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參數(shù)資料
| 型號： | LX8415-00CSTT |
| 廠商： | MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Positive Adjustable Voltage Regulator |
| 中文描述： | ADJUSTABLE POSITIVE LDO REGULATOR, 1.3 V DROPOUT, PDSO4 |
| 封裝： | PLASTIC, SOT-223, 4 PIN |
| 文件頁數(shù)： | 4/7頁 |
| 文件大小： | 191K |
| 代理商： | LX8415-00CSTT |
0.5A L
O W
D
ROPOUT
P
OSITIVE
R
EGULATORS
LX8415-xx
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
Copyright 1999
Rev. 0.4 1/99
4
P
R E L I M I N A R Y
D
A T A
S
H E E T
A P P L I C AT I O N N O T E S
The LX8415 series ICs are easy to use Low-Dropout (LDO) voltage
regulators. They have the standard self-protection features ex-
pected of a voltage regulator: short circuit protection and automatic
thermal shutdown if the device temperature rises above approxi-
mately 165°C.
Use of an output capacitor is REQUIRED with the LX8415 series.
Please see the table below for recommended minimum capacitor
values.
These regulators offer a more tightly controlled reference voltage
tolerance and superior reference stability when measured against
the older pin-compatible regulator types that they replace.
STABILITY
The output capacitor is part of the regulator’s frequency compen-
sation system. Many types of capacitors are available, with different
capacitance value tolerances, capacitance temperature coefficients,
and equivalent series impedances. For all operating conditions,
connection of a 220μF aluminum electrolytic capacitor or a 47μF
solid tantalum capacitor between the output terminal and ground
will guarantee stable operation.
If a bypass capacitor is connected between the output voltage
adjust (ADJ) pin and ground, ripple rejection will be improved
(please see the section entitled “
RIPPLE REJECTION
”). When ADJ
pin bypassing is used, the required output capacitor value increases.
Output capacitor values of 220μF (aluminum) or 47μF (tantalum)
provide for all cases of bypassing the ADJ pin. If an ADJ pin bypass
capacitor is not used, smaller output capacitor values are adequate.
The table below shows recommended minimum capacitance values
for stable operation.
INPUT
10μF
10μF
OUTPUT
ADJ
None
15μF
15μF Tantalum, 100μF Aluminum
47μF Tantalum, 220μF Aluminum
In order to ensure good transient response from the power supply
system under rapidly changing current load conditions, designers
generally use several output capacitors connected in parallel. Such
an arrangement serves to minimize the effects of the parasitic
resistance (ESR) and inductance (ESL) that are present in all
capacitors. Cost-effective solutions that sufficiently limit ESR and
ESL effects generally result in total capacitance values in the range
of hundreds to thousands of microfarads, which is more than
adequate to meet regulator output capacitor specifications. Output
capacitance values may be increased without limit.
The circuit shown in Figure 1 can be used to observe the transient
response characteristics of the regulator in a power system under
changing loads. The effects of different capacitor types and values
on transient response parameters, such as overshoot and under-
shoot, can be quickly compared in order to develop an optimum
solution.
RECOMMENDED CAPACITOR VALUES
FIGURE 1
— DYNAMIC INPUT and OUTPUT TEST
LX8415-xx
Power Supply
OUT
IN
ADJ
Star Ground
1 sec
10ms
R
DSON
<< R
L
Full Load
(Smaller resistor)
Minumum Load
(Larger resistor)
C
1
C
2
RIPPLE REJECTION
Ripple rejection can be improved by connecting a capacitor
between the ADJ pin and ground. The value of the capacitor should
be chosen so that the impedance of the capacitor is equal in
magnitude to the resistance of R1
at the ripple frequency
. The
capacitor value can be determined by using this equation:
C = 1 / (6.28 * F
R
* R1)
where: C
≡
the value of the capacitor in Farads;
select an equal or larger standard value.
≡
the ripple frequency in Hz
≡
the value of resistor R1 in ohms
F
R
R1
At a ripple frequency of 120Hz, with R1 = 100
:
C = 1 / (6.28 * 120Hz * 100
) = 13.3μF
The closest equal or larger standard value should be used, in this
case, 15μF.
When an ADJ pin bypass capacitor is used, output ripple
amplitude will be essentially independent of the output voltage. If
an ADJ pin bypass capacitor is not used, output ripple will be
proportional to the ratio of the output voltage to the reference
voltage:
M = V
OUT
/V
REF
where: M
≡
a multiplier for the ripple seen when the
ADJ pin is optimally bypassed.
V
REF
= 1.25V.
For example, if V
OUT
= 2.5V the output ripple will be:
M = 2.5V/1.25V= 2
Output ripple will be twice as bad as it would be if the ADJ pin
were to be bypassed to ground with a properly selected capacitor.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LX8415-25 | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:0.5 A LOW DROPOUT POSITIVE REGULATORS |
| LX8415-25CST | 功能描述:IC REG LDO 2.5V SOT-223 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式和可調(diào)式 輸出電壓:3.3V，1.25 V ~ 5.7 V 輸入電壓:4.5 V ~ 7 V 電壓 - 壓降（標(biāo)準(zhǔn)）:1.1V @ 1A 穩(wěn)壓器數(shù)量:2 電流 - 輸出:1A 電流 - 限制（最?。?1A 工作溫度:0°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:TO-252-5，DPak（4 引線 + 接片），TO-252AD 供應(yīng)商設(shè)備封裝:PPAK 包裝:管件 其它名稱:497-3576-5 |
| LX8415-25CSTT | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:Positive Fixed Voltage Regulator |
| LX8415-33 | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:0.5 A LOW DROPOUT POSITIVE REGULATORS |
| LX8415-33CST | 功能描述:IC REG LDO 3.3V SOT-223 RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式和可調(diào)式 輸出電壓:3.3V，1.25 V ~ 5.7 V 輸入電壓:4.5 V ~ 7 V 電壓 - 壓降（標(biāo)準(zhǔn)）:1.1V @ 1A 穩(wěn)壓器數(shù)量:2 電流 - 輸出:1A 電流 - 限制（最?。?1A 工作溫度:0°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:TO-252-5，DPak（4 引線 + 接片），TO-252AD 供應(yīng)商設(shè)備封裝:PPAK 包裝:管件 其它名稱:497-3576-5 |
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