74LCX646 Datasheet | STMicroelectronics

DESCRIPTION The 74LCX646 is a low voltage CMOS OCTAL BUS TRANSCEIVER AND REGISTER (3-STATE) fabricated with sub-micron silicon gate and double-layer metal wiring C2MOS technology. It is ideal for low power and high speed 3.3V applications; it can be interfaced to 5V signal environment for both inputs and outputs. PIN CONNECTION AND IEC LOGIC SYMBOLS This device consists of bus transceiver circuits with 3 state, D-type flip-flops, and control circuitry arranged for multiplexed transmission of data directly from the input bus or from the internal registers. Data on the A or B bus will be clocked into register on the low to high transition of the appropriate clock pin (Clock AB or Clock BA). Enable (G) and direction (DIR) pins are provided to control the transceiver functions. In the transceiver mode, data present at the high-impedance port may be stored in either register or in both. The select controls (Select AB select BA) can multiplex stored and real time (transparent mode) data. The direction control determines which bus will receive data when enable G is active (low). In the isolation mode September 2001 1/13 M74LCX646 (enable G high), "A" data may be stored in one register and/or "B" data may be stored in the other register. When an output function is disabled, the input function is still enabled and may be used to store and transmit data. Only one of the two buses, A or B, may be driven at a time. It has same speed performance at 3.3V than 5V INPUT AND OUTPUT EQUIVALENT CIRCUIT AC/ACT family, bined with a lower power consumption. All inputs and outputs are equipped with protection circuits against static discharge, giving them 2KV ESD immunity and transient excess voltage. PIN DESCRIPTION PIN No 1 2 3 4, 5, 6, 7, 8, 9, 10, 11 20, 19, 18, 17, 16, 15, 14, 13 21 22 23 12 24 SYMBOL CLOCK AB (CAB) SELECT AB (SAB) DIR A1 to A8 B1 to B8 G SELECT BA (SBA) CLOCK BA (CBA) GND VCC NAME AND FUNCTION A to B Clock Input (LOW to HIGH, Edge-Triggered) Select A to B...