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| 型号： | LM3686TLE-AAED/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 17/27页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC .9A TRPL 12USMD |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 固定 |
| 输出数： | 3 |
| 输出电压： | 1.2V，1.8V，2.8V |
| 输入电压： | 2.7 V ~ 5.5 V |
| PWM 型： | 电流/电压模式 |
| 频率 - 开关： | 3MHz |
| 电流 - 输出： | 900mA |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 12-WFBGA |
| 包装： | 标准包装 |
| 供应商设备封装： | 12-uSMD |
| 产品目录页面： | 1288 (CN2011-ZH PDF) |
| 其它名称： | LM3686TLE-AAED/NOPBDKR LM3686TLE-AAEDDKR LM3686TLE-AAEDDKR-ND |
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SNVS520E – AUGUST 2008 – REVISED MAY 2013
APPLICATION INFORMATION
Application Selection
It is strongly recommended to select the required components of LM3686 as described within the datasheet. If
other components are selected, the device will not perform up to standard and electrical characteristics cannot
be ensured.
Inductor Selection
There are two main considerations when choosing an inductor; the inductor should not saturate, and the inductor
current ripple should be small enough to achieve the desired output voltage ripple. Different saturation current
rating specifications are followed by different manufacturers so attention must be given to details. Saturation
current ratings are typically specified at 25°C. However, ratings at the maximum ambient temperature of
application should be requested from the manufacturer. The minimum value of inductance to ensure good
performance is 0.7 μH at I LIM (typ) dc current over the ambient temperature range. Shielded inductors
radiate less noise and should be preferred. There are two methods to choose the inductor saturation current
rating.
METHOD 1
The saturation current should be greater than the sum of the maximum load current and the worst case average
to peak inductor current. This can be written as:
I SAT > I OUT_DCDC_MAX + I RIPPLE
where
I SAT ! I OUTMAX + I RIPPLE
(1)
? ¨ V BATT ? ¨ f ?
where I RIPPLE =
¨
§ V BATT - V OUT · x § V OUT · x § 1 ·
? 2 x L 1 ? 1 ? 1
?
?
?
?
I RIPPLE : average to peak inductor current
I OUT_DCDCMAX : maximum load current (600 mA)
V BATT : maximum input voltage in application
L: minimum inductor value including worst case tolerances (30% drop can be considered for method 1)
?
f: minimum switching frequency (2.55 MHz)
(2)
METHOD 2
A more conservative and recommended approach is to choose an inductor that has a saturation current rating
greater than the maximum current limit of 1375 mA.
A 1.0 μH inductor with a saturation current rating of at least 1375 mA is recommended for most applications. The
inductor’s resistance should be less than 0.3 ? for good efficiency. Table 1 lists suggested inductors and
suppliers. For low-cost applications, an unshielded bobbin inductor could be considered. For noise critical
applications, a toroidal or shielded- bobbin inductor should be used. A good practice is to lay out the board with
overlapping footprints of both types for design flexibility. This allows substitution of a low-noise shielded inductor,
in the event that noise from low-cost bobbin models is unacceptable.
Table 1. Suggested Inductors and their Suppliers
Model
BRL2518T1R0M
MDT2520CR1R0M
KSLI252010AG1R0
Vendor
TAIYO YUDEN
TOKO
HITACHI METALS
Dimensions LxWxH (mm)
2.5 X 1.8 X 1.2
2.5 X 2.0 X 1.0
2.5 X 2.0 X 1.0
DCR (max)
80
80
75
External Capacitors
As common with most regulators, the LM3686 requires external capacitors to ensure stable operation. The
LM3686 is specifically designed for portable applications requiring minimum board space and the smallest size
components. These capacitors must be correctly selected for good performance.
Copyright ? 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM3686
17
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3686TLE-AAEF | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Step-Down DC-DC Converter with Integrated Post Linear Regulators System and Low-Noise Linear Regulator |
| LM3686TLE-AAEF/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM3686TLX-AADW | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Step-Down DC-DC Converter with Integrated Post Linear Regulators System and Low-Noise Linear Regulator |
| LM3686TLX-AADW/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM3686TLX-AAED | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Step-Down DC-DC Converter with Integrated Post Linear Regulators System and Low-Noise Linear Regulator |
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