- 您现在的位置：买卖IC网 > PDF目录44551 > LM2794BL/NOPB (NATIONAL SEMICONDUCTOR CORP) SWITCHED CAPACITOR REGULATOR, 675 kHz SWITCHING FREQ-MAX, PBGA14 PDF资料下载
参数资料
| 型号： | LM2794BL/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHED CAPACITOR REGULATOR, 675 kHz SWITCHING FREQ-MAX, PBGA14 |
| 封装： | LEAD FREE, CSP-14 |
| 文件页数： | 4/16页 |
| 文件大小： | 487K |
| 代理商： | LM2794BL/NOPB |
Application Information (Continued)
Output resistance results in droop in the P
OUT voltage pro-
portional to the amount of current delivered by the pump.
The P
OUT voltage is an important factor in determining the
total output current capability of an application. Taking total
output current to be the sum of all D
X output currents plus
the current delivered through the P
OUT pin, the voltage at
P
OUT can be predicted with the following equations:
I
TOTAL =ID1 +ID2 +ID3 +ID4 +IPOUT
V
POUT = 1.5xVIN ITOTAL xROUT
LED HEADROOM VOLTAGE (V
HR)
Four current sources are connected internally between P
OUT
and D
1-D4. The voltage across each current source, (VPOUT
V
DX), is referred to as headroom voltage (VHR). The cur-
rent sources require a sufficient amount of headroom voltage
to be present across them in order to regulate properly.
Minimum required headroom voltage is proportional to the
current flowing through the current source, as dictated by the
equation:
V
HR-MIN =kHR xIDX
The parameter k
HR, typically 20mV/mA in the LM2794/5, is a
proportionality constant that represents the ON-resistance of
the internal current mirror transistors. For worst-case design
calculations, using a k
HR of 25mV/mA is recommended.
(Worst-case recommendation accounts for parameter shifts
from part-to-part variation and applies over the full operating
temperature range). Figure 3 shows how output current of
the LM2794/5 varies with respect to headroom voltage.
On the flat part of the graph, the currents regulate properly
as there is sufficient headroom voltage for regulation. On the
sloping part of the graph the headroom voltage is too small,
the current sources are squeezed, and their current drive
capability is limited. Changes in headroom voltage from one
output to the next, possible with LED forward voltage mis-
match, will result in different output currents and LED bright-
ness mismatch. Thus, operating the LM2794/5 with insuffi-
cient headroom voltage across the current sources should
be avoided.
20028535
FIGURE 2. Keypad LEDs Connected to P
OUT
20028539
FIGURE 3. I
LED vs VHR
4 LEDs, V
IN = 3.0V
LM2794/LM2795
www.national.com
12
相关PDF资料 |
PDF描述 |
|---|---|
| LM2797MM-1.8/NOPB | 0.12 A SWITCHED CAPACITOR REGULATOR, PDSO10 |
| LM2797MMX-1.8/NOPB | 0.12 A SWITCHED CAPACITOR REGULATOR, PDSO10 |
| LM2798MMX-1.5/NOPB | 0.12 A SWITCHED CAPACITOR REGULATOR, 500 kHz SWITCHING FREQ-MAX, PDSO10 |
| LM2798MM-2.0/NOPB | 0.12 A SWITCHED CAPACITOR REGULATOR, 500 kHz SWITCHING FREQ-MAX, PDSO10 |
| LM2798MMX-2.0/NOPB | 0.12 A SWITCHED CAPACITOR REGULATOR, 500 kHz SWITCHING FREQ-MAX, PDSO10 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2794BLX | 制造商:Texas Instruments 功能描述: |
| LM2794EVAL | 功能描述:电源管理IC开发工具 EVAL KIT FOR LM2794 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 |
| LM2794TL | 功能描述:IC LED DRVR WHT BCKLT 14MICROSMD RoHS:否 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 恒定电流:- 恒定电压:- 拓扑:升压（升压），切换式电容器（充电泵） 输出数:1 内部驱动器:是 类型 - 主要:背光 类型 - 次要:白色 LED 频率:625kHz ~ 875kHz 电源电压:2.7 V ~ 5.3 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-µMAX 包装:带卷 (TR) 工作温度:-40°C ~ 85°C |
| LM2794TL/NOPB | 功能描述:LED照明驱动器 RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| LM2794TLX | 功能描述:IC LED DRVR WHT BCKLT 14USMD RoHS:否 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 恒定电流:- 恒定电压:- 拓扑:升压（升压），切换式电容器（充电泵） 输出数:1 内部驱动器:是 类型 - 主要:背光 类型 - 次要:白色 LED 频率:625kHz ~ 875kHz 电源电压:2.7 V ~ 5.3 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-µMAX 包装:带卷 (TR) 工作温度:-40°C ~ 85°C |
发布紧急采购，3分钟左右您将得到回复。