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參數(shù)資料
| 型號(hào)： | MC145442B |
| 廠商： | Motorola, Inc. |
| 英文描述： | Single-Chip 300-Baud Modem |
| 中文描述： | 單芯片300波特調(diào)制解調(diào)器 |
| 文件頁(yè)數(shù)： | 6/12頁(yè) |
| 文件大?。?/td> | 111K |
| 代理商： | MC145442B |
MC145442B
MC145443B
6
MOTOROLA
GENERAL DESCRIPTION
The MC145442B and MC145443B are full–duplex low–
speed modems. They provide a 300–baud FSK signal for bi-
directional 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 buff-
ered by the Tx op–amp line driver, which is capable of driving
–9 dBm onto a 600
line. 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–aliasing
filter, the sample–and–hold circuit, is switched into the high–
band band–pass filter, and then switched into the ac amplifier
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 in-
put of the hybrid op–amp. The RxA2 input pin is open in this
mode and the non–inverting input of the hybrid circuit is con-
nected to VAG. The sample–and–hold output bypasses the
filter so that the demodulator receives the modulated Tx data
(see Figure 4c). This test checks all internal device compo-
nents 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 exactly like the originate loopback mode
above, except the signal is routed through the high–band
pass–band filter (see Figure 4d).
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MC145443B | Single-Chip 300-Baud Modem |
| MC145442BP | Single-Chip 300-Baud Modem |
| MC145443BDW | Single-Chip 300-Baud Modem |
| MC145443BP | Single-Chip 300-Baud Modem |
| MC145442DW | Single-Chip 300-Baud Modem |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MC145443P | 制造商:Motorola Inc 功能描述: |
| MC145446AFW | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Motorola Inc 功能描述: 制造商:MOTOROLA 功能描述: |
| MC145447DW | 制造商:Motorola Inc 功能描述:CALLER NUMBER ID CIRCUIT, 16 Pin, Plastic, SOP |
| MC145447DWR2 | 制造商:Motorola Inc 功能描述:TELEPHONE MULTIFUNCTION CKT, 16 Pin Plastic SOP |
| MC145447P | 制造商:Motorola Inc 功能描述: |
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