Low Bit Rate Voiceband Encoders/Decoders
Semiconductor
March 1993
Features
• All Digital
• Requires Few External Parts
ED
ND
ME
M
S
Continuously Variable Slope
Delta-Demodulator (CVSD)
CO
IGN
E
R
ES
OT
W D
Description
N
NE
OR
F
The HC-55536 is a CMOS integrated circuit used to convert
serial NRZ digital data to an analog (voice) signal. Conver-
sion is by delta demodulation, using the Continuously
Variable Slope (CVSD) method of demodulation.
While signals are compatible with other CVSD circuits, the
internal design is unique. The analog loop filters have been
replaced by digital filters which use very low power and
require no external timing components. This digital approach
allows inclusion of many desirable features, which otherwise
would be difficult to implement. The device is usable from
9Kbits/s to above 64kbits/s, and may be easily configured
with the HC-55564 CVSD for a complete transmit/receive
voice channel.
HC-55536
• Low Power Drain: 1.5mW from Single 3V to 6V Supply
• Time Constants Determined by Clock Frequency; No
Calibration or Drift Problems; Automatic Offset
Adjustment
• Filter Reset by Digital Control
• Automatic Overload Recovery
• Automatic “Quiet” Pattern Generation
Applications
• Voice Decoder for Digital Systems and Speech
Syntheses
• Voicemail
• Audio Manipulations; Delay Lines, Echo Generation/
Suppression, Special Effects, etc.
• Pagers/Satellites
Ordering Information
PART
NUMBER
HC1-55536-5
HC1-55536-9
HC3-55536-5
HC3-55536-9
TEMP.
RANGE (
o
C)
0 to 75
-40 to 85
0 to 75
-40 to 85
PACKAGE
14 Ld CERDIP
14 Ld CERDIP
14 Ld PDIP
14 Ld PDIP
PKG. NO.
Pinout
HC-55536
(PDIP, CERDIP)
TOP VIEW
Functional Diagram
(13) (12)
FORCE ZERO
DIGITAL IN
VDD 1
NC 2
AOUT 3
NC 4
NC 5
NC 6
NC 7
14 NC
13 FZ
12 DIGITAL INPUT
11 NC
10 NC
9 CLOCK
8 DIGITAL GND
Z
O
10 BIT
DAC
10
SIGNAL
ESTIMATE
DIGITAL FILTER
1.0msec
3 BIT
SHIFT
REGISTER
1
SYLLABIC
DIGITAL
FILTER
4.0msec
6
DIGITAL
MODULATOR
+1
6
A
OUT
(3)
CLOCK
(9)
V
DD
(1)
DIGITAL GND
(8)
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures.
Copyright
©
Harris Corporation 1997
File Number
2888.1
4-252
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