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ML145442 Schematic ( PDF Datasheet ) - LANSDALE Semiconductor

Teilenummer ML145442
Beschreibung (ML145442 / ML145443) Single-Chip 300-Baud Modem
Hersteller LANSDALE Semiconductor
Logo LANSDALE Semiconductor Logo 




Gesamt 11 Seiten
ML145442 Datasheet, Funktion
www.DataSheet4U.com
ML145442
ML145443
Single–Chip 300–Baud Modem
Legacy Device: Motorola MC145442B, MC145443B
The ML145442 and ML145443 silicon–gate CMOS single–chip low–speed
modems contain a complete frequency shift keying (FSK) modulator, demod-
ulator, and filter. These devices are compatible with CCITT V.21 (ML145442)
and Bell 103 (ML145443) specifications. Both devices provide full–duplex or
half–duplex 300–baud data communication over a pair of telephone lines.
They also include a carrier detect circuit for the demodulator section and a
duplexer circuit for direct operation on a telephone line through a simple
transformer.
This Device Offers The Following Performance Features:
• ML145442 Compatible with CCITT V.21
• ML145443 Compatible with Bell 103
• Low–Band and High–Band Band–Pass Filters On–Chip
• Simplex, Half–Duplex, and Full–Duplex Operation
• Originate and Answer Mode
• Analog Loopback Configuration for Self Test
• Hybrid Network Function On–Chip
• Carrier Detect Circuit On–Chip
• Adjustable Transmit Level and CD Delay Timing
• On–Chip Crystal Oscillator (3.579 MHz)
• Single +5 V Power Supply Operation
• Internal Mid–Supply Generator
• Power–Down Mode
• Pin Compatible with MM74HC943
• Capable of Driving –9 dBm into a 600 W Load
• Operating Temperature Range = TA –40° to +85°C
20
1
P DIP 20 = RP
PLASTIC DIP
CASE 738
20
1
SOG 20 = -6P
SOG PACKAGE
CASE 751D
CROSS REFERENCE/ORDERING INFORMATION
PACKAGE
MOTOROLA
LANSDALE
P DIP 20 H
SO 20W
P DIP 20 H
SO 20W
MC145442BP
MC145442BDW
MC145443BP
MC145443BDW
ML145442RP
ML145442-6P
ML145443RP
ML145443-6P
Note: Lansdale lead free (Pb) product, as it
becomes available, will be identified by a part
number prefix change from ML to MLE.
PIN ASSIGNMENT
DSI 1
LB 2
CD 3
CDT 4
RxD 5
VDD 6
CDA 7
Xout 8
Xin 9
FB 10
20 TLA
19 VAG
18 Exl
17 TxA
16 RxA1
15 RxA2
14 SQT
13 MODE
12 VSS
11 TxD
Page 1 of 11
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Issue bB






ML145442 Datasheet, Funktion
ML145442, ML145443
www.DataSheet4U.com
LANSDALE Semiconductor, Inc.
GENERAL DESCRIPTION
The ML145442 and ML145443 are full–duplex low–speed
modems. They provide a 300–baud FSK signal for bidirectional
data transmission over the telephone network. They can be operated
in one of four basic configurations as determined by the state of
MODE (pin 13) and LB (pin 2).The normal (non–loopback) and
self test (loopback) modes in both answer and originate modes will
be discussed.
For an originate or channel 1 mode, a logic high level is placed
on MODE (pin 13) and a logic low level is placed on LB (pin 2). In
this mode, transmit data is input on TxD, where it is converted to a
FSK signal and routed through a low–band band–pass filter. The
filtered output signal is then buffered by the Tx op–amp line driver,
which is capable of driving –9 dBm onto a 600line. The receive
signal is connected through a hybrid duplexer circuit on pins 15 and
16, RxA2 and RxA1. The signal then passes through the anti–alias-
ing filter, the sample–and–hold circuit, is switched into the
high–band band–pass filter, and then switched into the AC amplifi-
er circuit. The output of the ac amplifier circuit is routed to the
demodulator circuit and demodulated. The resulting digital data is
then output through RxD (pin 5). The carrier detect circuit receives
its signal from the output of the AC amplifier circuit and goes low
when the incoming signal is detected (see Figure 4a).
In the answer or channel 2 mode, a logic low level is placed on
MODE (pin 13) and on LB (pin 2). In this mode, the data follows
the same path except the FSK signal is routed to the high–band
band–pass filter and the sample–and–hold signal is routed through
the low–band band–pass filter (see Figure 4b).
In the analog loopback originate or channel 1 mode, a logic high
level is placed on MODE (pin 13) and on LB (pin 2). This mode is
used for a self check of the modulator, demodulator, and low–band
pass–band filter circuit. The modulator side is configured exactly
like the originate mode above except the line driver output (TxA,
pin 17) is switched to the negative input of the hybrid op–amp. The
RxA2 input pin is open in this mode and the non–inverting input of
the hybrid circuit is connected to VAG. The sample–and–hold out-
put bypasses the filter so that the demodulator receives the modu-
lated Tx data (see Figure 4c). This test checks all internal device
components except the high–band band–pass filter, which can be
checked in the answer or channel 2 mode test.
In the analog loopback or channel 2 mode, a logic low level is
placed on MODE (pin 13) and a logic high level on LB (pin 2).
This mode is used for a self check of the modulator, demodulator,
and high–band pass–band filter circuit. This configuration is exact-
ly like the originate loopback mode above, except the signal is rout-
ed through the high–band pass–band filter (see Figure 4d).
Page 6 of 11
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Issue b

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