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參數(shù)資料
| 型號： | LM2931DT-1-5.0 |
| 廠商： | MOTOROLA INC |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | LOW DROPOUT VOLTAGE REGULATORS |
| 中文描述： | 5 V FIXED POSITIVE LDO REGULATOR, 0.6 V DROPOUT, PSSO2 |
| 封裝： | PLASTIC, DPAK-3 |
| 文件頁數(shù)： | 6/6頁 |
| 文件大?。?/td> | 360K |
| 代理商： | LM2931DT-1-5.0 |
++,3
One of the distinguishing factors of the
LM
2931 series
regulators is the requirement of an output capacitor for device
stability. The value required varies greatly depending upon the
application circuit and other factors. Thus some comments on
the characteristics of both capacitors and the regulator are in
order.
High frequency characteristics of electrolytic capacitors
depend greatly on the type and even the manufacturer. As a
result, a value of capacitance that works well with the
LM
2931
for one brand or type may not necessary be sufficient with an
electrolytic of different origin. Sometimes actual bench
testing, as described later, will be the only means to determine
the proper capacitor and value. Experience has shown that, as
a rule of thumb, the more expensive and higher quality
electrolytics generally allow a smaller value for regulator
stability. As an example, while a high-quality 100
"
F
aluminum electrolytic covers all general application circuits,
similar stability can be obtained with a tantalum electrolytic of
only 47
"
F. This factor of two can generally be applied to any
special application circuit also.
Another critical characteristic of electrolytics is their
performance over temperature. While the
LM
2931 is designed
to operate to -40
, the same is not always true with all
electrolytics(hot is generally not a problem). The electrolyte in
many aluminum types will freeze around -30
effective value to zero. Since the capacitance is needed for
regulator stability, the natural result is oscillation (and lots of
it)at the regulator output. For all application circuits where
cold operation is necessary, the output capacitor must be rated
to operate at the minimum temperature. By coincidence,
worst-case stability for the
LM
2931 also occurs at minimum
temperatures. As a result, in applications where the regulator
junction temperature will never be less than 25
capacitor can be reduced approximately by a factor of two
over the value needed for the entire temperature range. To
continue our example with the tantalum electrolytic, a value of
only 22
"
F would probably thus suffice. For high-quality
aluminum, 47
"
F would be adequate in such an application.
Another regulator characteristic that is noteworthy is that
stability decreases with higher output currents. This sensible
fact has important connotations. In many applications, the
LM
2931 is operated at only a few milliamps of output current
or less. In such a circuit, the output capacitor can be further
reduced in value. As a rough estimation, a circuit that is
required to deliver a maximum of 10mAof output current from
the regulator would need an output capacitor of only half the
value compared to the same regulator required to deliver the
full output current of 100mA. If the example of the tantalum
capacitor in the circuit rated at 25
above were continued to include a maximum of 10 mA of
output current, then the 22
#"
F output capacitor could be
reduced to only 10
#"
F.
,reducing their
, the output
junction temperature and
In the case of the
LM
2931CT adjustable regulator, the
minimum
value of output capacitance is a function of the output voltage.
As a general rule, the value decreases with higher output
voltages, since internal loop gain is reduced.
At this point, the procedure for bench testing the minimum
value of an output capacitor in a special application circuit
should be clear. Since worst-case occurs at minimum
operating temperatures and maximum operating currents, the
entire circuit, including the electrolytic, should be cooled to
the minimum temperature. The input voltage to the regulator
should be maintained at 0.6V above the output to keep internal
power dissipation and die heating to a minimum. Worst-case
occurs just after input power is applied and before the die has
had a chance to heat up. Once the minimum value of
capacitance has been found for the brand and type of
electrolytic in question, the value should be doubled for actual
use to account for production variations both in the capacitor
and the regulator.(All the values in this section and the
remainder of the data sheet were determined in this fashion.)
--'
'+ 4
The input-output voltage differential at
which the circuit ceases to regulate against further reduction
in input voltage. Measured when the output voltage has
dropped 100 mV from the nominal value obtained at 14V
input, dropout voltage is dependent upon load current and
junction temperature.
+4
The DC voltage applied to the input terminals
with respect to ground.
+#+ --'4
The voltage difference between
the unregulated input voltage and the regulated output voltage
for which the regulator will operate.
4
The change in output voltage for a change
in the input voltage. The measurement is made under
conditions of low dissipation or by using pulse techniques
such that the average chip temperature is not significantly
affected.
(4
The change in output voltage for a change
in load current at constant chip temperature.
' *4
Output voltage stability under
accelerated life-test conditions after 1000 hours with
maximum rated voltage and junction temperature.
+ 54
The rms AC voltage at the output,
with constant load and no input ripple, measured over a
specified frequency range.
6, ''4
That part of the positive input current
that does not contribute to the positive load current. The
regulator ground lead current.
++7,4
The ratio of the peak-to-peak input ripple
voltage to the peak-to-peak output ripple voltage.
+'' * - 4
output voltage for a thermal variation from room temperature
true to either temperature extreme.
The percentage change in
LM2931-5.0
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM2931DT-5.0 | POT 100 OHM 3/4 RECT WW SL MT |
| LM2931T-5.0 | LOW DROPOUT VOLTAGE REGULATORS |
| LM2931D2T-5.0 | LOW DROPOUT VOLTAGE REGULATORS |
| LM2931AD2T-5.0 | LOW DROPOUT VOLTAGE REGULATORS |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2931DT-5.0 | 功能描述:低壓差穩(wěn)壓器 - LDO 5V 100mA 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(fù)載調(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| LM2931DT-5.0G | 功能描述:低壓差穩(wěn)壓器 - LDO 5V 100mA w/Load Dump 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(fù)載調(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| LM2931DT-5.0G | 制造商:ON Semiconductor 功能描述:IC LDO VOLT REG 5V 0.1A D-PAK-3 |
| LM2931IBP-3.3 | 功能描述:IC REG LDO 3.3V .1A 6USMD RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:4V 輸入電壓:最高 16V 電壓 - 壓降（標(biāo)準(zhǔn)）:0.28V @ 150mA 穩(wěn)壓器數(shù)量:1 電流 - 輸出:150mA 電流 - 限制（最小）:- 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:5-VFBGA 供應(yīng)商設(shè)備封裝:5-uSMD 包裝:Digi-Reel® 其它名稱:LP2985AIBP-4.0DKR |
| LM2931IBP-5.0 | 制造商:Texas Instruments 功能描述:LDO Regulator Pos 5V 0.1A 6-Pin uSMD T/R |
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