参数资料
| 型号： | SA575NG |
| 厂商： | ON Semiconductor |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC COMPANDOR 2CHAN GAIN 20-DIP |
| 标准包装： | 18 |
| 类型： | 压缩扩展器 |
| 应用： | 蜂窝式无线电，混频器 |
| 安装类型： | 通孔 |
| 封装/外壳： | 20-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 20-PDIP |
| 包装： | 管件 |
SA575
http://onsemi.com
4
Functional Description
This section describes the basic subsystems and
applications of the SA575 Compandor. More theory of
operation on compandors can be found in AND8159 and
AND8160. The typical applications of the SA575 low
voltage compandor in an Expandor (1:2), Compressor (2:1)
and Automatic Level Control (ALC) function are
explained. These three circuit configurations are shown in
Figures 2, 3, and 4 respectively.
The SA575 has two channels for a complete companding
system. The left channel, A, can be configured as a 1:2
Expandor while the right channel, B, can be configured as
either a 2:1 Compressor, a 1:2 Expandor or an ALC. Each
channel consists of the basic companding building blocks
of rectifier cell, variable gain cell, summing amplifier
and VREF cell. In addition, the SA575 has two additional
high performance uncommitted op amps which can be
utilized for application such as filtering, pre-emphasis/
de-emphasis or buffering.
Figure 5 shows the complete schematic for the
applications demo board. Channel A is configured as an
expandor while channel B is configured so that it can be
used either as a compressor or as an ALC circuit. The
switch, S1, toggles the circuit between compressor and
ALC mode. Jumpers J1 and J2 can be used to either include
the additional op amps for signal conditioning or exclude
them from the signal path. Bread boarding space is
provided for R1, R2, C1, C2, R10, R11, C10 and C11 so that
the response can be tailored for each individual need. The
components as specified are suitable for the complete
audio spectrum from 20 Hz to 20 kHz.
The most common configuration is as a unity gain
non-inverting buffer where R1, C1, C2, R10, C10 and C11 are
eliminated and R2 and R11 are shorted. Capacitors C3, C5,
C8, and C12 are for DC blocking. In systems where the
inputs and outputs are AC coupled, these capacitors and
resistors can be eliminated. Capacitors C4 and C9 are for
setting the attack and release time constant.
C6 is for decoupling and stabilizing the voltage reference
circuit. The value of C6 should be such that it will offer a
very low impedance to the lowest frequencies of interest.
Too small a capacitor will allow supply ripple to modulate
the audio path. The better filtered the power supply, the
smaller this capacitor can be. R12 provides DC reference
voltage to the amplifier of channel B. R6 and R7 provide a
DC feedback path for the summing amp of channel B,
while C7 is a short-circuit to ground for signals. C14 and C15
are for power supply decoupling. C14 can also be
eliminated if the power supply is well regulated with very
low noise and ripple.
Demonstrated Performance
The applications demo board was built and tested for a
frequency range of 20 Hz to 20 kHz with the component
expandor mode, the typical input dynamic range was from
-34 dB to +12 dB where 0 dB is equal to 100 mVRMS. The
typical unity gain level measured at 0 dB @ 1.0 kHz input
was
"0.5 dB and the typical tracking error was "0.1 dB
for input range of -30 to +10 dB.
In the compressor mode, the typical input dynamic range
was from -42 dB to
"18 dB with a tracking error +0.1 dB
and the typical unity gain level was
"0.5 dB.
In the ALC mode, the typical input dynamic range was
from -42 dB to +8.0 dB with typical output deviation of
"0.2 dB about the nominal output of 0 dB. For input
greater than +9.0 dB in ALC configuration, the summing
amplifier sometimes exhibits high frequency oscillations.
There are several solutions to this problem. The first is to
lower the values of R6 and R7 to 20 k
W each. The second
is to add a current limiting resistor in series with C12 at
Pin 13. The third is to add a compensating capacitor of
about 22 to 30 pF between the input and output of summing
amplifier (Pins 12 and 14). With any one of the above
recommendations, the typical ALC mode input range
increased to +18 dB yielding a dynamic range of over
60 dB.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SA576 | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Low power compandor |
| SA57608 | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:One-cell Lithium-ion battery protection with over/undercharge and overcurrent protection |
| SA57608XD | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:One-cell Lithium-ion battery protection with over/undercharge and overcurrent protection |
| SA5760-SM | 制造商:Panasonic Industrial Company 功能描述:SERVICE MANUAL |
| SA576D | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Low Power Compandor |
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