December 1990 2
Philips Semiconductors Product specification
Octal D-type transparent latch; 3-state 74HC/HCT573
FEATURES
• Inputs and outputs on opposite 
sides of package allowing easy 
interface with microprocessors
• Useful as input or output port for 
microprocessors/microcomputers
• 3-state non-inverting outputs for 
bus oriented applications
• Common 3-state output enable 
input
• Functionally identical to the “563” 
and “373”
• Output capability: bus driver
• ICC category: MSI
GENERAL DESCRIPTION
The 74HC/HCT573 are high-speed 
Si-gate CMOS devices and are pin 
compatible with low power Schottky 
TTL (LSTTL). They are specified in 
compliance with JEDEC standard no. 
7A.
The 74HC/HCT573 are octal D-type 
transparent latches featuring 
separate D-type inputs for each latch 
and 3-state outputs for bus oriented 
applications. 
A latch enable (LE) input and an 
output enable (OE) input are common 
to all latches.
The “573” consists of eight D-type 
transparent latches with 3-state true 
outputs. When LE is HIGH, data at
the D
n
 inputs enter the latches. In this 
condition the latches are transparent, 
i.e. a latch output will change state 
each time its corresponding D-input 
changes.
When LE is LOW the latches store the 
information that was present at the 
D-inputs a set-up time preceding the 
HIGH-to-LOW transition of LE. 
When OE is LOW, the contents of the 
8 latches are available at the outputs. 
When OE is HIGH, the outputs go to 
the high impedance OFF-state. 
Operation of the OE input does not 
affect the state of the latches.
The “573” is functionally identical to 
the “563” and “373”, but the “563” has 
inverted outputs and the “373” has a 
different pin arrangement.
QUICK REFERENCE DATA
GND = 0 V; T
amb
=25°C; tr=tf= 6 ns
Notes
1. C
PD
 is used to determine the dynamic power dissipation (PD in µW):
PD=CPD× V
CC
2
× fi+∑ (CL× V
CC
2
 × fo) where: 
fi= input frequency in MHz; fo= output frequency in MHz 
∑ (CL× V
CC
2
× fo) = sum of outputs
CL= output load capacitance in pF; VCC= supply voltage in V
2. For HC the condition is VI= GND to VCC; for HCT the condition is VI= GND to VCC− 1.5 V
ORDERING INFORMATION
See
“74HC/HCT/HCU/HCMOS Logic Package Information”
.
SYMBOL PARAMETER CONDITIONS
TYPICAL
UNIT
HC HCT
t
PHL/ tPLH
propagation delay CL= 15 pF; VCC=5 V
D
n
 to Q
n
14 17 ns
LE to Q
n
15 15 ns
C
I
input capacitance 3.5 3.5 pF
C
PD
power dissipation capacitance per latch notes 1 and 2 26 26 pF