mc145443dw Freescale Semiconductor, Inc, mc145443dw Datasheet - Page 4

• Manufacturer Part Number: mc145443dw
• Description: Single-chip 300-baud Modem
• Manufacturer: Freescale Semiconductor, Inc

V DD
Positive Power Supply (Pin 6)
V SS
Negative Power Supply (Pin 12)
V AG
Analog Ground (Pin 19)
pin must be decoupled by a capacitor from V AG to V SS and a
capacitor from V AG to V DD . Analog ground is the common
bias line used in the switched capacitor filters, limiter, and
slicer in the demodulation circuitry.
TLA
Transmit Level Adjust (Pin 20)
adjustment range is typically from – 12 dBm to – 9 dBm. (See
Applications Information.)
TxD
Transmit Data (Pin 11)
entered for transmission is modulated using FSK techniques.
A logic high input level represents a mark and a logic low rep-
resents a space (see Table 1).
TxA
Transmit Carrier (Pin 17)
carrier is the digitally synthesized sine wave output of the
modulator derived from a crystal oscillator reference. When a
3.579 MHz crystal is used the frequency outputs shown in
Table 1 apply. (See Applications Information .)
MC145442 MC145443
4
INPUT
TEST
This pin is normally tied to 5.0 V.
This pin is normally tied to 0 V.
Analog ground is internally biased to (V DD – V SS ) / 2. This
This pin is used to adjust the transmit level. Transmit level
Binary information is input to the transmit data pin. Data
This is the output of the line driver amplifier. The transmit
Figure 1. AC Characteristics Evaluation Circuit
V DD
600
600
R TLA
PIN DESCRIPTIONS
OUTPUT
TEST
0.1 F
16
20
17
15
TLA
TxA
RxA2
RxA1
4
3.579 MHz 0.1%
CDT
8
X out
MC145442
MC145443
C CDT
10
X in
FB
RxD
TxD
9
0.1 F
C FB
5
11
D in
D out
NOTE: Actual frequencies may be
ExI
External Input (Pin 18)
driver. It is provided to combine an auxiliary audio signal or
speech signal to the phone line using the line driver. This pin
should be connected to V AG if not used. The average level
must be the same as V AG to maintain proper operation. (See
Applications Information .)
DSI
Driver Summing Input (Pin 1)
ternal signal, such as a DTMF dialer, to the phone line. A
series resistor, R DSI , is needed to define the voltage gain
A V (see Applications Information and Figure 6). When ap-
plying a signal to do DSI pin, the modulator should be
squelched by bringing SQT (Pin 14) to a logic high level. The
voltage gain, A V , is calculated by the formula A V = – R f /R DSI
(where R f
will provide unity gain (A V = – 20 k /20 k
must be left open if not used.
RxD
Receive Data (Pin 6)
resulting from the demodulation of the receive carrier. If no
carrier is present, CD high, the receive data output (RxD) is
clamped high.
Bell 103 (MC145443)
CCITT V.21 (MC145442)
The external input is the non–inverting input to the line
The driver summing input may be used to connect an ex-
The receive data output pin presents the digital binary data
Space
Space
– 20
– 25
– 55
– 60
Data
Data
Mark
Mark
RELATIVE TO THE TRANSMIT CARRIER LEVEL INTO 600
0
crystal is used.
0
MAXIMUM LEVEL OF OUT–OF–BAND ENERGY
20 k ). For example, a 20 k
Table 1. Bell 103 and CCITT V.21
2
Transmit
1070 Hz
1270 Hz
Figure 2. Out–of–Band Energy
1180 Hz
980 Hz
3.4 4
Frequency Characteristics
Originate Mode
Receive
2025 Hz
2225 Hz
1850 Hz
1650 Hz
15 dB/OCTAVE
16
5 Hz assuming 3.579545 MHz
Transmit
2025 Hz
2225 Hz
1850 Hz
1850 Hz
Answer Mode
64
resistor for R DSI
= – 1). This pin
MOTOROLA
Receive
1070 Hz
1270 Hz
1180 Hz
980 Hz
(kHz)
256