4305-DEMO THAT Corporation, 4305-DEMO Datasheet - Page 3

• Manufacturer Part Number: 4305-DEMO
• Description: Audio Modules & Development Tools Low-Cost Dynamics Processor Demo Board
• Manufacturer: THAT Corporation

Specifications of 4305-DEMO

• Description/function: Audio DSPs
• Operating Supply Voltage: 15 V
• Product: Audio Modules
• For Use With/related Products: THAT4305
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Document 600067 Rev 01
THAT Corporation's proven exponentially controlled
Blackmer® Voltage-Controlled Amplifier (VCA) and
log-responding RMS-Level Detector building blocks
in a small package optimized for low cost designs.
The part is fabricated using a proprietary, fully
complementary, dielectric-isolation process. This
process produces very high-quality bipolar transis-
tors (both NPNs and PNPs) with unusually low
collector- substrate capacitances. The 4305 takes
advantage of these devices to deliver wide bandwidth
and excellent audio performance while consuming
very low current and operating over a wide range of
power supply voltages.
and RMS Detector, we refer the interested reader to
THAT Corporation's data sheets on the 2180-Series
Parameter
Rectifier Balance
Timing Current
Filtering Time Constant
Output Tempco
Load Resistance
Capacitive Load
VCA In
The THAT 4305 Dynamics Processor combines
For details of the theory of operation of the VCA
100p
10u
C2
C5
Control Voltage
20k
6k8
R3
R4
Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
15
ΔE
Electrical Characteristics (con’t)
Symbol
VCA In
Ec+
O
Ec-
/ΔT
R
C
I
τ
11
12
T
+15V
-15V
L
L
Vee
Vcc
CHIP
9
8
Gnd
VCA Out
6
U1A
THAT4305
Theory of Operation
Figure 2. Simplified application circuit
13
-250mV < V
20k
R2
22p NPO
Ref T
±7.5μA DC
Conditions
C3
U2
CHIP
OUTRMS
= 27 ºC
< +250mV
VCAs and the 2252 RMS Level Detector. Theory of the
interconnection of exponentially controlled VCAs and
log-responding level detectors is covered in THAT
Corporation's application note AN101A, The Mathe-
matics of Log-Based Dynamic Processors.
The VCA - in Brief
ration's highly successful complementary log-antilog
gain cell topology (the Blackmer® VCA) as used in
THAT 2180-Series IC VCAs. VCA symmetry is
trimmed
distortion. No external adjustment is allowed.
(pin 15). This pin is a virtual ground with a small dc
offset, so in normal operation an input voltage is
VCA Out
IN
RMS In
The VCA in the 4305 is based on THAT Corpo-
Input signals are currents in the VCA's VCA
10u
C1
during
Min
2
-
-
5k1
R1
+15V
wafer
3467 X C
2
10u
2
C4
+0.33
Typ
7.5
THAT4305
±1
U1B
RMS In
RMS Out
4
probe
TIME
CT
10u
C
Max
150
TIME
±3
-
-
5
for
R5
RMS Out
2k
Page 3 of 20
minimum
Units
%/ºC
kΩ
dB
μA
pF
IN
s
pin