74HC942 반도체 회로 부품 판매점
full duplex low speed modem
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 National Semiconductor |
January 1988
MM74HC942 300 Baud Modem
General Description
The MM74HC942 is a full duplex low speed modem It pro-
vides a 300 baud bidirectional serial interface for data com-
munication over telephone lines and other narrow band-
width channels It is Bell 103 compatible
The MM74HC942 utilizes advanced silicon-gate CMOS
technology Switched capacitor techniques are used to per-
form analog signal processing
www.DataSheet4U.com MODULATOR SECTION
The modulator contains a frequency synthesizer and a sine
wave synthesizer It produces a phase coherent frequency
shift keyed (FSK) output
LINE DRIVER AND HYBRID SECTION
The line driver and hybrid are designed to facilitate connec-
tion to a 600X phone line They can perform two-to-four-
wire conversion and drive the line at a maximum of 0 dBm
DEMODULATOR SECTION
The demodulator incorporates anti-aliasing filters a receive
filter limiter discriminator and carrier detect circuit The
nine pole receive filter provides 60 dB of transmitted tone
rejection The discriminator is fully balanced for stable
operation
Connection and Block Diagrams
Features
Y Drives 600X at 0 dBm
Y All filters on chip
Y Transmit level adjustment compatible with universal
service order code
Y TTL and CMOS compatible logic
Y All inputs protected against static damage
Y g5V supplies
Y Low power consumption
Y Full duplex answer or originate operation
Y Analog loopback for self test
Y Power down mode
Applications
Y Built-in low speed modems
Y Remote data collection
Y Radio telemetry
Y Credit verification
Y Stand-alone modems
Y Point-of-sale terminals
Y Tone signalling systems
Y Remote process control
TRI-STATE is a registered trademark of National Semiconductor Corp
Dual-In-Line Package
Top View
TL F 5348–1
Order Number MM54HC942 or
MM74HC942
C1995 National Semiconductor Corporation TL F 5348
TL F 5348 – 2
RRD-B30M105 Printed in U S A
Absolute Maximum Ratings (Notes 1 2)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage (VCC)
b0 5 to a7 0V
Supply Voltage (VBB)
a0 5 to b7 0V
DC Input Voltage (VIN)
VBBb1 5 to VCCa1 5V
DC Output Voltage (VOUT)
VBBb0 5 to VCCa0 5V
Clamp Diode Current (IIK IOK)
g20 mA
DC Output Current per pin (IOUT)
g25 mA
DC VCC or GND Current per pin (ICC)
g50 mA
Storage Temperature Range (TSTG)
b65 C to a150 C
Power Dissipation (PD)
(Note 3)
600 mW
www.DataSheet4U.coSmO Package only
Lead Temp (TL)
(Soldering 10 seconds)
500 mW
260 C
Operating Conditions
Supply Voltage (VCC)
Supply Voltage (VBB)
DC Input or Output Voltage
(VIN VOUT)
Operating Temp Range (TA)
MM74HC
Min
45
b4 5
0
b40
Input Rise or Fall Times
(tr tf)
Crystal frequency
Max
55
b5 5
VCC
a85
500
3 579
Units
V
V
V
C
ns
MHz
DC Electrical Characteristics
Symbol
Parameter
Conditions
Te25 C
74HC
Teb40 to 85 C
Typ Guaranteed Limits
Units
VIH Minimum High Level
Input Voltage
3 15 3 15 V
VIL Maximum Low Level
Input Voltage
11 11 V
VOH
Minimum High Level
Output Voltage
VOL Maximum Low Level
Voltage
IIN Maximum Input
Current
VINeVIH or VIL
lIOUTle20 mA
VCC VCCb0 1
l lIOUT e4 0 mA VCCe4 5V
3 98
VINeVIH or VIL
lIOUTle20 mA
l lIOUT e4 0 mA VCCe4 5V
01
0 26
VINeVCC or GND
g0 1
VCCb0 1
37
01
04
g1 0
V
V
V
V
mA
IOZ Output TRI-STATE
Leakage Current
RXD and CD Outputs
ALBeSQTeVCC
g5 mA
ICC IBB
Maximum Quiescent
Supply Current
VIHeVCC VILeGND
ALB or SQTeGND
Transmit Level e b9 dBm
80
12 0
12 0 mA
ICC IBB
Power Down Supply Current
ALBeSQTeVCC
VIHeVCC VILeGND
300 mA
Note 1 Absolute Maximum Ratings are those values beyond which damage to the device may occur
Note 2 Unless otherwise specified all voltages are referenced to ground
Note 3 Power Dissipation temperature derating plastic ‘‘N’’ package b12 mW C from 65 C to 85 C ceramic ‘‘J’’ package b12 mW C from 100 C to 125 C
The demodulator specifications apply to the MM74HC942 operating with a modulator having frequency accuracy phase jitter and harmonic content equal to or
better than the MM74HC942 modulator
2
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full duplex low speed modem - National Semiconductor
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