8-Bit to 9-Bit Parity Bus Transceivers

The 'ABT833 8-bit to 9-bit parity transceivers are 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 'ABT833 provide true data at their 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. is clocked into the register on the rising edge of the clock (CLK) input. The error flag register is cleared with a low pulse on the clear () input. 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 VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

The SN54ABT833 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ABT833 is characterized for operation from -40°C to 85°C.