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參數(shù)資料
| 型號(hào)： | LD2981ABXX28 |
| 廠(chǎng)商： | 意法半導(dǎo)體 |
| 元件分類(lèi)： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
| 中文描述： | 極低降穩(wěn)壓器低ESR輸出電容器兼容與抑制研究 |
| 文件頁(yè)數(shù)： | 11/17頁(yè) |
| 文件大?。?/td> | 414K |
| 代理商： | LD2981ABXX28 |
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LD2981 SERIES
11/17
APPLICATION NOTES
EXTERNAL CAPACITORS
Like any low-dropout regulator, the LD2981 requires external capacitors for regulator stability. This
capacitor must be selected to meet the requirements of minimum capacitance and equivalent series
resistance. We suggest to solder input and output capacitors as close as possible to the relative pins.
INPUT CAPACITOR
An input capacitor whose value is 1μF is required with the LD2981 (amount of capacitance can be
increased without limit). This capacitor must be located a distance of not more than 0.5" from the input pin
of the device and returned to a clean analog ground. Any good quality ceramic, tantalum or film capacitors
can be used for this capacitor.
OUTPUT CAPACITOR
The LD2981 is designed specifically to work with ceramic output capacitors. It may also be possible to use
Tantalum capacitors, but these are not as attractive for reasons of size and cost. By the way, the output
capacitor must meet both the requirement for minimum amount of capacitance and ESR (equivalent
series resistance) value. The figures 1 and 2 show the allowable ESR range as a function of the output
capacitance. These curves represent the stability region over the full temperature and I
O
range. Due to
the different loop gain, the stability improves for higher output versions and so the suggested minimum
output capacitor value, if low ESR ceramic type is used, is 1μF for output voltages equal or major than
3.8V, 2.2μF for output voltages from 2.85 to 3.3V, and 3.3μF for the other versions. However, if an output
capacitor lower than the suggested one is used, it’s possible to make stable the regulator adding a resistor
in series to the capacitor (see Figure1 & Figure2 to choose the right value according to the used version
and keeping in account that the ESR of ceramic capacitors has been measured @ 100KHz).
IMPORTANT
The output capacitor must maintain its ESR in the stable region over the full operating temperature to
assure stability. Also, capacitor tolerance and variation with temperature must be considered to assure
the minimum amount of capacitance is provided at all times. This capacitor should be located not more
than 0.5" from the output pin of the device and returned to a clean analog ground.
INHIBIT INPUT OPERATION
The inhibit pin can be used to turn OFF the regulator when pulled low, so drastically reducing the current
consumption down to less than 1μA. When the inhibit feature is not used, this pin must be tied to V
I
to
keep the regulator output ON at all times. To assure proper operation, the signal source used to drive the
inhibit pin must be able to swing above and below the specified thresholds listed in the electrical
characteristics section under V
IH
V
IL
. Any slew rate can be used to drive the inhibit.
REVERSE CURRENT
The power transistor used in the LD2981 has not an inherent diode connected between the regulator input
and output. If the output is forced above the input, no current will flow from the output to the input across
the series pass transistor. When a V
REV
voltage is applied on the output, the reverse current measured,
according to the test circuit in figure 19, flows to the GND across the two feedback resistors. This current
typical value is 160μA. R
1
and R
2
resistors are implanted type; typical values are, respectively, 42.6 K
and 51.150 K
.
相關(guān)PDF資料 |
PDF描述 |
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| LD2981ABXX30 | VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
| LD2981ABXX32 | VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
| LD2981ABXX33 | VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
| LD2981ABXX36 | VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
| LD2981CXX25 | VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LD2981ABXX30 | 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:Ultra low drop voltage regulators with inhibit low ESR output capacitors compatible |
| LD2981ABXX32 | 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
| LD2981ABXX33 | 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:Ultra low drop voltage regulators with inhibit low ESR output capacitors compatible |
| LD2981ABXX36 | 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
| LD2981ABXX38 | 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:VERY LOW DROP VOLTAGE REGULATORS WITH INHIBIT LOW ESR OUTPUT CAPACITORS COMPATIBLE |
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