8251A © 2013 Rochester Electronics, LLC. All Rights Reserved 05092013 8251A PROGRAMMABLE COMMUNICATION INTERFACE ■■Synchronous and Asynchronous Operation ■■Synchronous 5-8 Bit Characters; Internal or External Character Synchronization; Automatic Sync Insertion ■■Asynchronous Baud Rate - DC to 19.2K Baud ■■Full-Duplex, Double-Buffered Transmitter and Receiver ■■Asynchronous 5-8 Bit Characters; Clock Rate - 1, 16, or 64 Times Baud Rate; Break Character Generation; 1, 1 1/2, or 2 Stop Bits; False Start Bit Detection; Automatic Break Detect and Handling ■■Error Detection - Parity, Overrun and Framing ■■Synchronous Baud Rate - DC to 64K Baud ■■All Inputs and Outputs are TTL Compatible ■■Compatible with an Extended Range of Intel Microprocessors ■■28-Pin DIP Package ■■Available in EXPRESS and Military Versions The 8251A is the industry standard Universal Synchronous/Asynchronous Receiver/Transmitter (USART) designed for data communications with microprocessor families such as MCS-48, 80, 85, and iAPX 86, 88. The 8251A is used as a peripheral device and is programmed by the CPU to operate using virtually any serial data transmission technique presently in use (including IBM “bi-sync”). The USART accepts data characters from the CPU in parallel format and then converts them into a continuous serial data stream for transmission. Simultaneously, it can receive serial data streams and convert them into parallel data characters for the CPU. The USART will signal the CPU whenever it can accept a new character for transmission or whenever it has received a character for the CPU. The CPU can read the complete status of the USART at any time. These include data transmission errors and control signals such as SYNDET, TxEMPTY. The chip is fabricated using Intel’s high performance HMOS technology. For complete Rochester ordering guide, please refer to page 2. Please contact factory for specific package and specification availability. Rochester Electronics guarantees performance of its semiconductor products to the original OEM specifications. “Typical” values are for reference purposes only. Certain minimum or maximum ratings may be based on product characterization, design, simulation, or sample testing. Rochester Electronics reserves the right to make changes without further notice to any specification herein. Specification Number 8251A-CI (I) REV C Page 1 of 11 8251A Rochester Ordering Guide *Most products can also be offered as RoHS compliant, designated by a –G suffix. Please contact factory for more information. Rochester Part Number Intel Part Number Package Temperature D8251A D8251A CDIP-28 0° to +70°C ID8251A ID8251A CDIP-28 -40° to +85°C LD8251A LD8251A CDIP-28 -40° to +85°C P8251A P8251A PDIP-28 0° to +70°C QD8251A QD8251A CDIP-28 0° to +70°C QP8251A QP8251A PDIP-28 0° to +70°C TD8251A TD8251A CDIP-28 -40° to +85°C Specification Number 8251A-CI (I) REV C Page 2 of 11 8251A Specification Number 8251A-CI (I) REV C Page 3 of 11 8251A Specification Number 8251A-CI (I) REV C Page 4 of 11 8251A Specification Number 8251A-CI (I) REV C Page 5 of 11 8251A Specification Number 8251A-CI (I) REV C Page 6 of 11 8251A Specification Number 8251A-CI (I) REV C Page 7 of 11 8251A Specification Number 8251A-CI (I) REV C Page 8 of 11 8251A Specification Number 8251A-CI (I) REV C Page 9 of 11 8251A Specification Number 8251A-CI (I) REV C Page 10 of 11 8251A Rochester Electronics guarantees performance of its semiconductor products to the original OEM specifications. “Typical” values are for reference purposes only. Certain minimum or maximum ratings may be based on product characterization, design, simulation, or sample testing. Rochester Electronics reserves the right to make changes without further notice to any specification herein. Specification Number 8251A-CI (I) REV C Page 11 of 11