FST3125 4-Bit Bus Switch
August 1997
Revised January 2001
FST3125
4-Bit Bus Switch
General Description
The Fairchild Switch FST3125 provides four high-speed
CMOS TTL-compatible bus switches. The low on resis-
tance of the switch allows inputs to be connected to out-
puts without adding propagation delay or generating
additional ground bounce noise.
The device is organized as four 1-bit switches with sepa-
rate OE inputs. When OE is LOW, the switch is ON and
Port A is connected to Port B. When OE is HIGH, the
switch is OPEN and a high-impedance state exists
between the two ports.
Features
s
4
鈩?/div>
switch connection between two ports.
s
Minimal propagation delay through the switch.
s
Low l
CC
.
s
Zero bounce in flow-through mode.
s
Control inputs compatible with TTL level.
Ordering Code:
Order Number
FST3125M
FST3125QSC
FST3125MTC
Package Number
M14A
MQA16
MTC14
Package Description
14-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
16-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150 Wide
14-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter 鈥淴鈥?to the ordering code.
Logic Diagram
Connection Diagrams
Pin Assignment for SOIC and TSSOP
Pin Assignment for QSOP
Pin Descriptions
Pin Name
OE
1
, OE
2
, OE
3
, OE
4
1A, 2A, 3A, 4A
1B, 2B, 3B, 4B
NC
Description
Bus Switch Enables
Bus A
Bus B
Not Connected
Inputs
OE
L
H
漏 2001 Fairchild Semiconductor Corporation
DS500043
Inputs/Outputs
A,B
A
=
B
Z
www.fairchildsemi.com
Truth Table
1
2
3
4
5
