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參數(shù)資料
| 型號： | LP2985AIM5X-4.7 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | Micropower 150 mA Low-Noise Ultra Low-Dropout Regulator Designed for Use with Very Low ESR Output Capacitors |
| 中文描述： | 4.7 V FIXED POSITIVE LDO REGULATOR, 0.575 V DROPOUT, PDSO5 |
| 封裝： | SOT-23, 5 PIN |
| 文件頁數(shù)： | 11/23頁 |
| 文件大?。?/td> | 528K |
| 代理商： | LP2985AIM5X-4.7 |
SLVS522C JULY 2004 REVISED OCTOBER 2004
11
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
APPLICATION INFORMATION
capacitor characteristics
ceramics
Ceramic capacitors are ideal choices for use on the output of the LP2985 for several reasons. For capacitances
in the range of 2.2
μ
F to 4.7
μ
F, ceramic capacitors have the lowest cost and the lowest ESR, making them
choice candidates for filtering high-frequency noise. For instance, a typical 2.2-
μ
F ceramic capacitor has an
ESR in the range of 10 m
to 20 m
and, thus, satisfies minimum ESR requirements of the regulator.
Ceramic capacitors have one glaring disadvantage that must be taken into account a poor temperature
coefficient, where the capacitance can vary significantly with temperature. For instance, a large-value ceramic
capacitor (
≥
2.2
μ
F) can lose more than half of its capacitance as the temperature rises from 25
°
C to 85
°
C. Thus,
a 2.2-
μ
F capacitor at 25
°
C will drop well below the minimum C
out
required for stability, as ambient temperature
rises. For this reason, select an output capacitor that maintains the minimum 2.2
μ
F required for stability over
the
entire operating temperature range
. Note that there are some ceramic capacitors that can maintain a
±
15%
capacitance tolerance over temperature.
tantalum
Tantalum capacitors can be used at the output of the LP2985, but there are significant disadvantages that could
prohibit their use:
In the 1-
μ
F to 4.7-
μ
F range, tantalum capacitors are more expensive than ceramics of the equivalent
capacitance and voltage ratings.
Tantalum capacitors have higher ESRs than their equivalent-sized ceramic counterparts. Thus, to meet
the ESR requirements, a higher-capacitance tantalum may be required, at the expense of larger size
and higher cost.
The ESR of a tantalum capacitor increases as temperature drops, as much as double from 25
°
C to
40
°
C. Thus, ESR margins must be maintained over the temperature range in order to prevent
regulator instability.
ON/OFF operation
The LP2985 allows for a shutdown mode via the ON/OFF pin. Driving the pin LOW (
≤
0.3 V) turns the device
OFF; conversely, a HIGH (
≥
1.6 V) turns the device ON. If the shutdown feature is not used, ON/OFF should be
connected to the input to ensure that the regulator is on at all times. For proper operation, do not leave ON/OFF
unconnected, and apply a signal with a slew rate of
≥
40 mV/
μ
s.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LP2985AIM5X-5.0 | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| LP2985AIM5X-5.0/NOPB | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| LP2985AIM5X-5.0NOPB | 制造商:National Semiconductor 功能描述:LDO Regulator Pos 5V 0.15A 5-Pin SOT-23 T/R |
| LP2985AIM5X-5.7/NOPB | 功能描述:低壓差控制器 - LDO MicroPwr 150mA Lo Noise Ultra LDO Reg RoHS:否 制造商:Micrel 最大輸入電壓:5.5 V 輸出電壓:Adjustable 輸出電流:10 mA 負載調節(jié): 輸出類型:Adjustable, Fixed 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-6 |
| LP2985AIM5X-6.1 | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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