ST16C2552

6

2.97V TO 5.5V DUAL UART WITH 16-BYTE FIFO

REV. 4.2.1

1.0

PRODUCT DESCRIPTION

The 2552 provides serial asynchronous receive data synchronization, parallel-to-serial and serial-to-parallel

data conversions for both the transmitter and receiver sections. These functions are necessary for converting

the serial data stream into parallel data that is required with digital data systems. Synchronization for the serial

data stream is accomplished by adding start and stops bits to the transmit data to form a data character

(character orientated protocol). Data integrity is ensured by attaching a parity bit to the data character. The

parity bit is checked by the receiver for any transmission bit errors. The electronic circuitry to provide all these

functions is fairly complex especially when manufactured on a single integrated silicon chip. The 2552

represents such an integration with greatly enhanced features. The 2552 is fabricated with an advanced

CMOS process.

The 2552 is an upward solution that provides a dual UART capability with 16 bytes of transmit and receive

FIFO memory, instead of none in the 16C2450. The 2552 is designed to work with high speed modems and

shared network environments, that require fast data processing time. Increased performance is realized in the

2552 by the transmit and receive FIFO’s. This allows the external processor to handle more networking tasks

within a given time. For example, the ST16C2450 without a receive FIFO, will require unloading of the RHR in

93 microseconds (This example uses a character length of 11 bits, including start/stop bits at 115.2 Kbps). This

means the external CPU will have to service the receive FIFO less than every 100 microseconds. However

with the 16 byte FIFO in the 2552, the data buffer will not require unloading/loading for 1.53 ms. This increases

the service interval giving the external CPU additional time for other applications and reducing the overall

UART interrupt servicing time. In addition, the 4 selectable receive FIFO trigger interrupt levels is uniquely

provided for maximum data throughput performance especially when operating in a multi-channel

environment. The FIFO memory greatly reduces the bandwidth requirement of the external controlling CPU,

increases performance, and reduces power consumption.

The 2552 is capable of operation up to 4 Mbps with a 64 MHz clock. With a crystal or external clock input of

14.7456 MHz the user can select data rates up to 921.6 Kbps.

The rich feature set of the 2552 is available through internal registers. Selectable receive FIFO trigger levels,

selectable TX and RX baud rates, and modem interface controls are all standard features. Following a power

on reset or an external reset, the 2552 is software compatible with the 16L2752 and 16C2852.