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参数资料
| 型号： | LP2988AILD-5 |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 固定正电压单路输出LDO稳压器 |
| 英文描述： | Micropower, 200 mA Ultra Low-Dropout Voltage Regulator with Programmable Power-On Reset Delay; Low Noise Version Available (LP2988) |
| 中文描述： | 5 V FIXED POSITIVE LDO REGULATOR, 0.35 V DROPOUT, PDSO8 |
| 封装： | LLP-8 |
| 文件页数： | 11/23页 |
| 文件大小： | 1033K |
| 代理商： | LP2988AILD-5 |
Application Hints (Continued)
IMPORTANT: The output capacitor must maintain its ESR in
the stable region over the full operating temperature range of
the application to assure stability.
The minimum required amount of output capacitance is
4.7 F. Output capacitor size can be increased without limit.
It is important to remember that capacitor tolerance and
variation with temperature must be taken into consideration
when selecting an output capacitor so that the minimum
required amount of output capacitance is provided over the
full operating temperature range. A good Tantalum capacitor
will show very little variation with temperature, but a ceramic
may not be as good (see next section).
The output capacitor should be located not more than 0.5”
from the output pin and returned to a clean analog ground.
CAPACITOR CHARACTERISTICS
TANTALUM: A solid tantalum capacitor is the best choice for
the output capacitor on the LM2987/8. Available from many
sources, their typical ESR is very close to the ideal value
required on the output of many LDO regulators.
Tantalums also have good temperature stability: a 4.7 F
was tested and showed only a 10% decline in capacitance
as the temperature was decreased from +125C to 40C.
The ESR increased only about 2:1 over the same range of
temperature.
However, it should be noted that the increasing ESR at lower
temperatures present in all tantalums can cause oscillations
when marginal quality capacitors are used (where the ESR
of the capacitor is near the upper limit of the stability range at
room temperature).
CERAMIC: The ESR of ceramic capacitor can be low
enough to cause an LDO regulator to oscillate: a 2.2 F
ceramic was measured and found to have an ESR of 15 m
.
If a ceramic capacitor is to be used on the LP2987/8 output,
a1
resistor should be placed in series with the capacitor to
provide a minimum ESR for the regulator.
A disadvantage of ceramic capacitors is that their capaci-
tance varies a lot with temperature: Large ceramic capaci-
tors are typically manufactured with the Z5U temperature
characteristic, which results in the capacitance dropping by
50% as the temperature goes from 25C to 80C.
This means you have to buy a capacitor with twice the
minimum C
OUT to assure stable operation up to 80C.
ALUMINUM: The large physical size of aluminum electrolyt-
ics makes them unsuitable for most applications. Their ESR
characteristics are also not well suited to the requirements of
LDO regulators. The ESR of a typical aluminum electrolytic
is higher than a tantalum, and it also varies greatly with
temperature.
A typical aluminum electrolytic can exhibit an ESR increase
of 50X when going from 20C to 40C. Also, some alumi-
num electrolytics can not be used below 25C because the
electrolyte will freeze.
POWER-ON RESET DELAY
A power-on reset function can be easily implemented using
the LP2987/8 by adding a single external capacitor to the
Delay pin. The Error output provides the power-on reset
signal when input power is applied to the regulator.
The reset signal stays low for a pre-set time period after
power is applied to the regulator, and then goes high (see
Timing Diagram below).
10001709
Timing Diagram for Power-Up
The external capacitor c
DLY sets the delay time (TDELAY).
The value of capacitor required for a given time delay may
be calculated using the formula:
C
DLY =TDELAY/(5.59 X 10
5)
To simplify design, a plot is provided below which shows
values of C
DLY versus delay time.
10001711
Plot of C
DLY vs TDELAY
LP2987/LP2988
www.national.com
19
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LP2988AILD-5.0 | 功能描述:IC REG LDO 5V .2A 8LLP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:1 系列:- 稳压器拓扑结构:正，固定式 输出电压:4V 输入电压:最高 16V 电压 - 压降（标准）:0.28V @ 150mA 稳压器数量:1 电流 - 输出:150mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:5-VFBGA 供应商设备封装:5-uSMD 包装:Digi-Reel® 其它名称:LP2985AIBP-4.0DKR |
| LP2988AILDX-3.8 | 功能描述:IC REG LDO 3.8V .2A 8-LLP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 稳压器拓扑结构:正，固定式 输出电压:3.1V 输入电压:最高 5.5V 电压 - 压降（标准）:- 稳压器数量:1 电流 - 输出:300mA 电流 - 限制（最小）:420mA 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 供应商设备封装:TSOT-23-5 包装:带卷 (TR) |
| LP2988AIM-2.5 | 制造商:Rochester Electronics LLC 功能描述:200MA POWER LDO - Bulk 制造商:Texas Instruments 功能描述: |
| LP2988AIM-2.5/NOPB | 功能描述:IC REG LDO 2.5V .2A 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:1 系列:- 稳压器拓扑结构:正，固定式 输出电压:4V 输入电压:最高 16V 电压 - 压降（标准）:0.28V @ 150mA 稳压器数量:1 电流 - 输出:150mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:5-VFBGA 供应商设备封装:5-uSMD 包装:Digi-Reel® 其它名称:LP2985AIBP-4.0DKR |
| LP2988AIM-2.8/NOPB | 功能描述:IC REG LDO 2.8V .2A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:1 系列:- 稳压器拓扑结构:正，固定式 输出电压:4V 输入电压:最高 16V 电压 - 压降（标准）:0.28V @ 150mA 稳压器数量:1 电流 - 输出:150mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:5-VFBGA 供应商设备封装:5-uSMD 包装:Digi-Reel® 其它名称:LP2985AIBP-4.0DKR |
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