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PDF ML145442 Data sheet ( Hoja de datos )
| Número de pieza | ML145442 | |
| Descripción | (ML145442 / ML145443) Single-Chip 300-Baud Modem | |
| Fabricantes | LANSDALE Semiconductor | |
| Logotipo |  |
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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
1 page  
LANSDALE Semiconductor, Inc.
www.DataSheet4U.com
ML145442, ML145443
RxA2, RxA1
Receive Carrier (Pins 15, 16)
The receive carrier is the FSK input to the demodulator through
the receive band–pass filter. RxA1 is the non–inverting input and
RxA2 is the inverting input of the receive hybrid (duplexer) oper-
ational amplifier.
LB
Analog Loopback (Pin 2)
When a high level is applied to this pin (SQT must be low), the
analog loopback test is enabled. The analog loopback test con-
nects the TxA pin to the RxA2 pin and the RxA1 to analog
ground. In loopback, the demodulator frequencies are switched to
the modulation frequencies for the selected mode. (See Tables 1
and 2 and Figures 4c and 4d.)
When LB is connected to analog ground (VAG), the modulator
generates an echo cancellation tone of 2100 Hz for ML145442
CCITT V.21 and 2225 Hz for ML145443 Bell 103 systems. For
normal operation, this pin should be at a logic low level (VSS).
The power–down mode is enabled when both LB and SQT are
connected to a logic high level (see Table 2).
Table 2. Functional Table
MODE SQT
Pin 13 Pin 14
LB
Pin 2
Operating Mode
10
0 Originate Mode
00
0 Answer Mode
X 0 VAG (VDD/2) Echo Tone
X0
1 Analog Loopback
X1
0 Squelch Mode
X 1 VAG (VDD/2) Squelch Mode
X1
1 Power Down
MODE
Mode (Pin 13)
This input selects the pair of transmit and frequencies used dur-
ing modulation and demodulation. When a logic high level is
placed on this input, originate (Bell) or channel 1(CCITT) is
selected. When a low level is placed on this input, answer (Bell) or
channel 2 (CCITT) is selected. (See Tables 1 and 2 and Figure 4.)
CDT
Carrier Detect Timing (Pin 4)
A capacitor on this pin to VSS sets the amount of time the car-
rier must be present before CD goes low (see Legacy Applications
Information for the capacitor values).
CD
Carrier Detect Output (Pin 3)
This output is used to indicate when a carrier has been sensed
by the carrier detect circuit. This output goes to a logic low level
when a valid signal above the maximum threshold level (defined
by CDA, pin 7) is maintained on the input to the hybrid circuit
longer then the response (defined by CDT, pin 4). This pin is held
at the logic low level until the signal falls below the maximum
threshold level for longer than the turn off time. (See Legacy
Applications Information and Figure 5.)
CDA
Carrier Detect Adjust (Pin 7)
An external voltage may be applied to this pin to adjust the car-
rier detect threshold. The threshold hysteresis is internally fixed at
3 dB (see Legacy Applications Information).
Xout, Xin
Crystal Oscillator (Pins 8, 9)
A crystal reference oscillator is formed when a 3.579 MHz
crystal is connected between these two pins. Xout (pin 8) is the
output of the oscillator circuit, and Xin (pin 9) is the input to the
oscillator circuit. When using an external clock, apply the clock to
the Xin (pin 9) pin and leave Xout (pin 8) open. An internal 10
MΩ resistor and internal capacitors, typically 10 pF on Xin and
16 pF on Xout, allow the crystal to be connected without any
other external components. Printed circuit board layout should
keep external stray capacitance to a minimum.
FB
Filter Bias (Pin 10)
This is the negative input to the AC amplifier. In normal opera-
tion, this pin is connected to analog ground through a 0.1µF
bypass capacitor in order to cancel the input offset voltage of the
limiter. It has a nominal input impedance of 16 kΩ (see Figure 3).
SQT
Transmit Squelch (Pin 14)
When this input pin is at a logic high level, the modulator is
disabled. The line driver remains active if LB is at a logic low
level (see Table 2).
When both LB and SQT are connected to a logic high level (see
Table 2), the entire chip is in a power down state and all circuitry
except the crystal oscillator is disabled. Total power supply cur-
rent decreases from 10 mA (max) to 300 µA (max).
FROM
BAND–PASS
FILTER
+
–
490 kΩ
16 kΩ
10 FB
0.1 µF
TO
CARRIER DETECT CIRCUIT
AND DEMODULATOR
Figure 3. AC Amplifier Circuit
Page 5 of 11
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Issue b
5 Page 
LANSDALE Semiconductor, Inc.
www.DataSheet4U.com
Legacy Applications Information
ML145442, ML145443
Lansdale Semiconductor reserves the right to make changes without further notice to any products herein to improve reliabil-
ity, function or design. Lansdale does not assume any liability arising out of the application or use of any product or circuit
described herein; neither does it convey any license under its patent rights nor the rights of others. “Typical” parameters which
may be provided in Lansdale data sheets and/or specifications can vary in different applications, and actual performance may
vary over time. All operating parameters, including “Typicals” must be validated for each customer application by the cus-
tomer’s technical experts. Lansdale Semiconductor is a registered trademark of Lansdale Semiconductor, Inc.
Page 11 of 11
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Issue b
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet ML145442.PDF ] | |
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