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參數(shù)資料
| 型號(hào)： | SPX2954N-5.0 |
| 英文描述： | 250 mA Low Drop Out Voltage Regulator |
| 中文描述： | 250毫安低壓差穩(wěn)壓器 |
| 文件頁(yè)數(shù)： | 9/17頁(yè) |
| 文件大小： | 178K |
| 代理商： | SPX2954N-5.0 |
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9
Rev. 3/6/03
SP2954 250mA Low Dropout Voltage Regulator
Copyright 2003 Sipex Corporation
upper limit of 1.2M
on value of R
. If no load
is presented the I
produces an error of typically
2% in V
which may be eliminated at room
temperature by trimming R
. To improve the
accuracy choose the value of R
= 100k this
reduces the error by 0.17% and increases the
resistor program current by 12
μ
A. Since the
SPX2954 typically draws 60
μ
A at no load with
Pin 2 open-circuited, this is a small price to pay.
REDUCING OUTPUT NOISE
It may be an advantage to reduce the AC noise
present at the output. One way is to reduce the
regulator bandwidth by increasing the size of the
output capacitor. This is the only way that noise
can be reduced on the 3 lead SPX2954 but is
relatively inefficient, as increasing the capacitor
from 1
μ
F to 220
μ
F only decreases the noise
from 430
μ
V to 160
μ
VRMS for a 100kHz band-
width at 5V output. Noise can be reduced four-
fold by using a bypass capacitor across R
, since
it reduces the high frequency gain from 4 to
unity. Pick
C
BYPASS
(1 / 2
π
R
1
x 200 Hz)
or choose 0.01
μ
F. When doing this, the output
capacitor must be increased to 3.3
μ
F to maintain
stability. These changes reduce the output noise
from 430
μ
V to 100
μ
V
for a 100kHz band-
width at 5V output. With the bypass capacitor
added, noise no longer scales with output volt-
age so that improvements are more dramatic at
higher output voltages.
APPLICATIONS HINTS (
CONT
)
470K
ERROR
______
SD
V
OUT
GND
+V
IN
+V
IN
R
1
1
μ
F
R
2
3
8
5
1
4
+
FB
7
V
OUT
470k
SPX2954
RESET
OUTPUT
ERROR
ERROR
______
SD
V
OUT
GND
FB
+V
IN
+V
IN
*V
OUT
= V
IN
3
8
5
1
4
7
SHUTDOWN
INPUT
SPX2954
*MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40mV to 400mV.
DEPENDING ON LOAD CURRENT.
Figure 2. Latch Off when Error Flag Occurs
Figure 3. Wide Imput Voltage Range, Current Limiter
+
+
+
+
4.75V
OUTPUT
VOLTAGE
ERROR*
_______
INPUT
VOLTAGE
1.3V
5.0V
* See Application Info.
Figure 1. Error Output Timing
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SPX2954AT3-3.3 | 250 mA Low Drop Out Voltage Regulator |
| SPX2955 | 350mA Low Drop Out Voltage Regulator with Shutdown |
| SPX2956S-3.3 | 350mA Low Drop Out Voltage Regulator with Shutdown |
| SPX2956S-5.0 | 350mA Low Drop Out Voltage Regulator with Shutdown |
| SPX2957T3 | 350mA Low Drop Out Voltage Regulator with Shutdown |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SPX2954N-L-3-3 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| SPX2954S-3.3 | 制造商:Exar Corporation 功能描述:VOLTAGE REGULATOR |
| SPX2954S-3-3 | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:250mA Low Dropout Voltage Regulator |
| SPX2954S-5.0 | 制造商:Exar Corporation 功能描述:FIXED/ADJUSTABLE POSITIVE LDO REGULATOR, 0.5 V DROPOUT, 8 Pin Plastic SOP |
| SPX2954S-5-0 | 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:250mA Low Dropout Voltage Regulator |
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