SN54ABT854, SN74ABT854
8-BIT TO 9-BIT PARITY BUS TRANSCEIVERS

SCBS170 - FEBRUARY 1991-REVISED OCTOBER 1992

features

• State-of-the-Art EPIC-IIB ^TM BiCMOS Design Significantly Reduces Power Dissipation
• ESD Protection Exceeds 2000 V Per MIL-STD-883C, Method 3015; Exceeds 200 V Using Machine Model (C = 200 pF, R = 0)
• Latch-Up Performance Exceeds 500 mA Per JEDEC Standard JESD-17
• Typical V_OLP (Output Ground Bounce)
  < 1 V at V_CC = 5 V, T_A = 25°C
• High-Drive Outputs (-32-mA I_OH, 64-mA I_OL)
• Parity Error Flag With Parity Generator/Checker
• Latch for Storage of the Parity Error Flag
• Package Options Include Plastic Small-Outline Packages, Ceramic Chip Carriers, and Standard Plastic and Ceramic 300-mil DIPs

EPIC-IIB is a trademark of Texas Instruments Incorporated.

description

The 'ABT854 8-bit to 9-bit parity transceiver is designed for communication between data buses. When data is transmitted from the A bus to the B bus, a parity bit is generated. When data is transmitted from the B bus to the A bus with its corresponding parity bit, the open-collector parity-error () output indicates whether or not an error in the B data has occurred. The output-enable ( and ) inputs can be used to disable the device so that the buses are effectively isolated. The 'ABT854 provides inverted data at its outputs.

A 9-bit parity generator/checker generates a parity-odd (PARITY) output and monitors the parity of the I/O ports with the flag. The parity-error output can be passed, sampled, stored, or cleared from the latch using the latch-enable () and clear () control inputs. When both and are low, data is transferred from the A bus to the B bus and inverted parity is generated. Inverted parity is a forced error condition that gives the designer more system diagnostic capability.

To ensure the high-impedance state during power up or power down, should be tied to V_CC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

The SN54ABT854 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ABT854 is characterized for operation from -40°C to 85°C.