[ /Title (CD74HC652, CD74HCT652)

/Subject (High-Speed CMOS Logic Octal-Bus

Transceiver/Registers, Three-State)

/Author ()

/Keywords ()

/Creator ()

/DOCINFO pdfmark

[ /PageMode /UseOutlines

/DOCVIEW pdfmark

Features

• CD74HC652, CD74HCT652 . . . . . . . . . . . Non-Inverting

• Independent Registers for A and B Buses

• Three-State Outputs

• Drives 15 LSTTL Loads

• Typical Propagation Delay = 12ns at VCC = 5V,CL = 15pF

• Fanout (Over Temperature Range)

- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads

- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads

• Wide Operating Temperature Range . . . -55oC to 125oC

• Balanced Propagation Delay and Transition Times

• Significant Power Reduction Compared to LSTTL

Logic ICs

• Alternate Source is Philips

• HC Types

- 2V to 6V Operation

- High Noise Immunity: NIL = 30%, NIH = 30% of VCC

at VCC = 5V

• HCT Types

- 4.5V to 5.5V Operation

- Direct LSTTL Input Logic Compatibility,

VIL= 0.8V (Max), VIH = 2V (Min)

- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

Description

The CD74HC652 and CD74HCT652 three-state, octal-bus

transceiver/registers use silicon-gate CMOS technology to

achieve operating speeds similar to LSTTL with the low power

consumption of standard CMOS integrated circuits. The

CD74HC652 and CD74HCT652 have non-inverting outputs.

These devices consists of bus transceiver circuits, D-type flipflops,

and control circuitry arranged for multiplexed

transmission of data directly from the data bus or from the

internal storage registers. Output Enables OEAB and OEBA

are provided to control the transceiver functions. SAB and

SBA control pins are provided to select whether real-time or

stored data is transferred. The circuitry used for select control

will eliminate the typical decoding glitch that occurs in a

multiplexer during the transition between stored and real-time

data. A LOW input level selects real-time data, and a HIGH

selects stored data. The following examples demonstrates the

four fundamentals bus-management functions that can be

performed with the octal-bus transceivers and registers.

Data on the A or B data bus, or both, can be stored in the

internal D flip-flops by low-to-high transitions at the appropriate

clock pins (CAB or CBA) regardless of the select of the control

pins. When SAB and SBA are in the real-time transfer mode, it

is also possible to store data without using the D-type flip-flops

by simultaneously enabling OEAB and OEBA. In this

configuration, each output reinforces its input. Thus, when all

other data sources to the two sets of bus lines are at high

impedance, each set of bus lines will remain at its last state.