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| 型号： | LM3686TLE-AAED/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 13/27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
Operation Description
DEVICE INFORMATION
The LM3686 incorporates a high efficiency synchronous switching step-down DC-DC converter, a very low
dropout linear regulator (LILO), and ultra low noise linear regulator.
The DC-DC converter delivers a constant voltage from a single Li- Ion battery and input voltage rails from 2.7V to
5.5V to portable devices such as cell phones and PDAs. Using a voltage mode architecture with synchronous
rectification, it has the ability to deliver up to 600 mA load current (when not powering the LILO) depending on
the input voltage, output voltage, ambient temperature and the inductor chosen.
The linear regulator delivers a constant voltage biased from V IN_LILO power input typically the output voltage of
the DC-DC converter is used (post regulation) with a maximum load current of 350 mA.
The other linear regulator delivers a constant voltage biased from V IN_LDO power input - with a maximum load
current of 300 mA.
Three enable pins allow the independent control of the three outputs. Shutdown mode turns off the device,
offering the lowest current consumption (I SHUTDOWN = 2.5 μA typ).
Besides the shutdown feature, for the DC-DC converter there are two more modes of operation depending on the
current required:
- PWM (Pulse Width Modulation), and
- PFM (Pulse Frequency Modulation).
The device operates in PWM mode at load current of approximately 80 mA or higher. Lighter load current cause
the device to automatically switch into PFM for reduced current consumption (I Q_VBATT = 28 μA typ) and a longer
battery life.
Additional features include soft-start, startup mode of the linear regulator, under-voltage protection, current
overload protection, and over-temperature protection.
An internal reference generates a 1.8V biasing an internal resistive divider to create a reference voltage range
from 0.7V to 1.8V (in 50 mV steps) for the LILO and the 0.5V reference used for the DC-DC converter. The ultra
low noise linear regulator also has internal reference that generates a 1.8V biasing for a internal resistor divider.
Thus, creating a reference voltage ranging from 1.5V to 3.3V
The Under-voltage lockout feature enables the device to startup once V BATT has reached 2.65V typically and
turns the device off if V BATT drops below 2.41V typically.
Post Regulation Note:
In the case that the DC-DC converter is switched off while the Linear Regulator is still enabled, the LILO can still
support up to 50 mA. The linear regulator LILO is turned on via a small NMOS device supplied by V IN_LDO . The
maximum current is 50 mA when this small NMOS is ON. If higher current > 50 mA is desired the following
condition must be done:
1) EN_DC = HIGH
When the condition is met, the LILO transitions to the large NMOS and can support up to 350 mA.
DC-DC CONVERTER OPERATION
During the first part of each switching cycle, the control block in the LM3686 turns on the internal PFET switch.
This allows current to flow from the input V BATT through the switch pin SW and the inductor to the output filter
capacitor and load. The inductor limits the current to a ramp with a slope of (V BATT - V OUT_DCDC ) / L, by storing
energy in the magnetic field.
During the second part of each cycle, the controller turns the PFET switch off, blocking current flow from the
input, and then turns the NFET synchronous rectifier on. The inductor draws current from ground through the
NFET to the output filter capacitor and load, which ramps the inductor current down with a slope of (- V OUT_DCDC /
L).
The output filter stores charge when the inductor current is high, and releases it when low, smoothing the voltage
across the load.
Copyright ? 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM3686
13
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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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