SN74F657

SN74F657 OCTAL TRANSCEIVER WITH PARITY GENERATOR/CHECKER AND 3-STATE OUTPUTS SDFS027A – D3217, JANUARY 1989 – REVISED OCTOBER 1993 Combines ′F245 and ′F280B Functions in One Package High-Impedance N-P-N Inputs for Reduced Loading (70 µA in Low and High States) High Output Drive and Light Bus Loading 3-State B Outputs Sink 64 mA and Source 15 mA Input Diodes for Termination Effects Package Options Include Plastic Small-Outline Packages and Standard Plastic 300-mil DIPs description The SN74F657 contains eight noninverting buffers with 3-state outputs and an 8-bit parity generator/checker. It is intended for bus-oriented applications. The buffers have a specified current sinking capability of 24 mA at the A port and 64 mA at the B port. DW OR NT PACKAGE (TOP VIEW) T/R 1 A1 2 A2 3 A3 4 A4 5 A5 6 VCC 7 A6 8 A7 9 A8 10 ODD/EVEN 11 ERR 12 24 OE 23 B1 22 B2 21 B3 20 B4 19 GND 18 GND 17 B5 16 B6 15 B7 14 B8 13 PARITY The transmit/receive (T/R) input determines the direction of the data flow through the bidirectional transceivers. When T/R is high, data is transmitted from the A port to the B port. When T/R is low, data is received at the A port from the B port. When the output enable (OE) input is high, both the A and B ports are placed in a high-impedance state (disabled). The ODD/EVEN input allows the user to select between odd or even parity systems. When transmitting from A port to B port (T/R high), PARITY is an output from the generator/checker. When receiving ...