Integrated Asynchronous Communications

Element

Consists of Four Improved TL16C550 ACEs

Plus Steering Logic

In FIFO Mode, Each ACE Transmitter and

Receiver Is Buffered With 16-Byte FIFO to

Reduce the Number of Interrupts to CPU

In TL16C450 Mode, Hold and Shift

Registers Eliminate Need for Precise

Synchronization Between the CPU and

Serial Data

Up to 16-MHz Clock Rate for up to 1-Mbaud

Operation

Programmable Baud Rate Generators

Which Allow Division of Any Input

Reference Clock by 1 to (216

−
1) and

Generate an Internal 16 × Clock

Adds or Deletes Standard Asynchronous

Communication Bits (Start, Stop, and

Parity) to or From the Serial Data Stream

Independently Controlled Transmit,

Receive, Line Status, and Data Set

Interrupts

Fully Programmable Serial Interface

Characteristics:

− 5-, 6-, 7-, or 8-Bit Characters

− Even-, Odd-, or No-Parity Bit

− 1-, 1 1/2-, or 2-Stop Bit Generation

− Baud Generation (DC to 1-Mbit Per

Second)

False Start Bit Detection

Complete Status Reporting Capabilities

Line Break Generation and Detection

Internal Diagnostic Capabilities:

− Loopback Controls for Communications

Link Fault Isolation

− Break, Parity, Overrun, Framing Error

Simulation

Fully Prioritized Interrupt System Controls

Modem Control Functions (CTS, RTS, DSR,

DTR, RI, and DCD)

3-State Outputs Provide TTL Drive

Capabilities for Bidirectional Data Bus and

Control Bus

description

The TL16C554 and the TL16C554I are enhanced quadruple versions of the TL16C550B asynchronous

communications element (ACE). Each channel performs serial-to-parallel conversion on data characters

received from peripheral devices or modems and parallel-to-serial conversion on data characters transmitted

by the CPU. The complete status of each channel of the quadruple ACE can be read at any time during functional

operation by the CPU. The information obtained includes the type and condition of the operation performed and

any error conditions encountered.

The TL16C554 and the TL16C554I quadruple ACE can be placed in an alternate FIFO mode, which activates

the internal FIFOs to allow 16 bytes (plus three bits of error data per byte in the receiver FIFO) to be stored in

both receive and transmit modes. To minimize system overhead and maximize system efficiency, all logic is on

the chip. Two terminal functions allow signaling of direct memory access (DMA) transfers. Each ACE includes

a programmable baud rate generator that can divide the timing reference clock input by a divisor between 1 and

(216−1).

The TL16C554 and the TL16C554I are available in a 68-pin plastic-leaded chip-carrier (PLCC) FN package and

in an 80-pin (TQFP) PN package.