http://onsemi.com
10
Section 1 – Descriptions and Family Characteristics
FACT – Logic
ON Semiconductor FACT logic offers a unique
combination of high speed, low power dissipation, high
noise immunity, wide fan-out capability, extended power
supply range and high reliability.
This data book describes the product line with device
specifications as well as material discussing design
considerations and comparing the FACT family to
predecessor technologies.
The sub two-micron silicon gate CMOS process utilized
in this family has been proven in the field. It has been further
enhanced to meet and exceed the JEDEC standards for
74ACXX logic.
For direct replacement of LS, ALS and other TTL devices,
the ‘ACT circuits with TTL-type input thresholds are
included in the FACT family. These include the more
popular bus drivers/transceivers as well as many other
74ACTXXX devices.
Characteristics
Full Logic Product Line
Industry Standard Functions and Pinouts for SSI, MSI
and LSI
Meets or Exceeds JEDEC Standards for 74ACXX
Family
TTL Inputs on Selected Circuits
High Performance Outputs
Common Output Structure for Standard and Buffer
Drivers
Output Sink/Source Current of 24 mA
Transmission Line Driving 50 ohm (Commercial)
Guaranteed
Operation from 2–6 Volts Guaranteed
Temperature Range –40°C to +85°C (Commercial)
Improved ESD Protection Network
High Current Latch-Up Immunity
Interfacing
FACT devices have a wide operating voltage range (VCC
= 2 to 6 Vdc) and sufficient current drive to interface with
most other logic families available today.
Device designators are as follows:
‘AC – This is a high-speed CMOS device with CMOS input
switching levels and buffered CMOS outputs that can
drive
±24 mA of IOH and IOL current. Industry standard
′AC nomenclature and pinouts are used.
‘ACT – This is a high-speed CMOS device with a TTL-to-
CMOS input buffer stage. These device inputs are
designed to interface with TTL outputs operating with a
VCC = 5 V ± 0.5 V with VOH = 2.4 V and VOL = 0.4 V.
These devices have buffered outputs that will drive
CMOS or TTL devices with no additional interface
circuitry. ‘ACT devices have the same output structures
as ‘AC devices.
Low Power CMOS Operation
If there is one single characteristic that justifies the
existence of CMOS, it is low power dissipation. In the
quiescent state, FACT draws three orders of magnitude less
power than the equivalent LS or ALS TTL device. This
enhances system reliability; because costly regulated high
current power supplies, heat sinks and fans are eliminated,
FACT logic devices are ideal for portable systems such as
laptop computers and backpack communications systems.
Operating power is also very low for FACT logic. Power
consumption of various technologies with a clock frequency
of 1 MHz is shown below.
FACT = 0.1 mW/Gate
ALS
= 1.2 mW/Gate
LS
= 2.0 mW/Gate
HC
= 0.1 mW/Gate
500
400
300
200
100
0
02
4
6
CL = 50 pF @ 1 MHz
CL = FIXTURE CAPACITANCE
@ 1 MHz
VCC (VOLTS)
I CC
(
Figure 1–1. ICC versus VCC
A)
Figure 1–1 illustrates the effects of ICC versus power
supply voltage (VCC) for two load capacitance values: 50 pF
and stray capacitance. The clock frequency was 1 MHz for
the measurements.
AC Performance
In comparison to LS, ALS and HC families, FACT
devices have faster internal gate delays. Additionally, as the
level of integration increases, FACT logic leads the way to
very high- speed systems.