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参数资料
| 型号： | LM2621EVAL |
| 厂商： | National Semiconductor |
| 文件页数： | 7/17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 |
| 相关产品： | LM2621MMDKR-ND - IC REG BST FLYBK SEPIC ADJ 8MSOP LM2621MMX/NOPBTR-ND - IC REG BST FLYBK SEPIC ADJ 8MSOP LM2621MMTR-ND - IC REG BST FLYBK SEPIC ADJ 8MSOP LM2621MMCT-ND - IC REG BST FLYBK SEPIC ADJ 8MSOP |
| 其它名称： | *LM2621EVAL |
SNVS033C – MAY 2004 – REVISED MARCH 2005
Because of this type of control scheme, the quiescent current is inherently very low. At light loads the gated
oscillator control scheme offers a much higher efficiency compared to the conventional PWM control scheme.
Figure 14. Typical Step-Up Regulator Waveforms
LOW VOLTAGE START-UP
The LM2621 can start-up from input voltages as low as 1.1V. On start-up, the control circuitry switches the N-
channel MOSFET continuously at 70% duty cycle until the output voltage reaches 2.5V. After this output voltage
is reached, the normal step-up regulator feedback and gated oscillator control scheme take over. Once the
device is in regulation it can operate down to a 0.65V input, since the internal power for the IC can be boot-
strapped from the output using the V DD pin.
SHUTDOWN
The LM2621 features a shutdown mode that reduces the quiescent current to less than a ensured 2.5μA over
temperature. This extends the life of the battery in battery powered applications. During shutdown, all feedback
and control circuitry is turned off. The regulator's output voltage drops to one diode drop below the input voltage.
Entry into the shutdown mode is controlled by the active-low logic input pin EN (Pin 2). When the logic input to
this pin pulled below 0.15V DD , the device goes into shutdown mode. The logic input to this pin should be above
0.7V DD for the device to work in normal step-up mode.
OUTPUT VOLTAGE RIPPLE FREQUENCY
A major component of the output voltage ripple is due to the hysteresis used in the gated oscillator control
scheme. The frequency of this voltage ripple is proportional to the load current. The frequency of this ripple does
not necessitate the use of larger inductors and capacitors however, since the size of these components is
determined by the switching frequency of the oscillator which can be set upto 2MHz using an external resistor.
INTERNAL CURRENT LIMIT AND THERMAL PROTECTION
An internal cycle-by-cycle current limit serves as a protection feature. This is set high enough (2.85A typical,
approximately 4A maximum) so as not to come into effect during normal operating conditions. An internal thermal
protection circuitry disables the MOSFET power switch when the junction temperature (T J ) exceeds about 160°C.
The switch is re-enabled when T J drops below approximately 135°C.
Copyright ? 2004–2005, Texas Instruments Incorporated
Product Folder Links: LM2621
7
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2621EVAL/NOPB | 功能描述:电源管理IC开发工具 EVAL BOARDFOR LM2621 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 |
| 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 |
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