10.3

3

IDT54/74FST3257

QUAD 2:1 MUX/DEMUX BUS SWITCH

COMMERCIAL TEMPERATURE RANGES

POWER SUPPLY CHARACTERISTICS

SWITCHING CHARACTERISTICS OVER OPERATING RANGE

Following Conditions Apply Unless Otherwise Specified:

NOTES:

1. For conditions shown as Max. or Min., use appropriate value specified under Electrical Characteristics for the applicable device type.

°C ambient.

4. This parameter is not directly testable, but is derived for use in Total Power Supply Calculations.

All currents are in milliamps and all frequencies are in megahertz.

Symbol

Parameter

Min.

Max.

Unit

Quiescent Power Supply Current

TTL Inputs HIGH

—

0.5

1.5

mA

Dynamic Power Supply

Outputs Open

—30

40

µA/

MHz/

Enable Pin Toggling

50% Duty Cycle

Switch

Outputs Open

Enable Pin Toggling

—

1.2

1.6

mA

(4 Switches Toggling)

fi = 10MHz

50% Duty Cycle

—

1.5

2.4

3257 tbl 06

Symbol

Description

Typ.

Max.

Unit

Data Propagation Delay

Ω

—

—

0.25

ns

Switch Multiplex Delay

S to I, Z

1.5

—

5.2

ns

Switch Turn on Delay

E to I, Z

1.5

—

4.8

ns

Switch Turn off Delay

1.5

—

5.0

ns

—

1.5

—

pC

—

0.5

—

pC

NOTES:

1. See test circuit and waveforms.

2.

Minimum limits guaranteed but not tested.

3. This parameter is guaranteed by design but not tested.

4. The bus switch contributes no propagation delay other than the RC delay of the on resistance of the switch and the load capacitance. The time constant

for the switch alone is of the order of 0.25 ns for 50 pF load. Since this time is constant and much smaller than the rise/fall times of typical driving signals,

it adds very little propagation delay to the system. Propagation delay of the bus switch when used in a system is determined by the driving circuit on the

driving side of the switch and its interaction with the load on the driven side.

5. Measured at switch turn off, load = 50 pF in parallel with 10 m

7. Characterized parameter. Not 100% tested.

3257 tbl 07