on the induc-
tor current ripple and the equivalent series resistance of the
output capacitor (ESR
COUT). ESRCOUT is frequency depen-
dent as well as temperature dependent. The R
ESR should be
calculated with the applicable switching frequency and ambi-
ent temperature.
www.national.com
22
LM26480
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM26480SQ-AA | 制造商:Texas Instruments 功能描述:DC/ DC STEP DOWN, DUAL LINEAR REG, IC |
| LM26480SQ-AA/NOPB | 功能描述:線性穩(wěn)壓器 - 標準 DUAL HI-CRNT STEP- DOWN DC/DC RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| LM26480SQ-AA/S7002404 | 制造商:Texas Instruments 功能描述: |
| LM26480SQ-AAEV | 功能描述:BOARD EVALUATION LM26480SQ-AA RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - DC/DC 與 AC/DC（離線）SMPS 系列:- 產(chǎn)品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:True Shutdown™ 主要目的:DC/DC，步升 輸出及類型:1，非隔離 功率 - 輸出:- 輸出電壓:- 電流 - 輸出:1A 輸入電壓:2.5 V ~ 5.5 V 穩(wěn)壓器拓撲結構:升壓 頻率 - 開關:3MHz 板類型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| LM26480SQ-AAEV/NOPB | 功能描述:電源管理IC開發(fā)工具 LM26480SQ-AAEV EVAL BOARD 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 |
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