TL16C752B
3.3-V DUAL UART WITH 64-BYTE FIFO
SLLS405A – DECEMBER 1999 – REVISED AUGUST 2000
functional block diagram
Modem Control Signals
Control Signals
Status Signals
Divisor
Control
and
Status Block
Bus
Interface
Control Signals
Status Signals
Baud Rate
Generator
UART_CLK
RX
Receiver FIFO
Receiver Block
Logic
Vote
Logic
RX
64-Byte
TX
Transmitter FIFO
64-Byte
Transmitter Block
Logic
TX
NOTE: The vote logic determines whether the RX data is a logic 1 or 0. It takes three samples of the RX line, and uses a majority vote to determine
the logic level received. The vote logic operates on all bits received.
functional description
The TL16C752B UART is pin-compatible with the ST16C2550 UART. It provides more enhanced features. All
additional features are provided through a special enhanced feature register.
The UART will perform serial-to-parallel conversion on data characters received from peripheral devices or
modems and parallel-to-parallel conversion on data characters transmitted by the processor. The complete
status of each channel of the TL16C752B UART can be read at any time during functional operation by the
processor.
The TL16C752B can be placed in an alternate mode (FIFO mode) relieving the processor of excessive software
overhead by buffering received/transmitted characters. Both the receiver and transmitter FIFOs can store up
to 64 bytes (including three additional bits of error status per byte for the receiver FIFO) and have selectable
or programmable trigger levels. Primary outputs RXRDY and TXRDY allow signalling of DMA transfers.
The TL16C752B has selectable hardware flow control and software flow control. Hardware flow control
significantlyreduces software overhead and increases system efficiencyby automatically controlling serial data
flow using the RTS output and CTS input signals. Software flow control automatically controls data flow by using
programmable Xon/Xoff characters.
The UART includes a programmable baud rate generator that can divide the timing reference clock input by a
16
divisor between 1 and (2 –1).
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