that4315 THAT Corporation, that4315 Datasheet - Page 12

• Manufacturer Part Number: that4315
• Description: Pre-trimmed Low-voltage Low-power Analog Engine
• Manufacturer: THAT Corporation

Page 12
Encoder VCA Gain, Encoder Out, Decoder VCA
Gain, and Decoder Out use the equations derived
previously in the section titled “The Mathematics of
Log Based Companding Systems”, and the values in
the column labeled RMS In are derived using the
equation:
and R10, since this sort of break point behavior is
difficult to model in a spreadsheet.
±39 dB are still well within specification, as is the
RMS detector input current, which now varies over
an even smaller range. A maximum decoder output
level of -9 dBV was retained in the event the user de-
cides to use a diode clipper at the output of the VCA
for over-modulation protection.
Other Dynamics Processor
Configurations
4315 so applicable to companding noise reduction
systems also qualify it for application to dynamics
processors of all types. This is even more so when
the application must run from battery power. The
4315 is versatile enough to be used as the heart of a
compressor, expander, noise gate, AGC, de-esser,
frequency-sensitive compressor, and many other dy-
namics processors. It is beyond the scope of this
data sheet to provide specific advice about any of
these functional classes.
RMS
Again, this table does not show the effect of R4
You’ll note that the VCA gain ranges that vary
The same distinguishing features that make the
No Connection
No Connection
No Connection
No Connection
No Connection
In
Pin Name
RMS OUT
VCA OUT
RMS IN
FILTER
Table 4. THAT 4315 pin assignments
=
VCA IN
C
V
GND
EC+
V
EC-
TIME
10
REF
CC
R
Encoder Out
RMS In
20
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com
We refer the interested
Pin Number
10
12
13
14
15
16
11
1
2
3
4
5
6
7
8
9
Copyright © 2009, THAT Corporation
reader to THAT’s applications notebooks volumes 1
and 2, which contain many circuits based on
THAT’s other VCAs and RMS level detectors, but are
largely applicable to the 4315 with only minor varia-
tions. Of course, look for more applications infor-
mation aimed specifically at the 4315 in the future.
Where to go from here
processors is a very intricate art: witness the prolif-
eration of first analog, then digital companding sys-
tems, and the many different dynamics processors
available in the market today. In the applications
section of this data sheet, we offer a few examples of
companders as a starting point only. THAT Corpo-
ration’s applications engineering department is
ready to assist customers with suggestions for tailor-
ing and extending these basic circuits to meet spe-
cific needs.
Package Information
package as shown in Figure 10.
ITEM
Figure 10. QSOP-16 surface mount package drawing
The design of compander systems and dynamics
The THAT 4315 is available in a 16-pin QSOP
J
C
D
G
H
A
B
E
J
I
1
MILLIMETERS
4.80 - 4.98
3.81 - 3.99
5.79 - 6.20
0.20 - 0.30
0.635 BSC
1.35 - 1.75
0.10 - 0.25
0.40 - 1.27
0.19 - 0.25
I
B
C
THAT4315 Pre-trimmed Low-voltage
0-8º
Low-power Analog Engine® IC
D
E
INCHES
0.189 - 0.196
0.150 - 0.157
0.228 - 0.244
0.008 - 0.012
0.025 BSC
0.0532 - 0.0688
0.004 - 0.010
0.016 - 0.050
0.0075 - 0.0098
A
H
G