73K222AU-IH 查看數據表（PDF） - TDK Corporation

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73K222AU-IH

Single-Chip Modem Modem with UART

TDK Corporation 

73K222AU

Single-Chip Modem

with UART

FUNCTIONAL DESCRIPTION

The 73K222AU integrates an industry standard

8250/16C450 UART function with the modem

capability provided by the 73K222L single chip

modem IC. The 73K222AU is designed specifically

for integral microprocessor bus intelligent modem

products. These designs typically require the

standard 8250 or higher speed 16450 UART to

perform parallel-to-serial and serial-to-parallel

conversion process necessary to interface a parallel

bus with the inherently serial modem function. The

73K222AU provides a highly integrated design

which can eliminate multiple components in any

integral bus modem application, and is ideal for

internal PC modem applications.

The 73K222AU includes two possible operating

modes. In the dual-port mode, the device is suitable

for conventional plug-in modem card designs which

use a separate local microprocessor for command

interpretation and control of the modem function. In

this mode, a dedicated microcontroller

communicates with the 73K222AU using a separate

serial command port. In the single-port mode the

main CPU can control both the UART and modem

function using the parallel data bus. This allows very

efficient modem design with no local microprocessor

required for dedicated applications such as laptop

PC’s or specialized terminals.

To make designs more space efficient, the

73K222AU includes the 2-wire to 4-wire hybrid

drivers, off-hook relay driver, and an audio monitor

output with software volume control for audible call

progress monitoring. As an added feature the UART

function can be used independent of the modem

function, providing an added asynchronous port in a

typical PC application with no additional circuitry

required.

UART FUNCTION (16C450)

The UART section of the 73K222AU is completely

compatible with the industry standard 16C450 and

the 8250 UART devices. The bus interface is

identical to the 16450, except that only a single

polarity for the control signals is supported. The

register contents and addresses are also the same

as the 16C450. To insure compatibility with all

existing releases of the 8250 UART design, external

circuitry normally used in PC applications to emulate

8250B or 8250A interrupt operation has been

included on the 73K222AU. A select line is then

provided to enable the desired interrupt operation.

The UART used in the 73K222AU can be used with

faster bus read and write cycles than a conventional

16C450 UART. This allows it to interface directly

with higher clock rate microprocessors with no need

for external circuitry to generate wait states.

The primary function of the UART is to perform

parallel-to-serial conversion on data received from

the CPU and serial-to-parallel conversion on data

received from the internal modem or an external

device. The UART can program the number of bits

per character, parity bit generation and checking,

and the number of stop bits. The UART also

provides break generation and detection, detection

of error conditions, and reporting of status at any

time. A prioritized maskable interrupt is also

provided.

The UART block has a programmable baud rate

generator which divides an internal 1.8432 MHz

clock to generate a clock at 16 x the data rate. The

data rate for the transmit and receive sections must

be the same. For DPSK modulation, the data rate

must be 1200 Hz or 600 Hz. For FSK modulation,

the data rate must be 300 Hz or less. The baud

generator can create a clock that supports digital

transfer at up to 115.2 kHz. The output of the baud

generator can be made available at the CLK pin

under program control.

MODEM FUNCTION (73K222AL)

The modem section of the 73K222AU provides all

necessary analog functions required to create a

single chip Bell 212A/103 and CCITT V.22/V.21

modem, controlled by the system CPU or a local

dedicated microprocessor. Asynchronous 1200 bit/s

DPSK (Bell 212A and V.22) and 300 baud FSK (Bell

103 and V.21) modes are supported.

The modem portion acts as a peripheral to the

microprocessor. In both modes of operation, control

information is stored in register memory at specific

address locations. In the single-port mode, the

modem section can be controlled through the

16C450 interface, with no external microcontroller

required. The primary analog blocks are the DPSK

modulator/demodulator, the FSK modulator/

demodulator, the high and low band filters, the AGC,

the special detect circuitry, and the DTMF tone

generator. The analog functions are performed with

switched capacitor technology.

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