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参数资料
| 型号： | SSM-2275 |
| 厂商： | Analog Devices, Inc. |
| 元件分类： | 运动控制电子 |
| 英文描述： | Single Audio Amplifier |
| 中文描述： | 单音频放大器 |
| 文件页数： | 9/16页 |
| 文件大小： | 192K |
| 代理商： | SSM-2275 |
SSM2275/SSM2475
REV. A
–9–
±
7 V, then the input current should be limited to less than
±
5 mA. This can be easily done by placing a resistor in series
with both inputs. The minimum value of the resistor can be
determined by:
R
V
IN
DIFF MAX
0 01
=
7
(1)
There are also ESD protection diodes that are connected from
each input to each power supply rail. These diodes are normally
reversed biased, but will turn on if either input voltage exceeds
either supply rail by more than 0.6 V. Again, should this condi-
tion occur the input current should be limited to less than
±
5 mA. The minimum resistor value should then be:
R
V
mA
5
IN
IN MAX
=
(2)
In practice, R
IN
should be placed in series with both inputs to
reduce offset voltages caused by input bias current. This is
shown in Figure 28.
R
IN
R
IN
V+
V–
Figure 28. Using Resistors for Input Overcurrent Protection
Output Voltage Phase Reversal
The SSM2275/SSM2475 was designed to have a wide common-
mode range and is immune to output voltage phase reversal with
an input voltage within the supply voltages of the device. How-
ever, if either of the device’s inputs exceeds 0.6 V above the posi-
tive voltage supply, the output could exhibit phase reversal.
This is due to the input transistor’s B–C junction becoming for-
ward biased, causing the polarity of the input terminals of the
device to switch.
THEORY OF OPERATION
The SSM2275 and SSM2475 are low noise and low distortion
rail-to-rail output amplifiers that are excellent for audio applica-
tions. Based on the OP275 audiophile amplifier, the SSM2275/
SSM2475 offers many similar performance characteristics with
the advantage of a rail-to-rail output from a single supply
source. Its low input voltage noise figure of 7 nV/
√
Hz
allows the
device to be used in applications requiring high gain, such as
microphone preamplifiers. Its 11 V/
μ
s slew rate also allows the
SSM2275/SSM2475 to produce wide output voltage swings
while maintaining low distortion. In addition, its low harmonic
distortion figure of 0.0006% makes the SSM2275 and
SSM2475 ideal for high quality audio applications.
Figure 27 shows the simplified schematic for a single amplifier.
The amplifier contains a Butler Amplifier at the input. This
front-end design uses both bipolar and MOSFET transistors in
the differential input stage. The bipolar devices, Q1 and Q2,
improve the offset voltage and achieve the low noise perfor-
mance, while the MOS devices, M1 and M2, are used to obtain
higher slew rates. The bipolar differential pair is biased with a
proportional-to-absolute-temperature (PTAT) bias source, IB1,
while the MOS differential pair is biased with a non-PTAT
source, IB2. This results in the amplifier having a constant gain-
bandwidth product and a constant slew rate over temperature.
The amplifier also contains a rail-to-rail output stage that can
sink or source up to 50 mA of current. As with any rail-to-rail
output amplifier the gain of the output stage, and consequently
the open loop gain of the amplifier, is proportional to the load
resistance. With a load resistance of 50 k
, the dc gain of the
amplifier is over 110 dB. At load currents less than 1 mA, the
output of the amplifier can swing to within 30 mV of either sup-
ply rail. As load current increases, the maximum voltage swing
of the output will decrease. This is due to the collector to emit-
ter saturation voltage of the output transistors increasing with an
increasing collector current.
Input Overvoltage Protection
The maximum input differential voltage that can be applied to
the SSM2275/SSM2475 is
±
7 V. A pair of internal back-to-back
Zener diodes are connected across the input terminals. This
prevents emitter-base junction breakdown from occurring to the
input transistors, Q1 and Q2, when very large differential volt-
ages are applied. If the device’s differential voltage could exceed
Q2
IN+
IB2
IN–
Q1
M2
M1
IB1
CFI
OUT
V
CC
V
EE
Figure 27. Simplified Schematic
相关PDF资料 |
PDF描述 |
|---|---|
| SSM2475 | Single Audio Amplifier |
| SSM2275 | Single Audio Amplifier |
| SSM2275P | Single Audio Amplifier |
| SSM2275RM | Single Audio Amplifier |
| SSM2275S | Single Audio Amplifier |
相关代理商/技术参数 |
参数描述 |
|---|---|
| SSM2275P | 制造商:AD 制造商全称:Analog Devices 功能描述:Rail-to-Rail Output Audio Amplifiers |
| SSM2275RM | 制造商:AD 制造商全称:Analog Devices 功能描述:Rail-to-Rail Output Audio Amplifiers |
| SSM2275S | 制造商:Analog Devices 功能描述:Operational Amplifier, Dual AMP, Bipolar/MOS, 8 Pin, Plastic, SOP |
| SSM22LLPT | 制造商:未知厂家 制造商全称:未知厂家 功能描述:SCHOTTKY BARRIER RECTIFIER VOLTAGE RANGE 20 Volts CURRENT 2.0 Amperes |
| SSM22LPT | 制造商:未知厂家 制造商全称:未知厂家 功能描述:SURFACE MOUNT SCHOTTKY BARRIER RECTIFIER VOLTAGE RANGE 20 - 40 Volts CURRENT 2.0 Amperes |
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