- 您现在的位置：买卖IC网 > PDF目录17421 > LM2621EVAL/NOPB (National Semiconductor)EVALUATION BOARD FOR LM2621 PDF资料下载
参数资料
| 型号： | LM2621EVAL/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 6/17页 |
| 文件大小： | 0K |
| 描述： | EVALUATION BOARD FOR LM2621 |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步升 |
| 输出及类型： | 1，非隔离 |
| 输入电压： | 1.2 ~ 14 V |
| 稳压器拓扑结构： | 升压 |
| 板类型： | 完全填充 |
| 已供物品： | 板，文档 |
| 已用 IC / 零件： | LM2621 |
SNVS033C – MAY 2004 – REVISED MARCH 2005
DETAILED DESCRIPTION
OPERATING PRINCIPLE
The LM2621 is designed to provide step-up DC-DC voltage regulation in battery-powered and low-input voltage
systems. It combines a step-up switching regulator, N-channel power MOSFET, built-in current limit, thermal
limit, and voltage reference in a single 8-pin VSSOP package Figure 13 . The switching DC-DC regulator boosts
an input voltage between 1.2V and 14V to a regulated output voltage between 1.24V and 14V. The LM2621
starts from a low 1.1V input and remains operational down to 0.65V.
This device is optimized for use in cellular phones and other applications requiring a small size, low profile, as
well as low quiescent current for maximum battery life during stand-by and shutdown. A high-efficiency gated-
oscillator topology offers an output of up to 1A.
Additional features include a built-in peak switch current limit, and thermal protection circuitry.
Figure 13. Functional Diagram
GATED OSCILLATOR CONTROL SCHEME
A unique gated oscillator control scheme enables the LM2621 to have an ultra-low quiescent current and
provides a high efficiency over a wide load range. The switching frequency of the internal oscillator is
programmable using an external resistor and can be set between 300 kHz and 2 MHz.
This control scheme uses a hysteresis window to regulate the output voltage. When the output voltage is below
the upper threshold of the window, the LM2621 switches continuously with a fixed duty cycle of 70% at the
switching frequency selected by the user. During the first part of each switching cycle, the internal N-channel
MOSFET switch is turned on. This causes the current to ramp up in the inductor and store energy. During the
second part of each switching cycle, the MOSFET is turned off. The voltage across the inductor reverses and
forces current through the diode to the output filter capacitor and the load. Thus when the LM2621 switches
continuously, the output voltage starts to ramp up. When the output voltage hits the upper threshold of the
window, the LM2621 stops switching completely. This causes the output voltage to droop because the energy
stored in the output capacitor is depleted by the load. When the output voltage hits the lower threshold of the
hysteresis window, the LM2621 starts switching continuously again causing the output voltage to ramp up
towards the upper threshold. Figure 14 shows the switch voltage and output voltage waveforms.
6
Product Folder Links: LM2621
Copyright ? 2004–2005, Texas Instruments Incorporated
相关PDF资料 |
PDF描述 |
|---|---|
| MAX6241AESA+ | IC VREF SERIES BURIED ZNR 8-SOIC |
| F970J107KNC | CAP TANT 100UF 6.3V 10% SMD |
| R1S8-0505/P-R | CONV DC/DC 1W 05VIN 05VOUT |
| MAX6225AESA+ | IC VREF SERIES BURIED ZNR 8-SOIC |
| TARW686M006 | CAP TANT 68UF 6.3V 20% AXIAL |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2621MM | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM2621MM | 制造商:Texas Instruments 功能描述:DC/DC UP CONVERTER ADJ SMD 2621 |
| LM2621MM/NOPB | 功能描述:DC/DC 开关控制器 LOW INP VLTG,STEP-UP DC-DC RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM2621MM/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu |
| LM2621MMX | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
发布紧急采购，3分钟左右您将得到回复。