ON Semiconductort
Low−Voltage CMOS Octal
Transceiver/Registered
Transceiver
With 5 V−Tolerant Inputs and Outputs
(3−State, Non−Inverting)
The MC74LCX646 is a high performance, non−inverting octal
transceiver/registered transceiver operating from a 2.3 to 3.6 V supply.
High impedance TTL compatible inputs significantly reduce current
loading to input drivers while TTL compatible outputs offer improved
switching noise performance. A VI specification of 5.5 V allows
MC74LCX646 inputs to be safely driven from 5 V devices. The
MC74LCX646 is suitable for memory address driving and all TTL
level bus oriented transceiver applications.
Data on the A or B bus will be clocked into the registers as the
appropriate clock pin goes from a LOW−to−HIGH logic level. Output
Enable (OE) and DIR pins are provided to control the transceiver
outputs. In the transceiver mode, data present at the high impedance
port may be stored in either the A or the B register or in both. The
select controls (SBA, SAB) can multiplex stored and real−time
(transparent mode) data. The direction control (DIR) determines
which bus will receive data when the enable OE is active LOW. In the
isolation mode (OE HIGH), A data may be stored in the B register or B
data may be stored in the A register. Only one of the two buses, A or B,
may be driven at one time.
• Designed for 2.3 to 3.6 V VCC Operation
• 5 V Tolerant − Interface Capability With 5 V TTL Logic
• Supports Live Insertion and Withdrawal
• IOFF Specification Guarantees High Impedance When VCC = 0 V
• LVTTL Compatible
• LVCMOS Compatible
• 24 mA Balanced Output Sink and Source Capability
• Near Zero Static Supply Current in All Three Logic States (10 μA)
Substantially Reduces System Power Requirements
• Latchup Performance Exceeds 500 mA
• ESD Performance: Human Body Model >2000 V;
Machine Model >200 V
MC74LCX646
LOW−VOLTAGE CMOS
OCTAL TRANSCEIVER/
REGISTERED TRANSCEIVER
DT SUFFIX
24−LEAD PLASTIC TSSOP PACKAGE
CASE 948H
DW SUFFIX
24−LEAD PLASTIC SOIC PACKAGE
CASE 751E
PIN NAMES
Pins
Function
A0−A7
B0−B7
CAB, CBA
SAB, SBA
DIR, OE
Side A Inputs/Outputs
Side B Inputs/Outputs
Clock Pulse Inputs
Select Control Inputs
Output Enable Inputs
© Semiconductor Components Industries, LLC, 2006
1
June, 2006 − Rev. 5
Publication Order Number:
MC74LCX646/D