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參數(shù)資料
| 型號： | SA5230 |
| 廠商： | NXP Semiconductors N.V. |
| 英文描述： | Low voltage operational amplifier(低壓運算放大器) |
| 中文描述： | 低電壓運算放大器（低壓運算放大器） |
| 文件頁數(shù)： | 7/17頁 |
| 文件大小： | 189K |
| 代理商： | SA5230 |
Philips Semiconductors
Product specification
NE/SA5230
Low voltage operational amplifier
1994 Aug 31
7
Output Stage
Processing output voltage swings that nominally reach to less than
100mV of either supply voltage can only be achieved by a pair of
complementary common-emitter connected transistors. Normally,
such a configuration causes complex feed-forward signal paths that
develop by combining biasing and driving which can be found in
previous low supply voltage designs. The unique output stage of the
NE5230 separates the functions of driving and biasing, as shown in
the simplified schematic of Figure 3, and has the advantage of a
shorter signal path which leads to increasing the effective
bandwidth.
This output stage consists of two parts: the Darlington output
transistors and the class AB control regulator. The output transistor
Q3 connected with the Darlington transistors Q4 and Q5 can source
up to 10mA to an output load. The output of NPN Darlington
connected transistors Q1 and Q2 together are able to sink an output
current of 10mA. Accurate and efficient class AB control is
necessary to insure that none of the output transistors are ever
completely cut off. This is accomplished by the differential amplifier
(formed by Q8 and Q9) which controls the biasing of the output
transistors. The differential amplifier compares the summed voltages
across two diodes, D1 and D2, at the base of Q8 with the summed
voltages across the base-emitter diodes of the output transistors Q1
and Q3. The base-emitter voltage of Q3 is converted into a current
by Q6 and R6 and reconverted into a voltage across the
base-emitter diode of Q7 and R7. The summed voltage across the
base-emitter diodes of the output transistors Q3 and Q1 is
proportional to the logarithm of the product of the push and pull
currents I
OP
and I
ON
, respectively. The combined voltages across
diodes D1 and D2 are proportional to the logarithm of the square of
the reference current I
B1
. When the diode characteristics and
temperatures of the pairs Q1, D1 and Q3, Q2 are equal, the relation
I
OP
×
I
ON
=I
B1
×
I
B1
is satisfied.
Separating the functions of biasing and driving prevents the driving
signals from becoming delayed by the biasing circuit. The output
Darlington transistors are directly accessible for in-phase driving
signals on the bases of Q5 and Q2. This is very important for simple
high-frequency compensation. The output transistors can be
high-frequency compensated by Miller capacitors CM1A and CM1B
connected from the collectors to the bases of the output Darlington
transistors.
A general-purpose op amp of this type must have enough open-loop
gain for applications when the output is driving a low resistance
load. The NE5230 accomplishes this by inserting an intermediate
common-emitter stage between the input and output stages. The
three stages provide a very large gain, but the op amp now has
three natural dominant poles — one at the output of each
common-emitter stage. Frequency compensation is implemented
with a simple scheme of nested, pole-splitting Miller integrators. The
Miller capacitors CM1A and CM1B are the first part of the nested
structure, and provide compensation for the output and intermediate
stages. A second pair of Miller integrators provide pole-splitting
compensation for the pole from the input stage and the pole
resulting from the compensated combination of poles from the
intermediate and output stages. The result is a stable,
internally-compensated op amp with a phase margin of 70 degrees.
Q5
I
b1
I
b2
I
b3
I
b5
I
b4
Q4
Q6
Q8
Q9
D1
Q7
Q3
D2
Q1
Q2
R7
R6
CM1B
CM1A
V
b2
V
b5
V
CC
V
EE
V
OUT
I
OP
I
ON
SL00252
Figure 3. Output Stage
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SA5230D | Low Voltage Operational Amplifier |
| SA5230N | Low Voltage Operational Amplifier |
| SA5232 | Matched dual high-performance low-voltage operational amplifier |
| SA5232D | Matched dual high-performance low-voltage operational amplifier |
| SA5232N | Matched dual high-performance low-voltage operational amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SA5230D | 功能描述:運算放大器 - 運放 1.8V Single Rail to RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| SA5230DG | 功能描述:運算放大器 - 運放 1.8V Single Rail to Rail Industrial Temp RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| SA5230DR2 | 功能描述:運算放大器 - 運放 1.8V Single Rail to RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| SA5230DR2G | 功能描述:運算放大器 - 運放 1.8V Single Rail to Rail Industrial Temp RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| SA5230FE | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Low voltage operational amplifier |
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