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| 型号： | LM3102EVAL |
| 厂商： | National Semiconductor |
| 文件页数： | 13/24页 |
| 文件大小： | 0K |
| 描述： | BOARD EVALUATION LM3102 |
| 标准包装： | 1 |
| 系列： | PowerWise®, SIMPLE SWITCHER® |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 3.3V |
| 电流 - 输出： | 2.5A |
| 输入电压： | 8 ~ 42 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 500kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板，文档 |
| 已用 IC / 零件： | LM3102 |
| 相关产品： | LM3102MHX-ND - IC REG BUCK SYNC ADJ 20-TSSOP LM3102MH-ND - IC REG BUCK SYNC ADJ 20TSSOP |
SNVS515G – SEPTEMBER 2007 – REVISED JANUARY 2012
Figure 24 illustrates an inductor current waveform. On average, the output current I OUT is the same as the
inductor current I L , which is the average of the rippled inductor current. In case of current limit (the current limit
portion of Figure 24 ), the next on-time will not initiate until that the current drops below 2.7A (assume the voltage
at the FB pin is lower than 0.8V). During each on-time the current ramps up an amount equal to:
I LR =
(V IN - V OUT ) x t on
L
(6)
During current limit, the LM3102 operates in a constant current mode with an average output current I OUT(CL)
equal to 2.7A + I LR / 2.
Figure 24. Inductor Current - Current Limit Operation
N-CHANNEL MOSFET AND DRIVER
The LM3102 integrates an N-Channel main MOSFET and an associated floating high voltage main MOSFET
gate driver. The gate drive circuit works in conjunction with an external bootstrap capacitor C BST and an internal
high voltage diode. C BST connecting between the BST and SW pins powers the main MOSFET gate driver during
the main MOSFET on-time. During each off-time, the voltage of the SW pin falls to approximately -1V, and C BST
charges from V CC through the internal diode. The minimum off-time of 260 ns provides enough time for charging
C BST in each cycle.
SOFT-START
The soft-start feature allows the converter to gradually reach a steady state operating point, thereby reducing
startup stresses and current surges. Upon turn-on, after V CC reaches the under-voltage threshold, an 8 μA
internal current source charges up an external capacitor C SS connecting to the SS pin. The ramping voltage at
the SS pin (and the non-inverting input of the regulation comparator as well) ramps up the output voltage V OUT in
a controlled manner.
An internal switch grounds the SS pin if any of the following three cases happens: (i) V CC is below the under-
voltage lock-out threshold; (ii) a thermal shutdown occurs; or (iii) the EN pin is grounded. Alternatively, the output
voltage can be shut off by connecting the SS pin to ground using an external switch. Releasing the switch allows
the SS pin to ramp up and the output voltage to return to normal. The shutdown configuration is shown in
Copyright ? 2007–2012, Texas Instruments Incorporated
Product Folder Links: LM3102
13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3102EVAL/NOPB | 功能描述:电源管理IC开发工具 LM3102 EVAL BOARD RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| LM3102MH | 制造商:Texas Instruments 功能描述:IC, V REG, SYNCH, 2.5A, POWERWISE |
| LM3102MH/NOPB | 功能描述:直流/直流开关调节器 SYNC 1MHZ 2.5A STEP- DOWN VLTG REG RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| LM3102MHX | 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Down 4.5V to 42V 20-Pin TSSOP EP T/R |
| LM3102MHX/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 |
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