Philips Semiconductors

Product specification

74ALS573B/74ALS574A

Latch/flip-flop

74ALS573B

Octal transparent latch (3-State)

74ALS574A

Octal D flip-flop (3-State)

2

1991 Feb 08

853–1307 01670

FEATURES

interface to microprocessors

and 74ALS574A respectively

DESCRIPTION

The 74ALS573B is an octal transparent latch coupled to eight

3-State output devices. The two sections of the device are controlled

independently by enable (E) and output enable (OE) control gates.

The 74ALS573B is functionally identical to the 74ALS373 but has a

broadside pinout configuration to facilitate PC board layout and

allow easy interface with microprocessors.

The data on the D inputs is transferred to the latch outputs when the

enable (E) input is High. The latch remains transparent to the data

input while E is High, and stores the data that is present one setup

time before the High-to-Low enable transition.

The 74ALS574A is functionally identical to the 74ALS374 but has a

broadside pinout configuration to facilitate PC board layout and

allow easy interface with microprocessors.

It is an 8-bit edge triggered register coupled to eight 3-State output

buffers. The two sections of the device are controlled independently

by clock (CP) and output enable (OE) control gates.

The register is fully edge triggered. The state of the D input, one

setup time before the Low-to-High clock transition is transferred to

the corresponding flip-flop’s Q output.

The active-Low output enable (OE) controls all eight 3-State buffers

independent of the latch operation. When OE is Low, latched or

transparent data appears at the output.

When OE is High, the outputs are in high impedance “off” state,

which means they will neither drive nor load the bus.

TYPE

TYPICAL

PROPAGATION

DELAY

TYPICAL

SUPPLY CURRENT

(TOTAL)

74ALS573B

5.0ns

12mA

74ALS574A

6.0ns

15mA

ORDERING INFORMATION

ORDER CODE

DESCRIPTION

COMMERCIAL RANGE

DRAWING

NUMBER

20-pin plastic DIP

74ALS573BN, 74ALS574AN

SOT146-1

20-pin plastic SOL

74ALS573BD, 74ALS574AD

SOT163-1

20-pin plastic SSOP

Type II

74ALS573BDB,

74ALS574ADB

SOT339-1

INPUT AND OUTPUT LOADING AND FAN-OUT TABLE

PINS

DESCRIPTION

74ALS (U.L.)

HIGH/LOW

LOAD VALUE

HIGH/LOW

D0 – D7

Data inputs

1.0/1.0

20

µA/0.2mA

E (74ALS573B)

Latch enable input

1.0/1.0

20

µA/0.1mA

OE

Output Enable input (active-Low)

1.0/1.0

20

µA/0.1mA

CP (74ALS574A)

Clock pulse input (active rising edge)

1.0/2.0

20

µA/0.2mA

Q0 – Q7

Data outputs

130/240

2.6mA/24mA

NOTE:

One (1.0) ALS unit load is defined as: 20

µA in the High state and 0.1mA in the Low state.