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參數(shù)資料
| 型號： | ILC7083AIM525X |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | 150mA SOT-23 Low Noise CMOS RF-LDO⑩ Regulator |
| 中文描述： | 2.5 V FIXED POSITIVE LDO REGULATOR, 0.3 V DROPOUT, PDSO5 |
| 封裝： | PLASTIC, SOT-23, 5 PIN |
| 文件頁數(shù)： | 8/16頁 |
| 文件大?。?/td> | 472K |
| 代理商： | ILC7083AIM525X |
ILC7083/ILC7084
8
REV. 1.0.9 1/28/03
The Effects of ESR (Equivalent Series
Resistance)
The ESR of a capacitor is a measure of the resistance due to
the leads and the internal connections of the component.
Typically measured in m
(milli-ohms) it can increase to
ohms in some cases.
Wherever there is a combination of resistance and current,
voltages will be present. The control functions of LDOs use
two voltages in order to maintain the output precisely; V
OUT
and V
REF
.
With reference to the block diagram in Figure 4, V
OUT
is fed
back to the error amplifier and is used as the supply voltage
for the internal components of the ILC7083/ILC7084. So
any change in V
OUT
will cause the error amplifier to try to
compensate to maintain V
OUT
at the set level and noise on
V
OUT
will be reflected into the supply of each internal
components of the ILC7083/ILC7084. So any change in
V
OUT
will cause the error amplifier to try to compensate to
maintain V
OUT
at the set level and noise on V
OUT
will be
reflected into the supply of each internal circuit. The refer-
ence voltage, V
REF
, is influenced by the C
NOISE
pin. Noise
into this pin will add to the reference voltage and be fed
through the circuit. These factors will not cause a problem if
some simple steps are taken. Figure 5 shows where these
added ESR resistances are present in the typical LDO circuit.
Figure 5. ESR Present in C
OUT
and C
NOISE
With this in mind low ESR components will offer better
performance where the LDO may be subjected to large load
transients current. ESR is less of a problem with C
IN
as the
voltage fluctuations at the input will be filtered by the LDO.
However, being aware of these current flows, there is also
another potential source of induced voltage noise from the
resistance inherent in the PCB trace. Figure 6 shows where
the additive resistance of the PCB can manifest itself. Again
these resistances may be very small, but a summation of
several currents can develop detectable voltage ripple and
will be amplified by the LDO. Particularly the accumulation
of current flows in the ground plane can develop significant
voltages unless care is taken. With a degree of care, the
ILC7083/ILC7084 will yield outstanding performance.
Printed Circuit Board Layout Guidelines
As was mentioned in the previous section, to take full advan-
tage of any high performance LDO regulator requires paying
careful attention to grounding and printed circuit board
(PCB) layout.
Figure 6. Inherent PCB resistance
Figure 7 shows the effects of poor grounding and PCB
layout magnified by the ESR and PCB resistances and
the accumulation of current flows.
Note that particularly during high output load current, the
LDO regulator’s ground pin and the ground return for C
OUT
and C
NOISE
are not at the same potential as the system
ground. This is due to high frequency impedance caused by
PCB’s trace inductance and DC resistance. The current loop
between C
OUT
, C
NOISE
and the LDO regulator’s ground pin
will degrade performance of the LDO.
Figure 8 shows an optimum schematic. In this schematic,
high output surge current has little effect on the ground cur-
rent and noise bypass current return of the LDO regulator.
Note that the key difference here is that C
OUT
and C
NOISE
are
directly connected to the LDO regulator’s ground pin. The
LDO is then separately connected to the main ground plane
and returned to a single point system ground.
The layout of the LDO and its external components are also
based on some simple rules to minimize EMI and output
voltage ripple.
ILC7083
V
IN
SOT-23-5
C
IN
ON
OFF
1
2
3
4
5
C
NOISE
RF LDO
TM
Regulator
R*
R*
R
C
V
OUT
C
OUT
I
C
I
OUT
ILC7083
SOT-23-5
ON
OFF
1
2
3
4
5
C
NOISE
R
PCB
ESR
R
PCB
V
IN
C
IN
I
OUT
C
OUT
I
1
E
V
OUT
R
PCB
R
PCB
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| ILC7083AIM527X | 功能描述:低壓差穩(wěn)壓器 - LDO 150ma CMOS RF-LDO Ultra Low Noise 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| ILC7083AIM5285X | 功能描述:低壓差穩(wěn)壓器 - LDO 150ma CMOS RF-LDO Ultra Low Noise 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| ILC7083AIM530X | 功能描述:低壓差穩(wěn)壓器 - LDO 150ma CMOS RF-LDO Ultra Low Noise 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| ILC7083AIM533X | 功能描述:低壓差穩(wěn)壓器 - LDO 150ma CMOS RF-LDO Ultra Low Noise 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| ILC7083AIM536X | 功能描述:低壓差穩(wěn)壓器 - LDO 150ma CMOS RF-LDO Ultra Low Noise 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(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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