3.3-V/5-V Dual Universal Asynchronous Receiver/Transmitter

The TL28L92 operates at 3.3V or 5V supply with

added features and deeper FIFOs. The configuration on power-up is 16 character

receiver, 16 character transmit FIFOs, watchdog timer for each receiver, mode

register 0 is added, extended baud rate and overall faster speeds, programmable

receiver and transmitter interrupts.

Pin programming allows the device to operate with

either the Motorola or Intel bus interface. The bit 3 of the MR0A register allows

the device to operate in an 8 byte FIFO mode.

The Texas Instruments TL28L92 Dual

Universal Asynchronous Receiver/Transmitter (DUART) is a single-chip CMOS-LSI

communications device that provides two full-duplex asynchronous

receiver/transmitter channels in a single package. the device interfaces directly

with microprocessors, and can be used in a polled or interrupt driven system with

modem and DMA interface.

The operating mode and data format of

each channel can be programmed independently. Additionally, each receiver and

transmitter can select an operating speed as one of 28 fixed baud rates; a 16× clock

derived from a programmable counter/timer, or an external 1× or 16× clock. The baud

rate generator and counter/timer can operate directly from a crystal or from

external clock inputs. The ability to independently program the operating speed of

the receiver and transmitter make the DUART particularly attractive for dual-speed

channel applications such as clustered terminal systems.

Each receiver and transmitter is

buffered by 8 or 16 character FIFOs to minimize the potential of receiver overrun,

transmitter underrun, and to reduce interrupt overhead in interrupt driven systems.

In addition, a flow control capability is provided via RTS/CTS signaling to disable

a remote transmitter when the receiver buffer is full. Also provided on the TL28L92

is a multipurpose 7-bit input port and a multipurpose 8-bit output port. These can

be used as general purpose I/O ports or can be assigned specific functions (such as

clock inputs or status/interrupt outputs) under program control.

The TL28L92 is available now in 44-pin

QFP (FR).