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UTC571のメーカーはHangzhouです、この部品の機能は「Linear Integrated Circuit」です。 |
部品番号 | UTC571 |
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部品説明 | Linear Integrated Circuit | ||
メーカ | Hangzhou | ||
ロゴ | |||
このページの下部にプレビューとUTC571ダウンロード(pdfファイル)リンクがあります。 Total 14 pages
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UTC571
LINEAR INTEGRATED CIRCUIT
COMPANDER
DESCRIPTION
The UTC571 is a versatile low cost dual gain control
circuit in which either channel may be used as a dynamic
range compressor or expandor. Each channel has a full-
wave rectifier to detect the average value of the signal, a
linerarized temperature-compensated variable gain cell,
and an operational amplifier.
The UTC571 is well suited for use in cellular radio and
radio communications systems, modems, telephone, and
satellite broadcast/receive audio systems.
FEATURES
• Complete compressor and expandor in one IChip
DIP-16
•Temperature compensated
•Greater than 110dB dynamic range
APPLICATIONS
• Operates down to 6VDC
•Cellular radio
• System levels adjustable with external components
•High level limiter
• Distortion may be trimmed out
www.DataSheet4U.com• Dynamic noise reduction systems
•Low level expandor—noise gate
•Dynamic filters
•CD Player
• Voltage-controlled amplifier
PIN CONFIGURATION
RECT CAP 1 1
RECT IN 1 2
AG CELL IN 1 3
GND 4
INV.IN 1 5
RES.R3 1 6
OUTPUT 1 7
THD TRIM 1 8
16 RECT CAP 2
15 RECT IN 2
14 AG CELL IN 2
13 VCC
12 INV.IN 2
11 RES.R 3 2
10 OUTPUT 2
9 THD TRIM 2
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UTC571
LINEAR INTEGRATED CIRCUIT
FUNCTION DESCRIPTION
CIRCUIT DESCRIPTION
The UTC571 compandor building blocks, as shown in the block diagram, are a full-wave rectifier, a variable
gain cell, an operational amplifier and a bias system. The arrangement of these blocks in the IC result in a
circuit which can perform well with few external components, yet can be adapted to many diverse applications.
The full-wave rectifier rectifies the input current which flows from the rectifier input, to an internal summing
node which is biased at V REF . The rectified current is averaged on an external filter capacitor tied to the CRECT
terminal, and the average value of the input current controls the gain of the variable gain cell. The gain will thus
be proportional to the average value of the input signal for capacitively-coupled voltage inputs as shown in the
following equation. Note that for capacitively-coupled inputs there is no offset voltage capable of producing a
gain error. The only error will come from the bias current of the rectifier (supplied internally) which is less than
0.1µA.
| VIN − VREF | avg
G ∝ or
R1
| VIN | avg
G∝
R1
The speed with which gain changes to follow changes in input signal levels is determined by the rectifier filter
capacitor. A small capacitor will yield rapid response but will not fully filter low frequency signals. Any ripple on
www.DataSheet4U.comthe gain control signal will modulate the signal passing through the variable gain cell. In an expander or
compressor application, this would lead to third harmonic distortion, so there is a trade-off to be made between
fast attack and decay times and distortion. For step changes in amplitude, the change in gain with time is shown
by this equation.
G(t)=(Ginitial-Gfinal)e-t/τ+Gfinal; τ=10k × CRECT
The variable gain cell is a current-in, current-out device with the ratio IOUT /IIN controlled by the rectifier. IIN is
the current which flows from the DG input to an internal summing node biased at VREF . The following equation
applies for capacitively-coupled inputs. The output current, IOUT , is fed to the summing node of the op amp.
VIN − VREF VIN
IIN =
=
R2 R2
A compensation scheme built into the DG cell compensates for temperature and cancels out odd harmonic
distortion. The only distortion which remains is even harmonics, and they exist only because of internal offset
voltages. The THD trim terminal provides a means for nulling the internal offsets for low distortion operation.
The operational amplifier (which is internally compensated) has the non-inverting input tied to V REF , and the
inverting input connected to the DG cell output as well as brought out externally. A resistor, R 3 , is brought out
from the summing node and allows compressor or expander gain to be determined only by internal components.
The output stage is capable of ±20mA output current. This allows a +13dBm (3.5V RMS ) output into a 300W
load which, with a series resistor and proper transformer, can result in +13dBm with a 600Ω output impedance.
A bandgap reference provides the reference voltage for all summing nodes, a regulated supply voltage for the
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UTC571
LINEAR INTEGRATED CIRCUIT
BASIC CIRCUIT HOOK-UP AND OPERATION
THD TRIM
R3 INVIN
GIN
3.14
R2
20K
RECTIN
2.15
R1
10K
8.9
G
IG
6.11
R3
20K
5.12
VREE
R4 1.8V
30K
VCC PIN 13
GND PIN 4
1.16
CRECT
Figure 2. Chip Block Diagram
OUTPUT
7.10
Figure 2 shows the block diagram of one half of the chip, (there are two identical channels on the IC). The full-
wave averaging rectifier provides a gain control current, IG , for the variable gain (∆G) cell. The output of the DG
cell is a current which is fed to the summing node of the operational amplifier. Resistors are provided to establish
circuit gain and set the output DC bias.
The circuit is intended for use in single power supply systems, so the internal summing nodes must be biased at
www.DataSheet4U.comsome voltage above ground. An internal band gap voltage reference provides a very stable, low noise 1.8V
reference denoted VREF . The non-inverting input of the op amp is tied to VREF , and the summing nodes of the
rectifier and ∆G cell (located at the right of R1 and R2) have the same potential. The THD trim pin is also the VREF
potential.
CIN1
R2
G
R3
VOUT
VIN
CIN2
R1
R4 VREF
NOTE: GAIN=
2R3VIN (avg)
R1R2IB
IB=140A
CRECT
Figure 3. Basic Expander
Figure 3 shows how the circuit is hooked up to realize an expandor. The input signal, VIN is applied to the inputs
of both the rectifier and the ∆G cell. When the input signal drops by 6dB, the gain control current will drop by a
factor of 2, and so the gain will drop 6dB. The output level at VOUT will thus drop 12dB, giving us the desired 2 to 1
expansion.
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ページ | 合計 : 14 ページ | ||
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部品番号 | 部品説明 | メーカ |
UTC571 | Linear Integrated Circuit | Hangzhou |
UTC571M | COMPANDOR | YW |
UTC571N | COMPANDOR | Unisonic Technologies |