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.