4-BIT BUS SWITCH
IDT74FST3125
Integrated Device Technology, Inc.
FEATURES:
• Bus switches provide zero delay paths
• Extended commercial range of –40°C to +85°C
• Low switch on-resistance:
FST3xxx – 5Ω
• TTL-compatible input and output levels
• ESD > 2000V per MIL-STD-883, Method 3015;
> 200V using machine model (C = 200pF, R = 0)
• Available in QSOP and SOIC
DESCRIPTION:
The FST3125 belong to IDT's family of Bus switches. Bus
switch devices perform the function of connecting or isolating
two ports without providing any inherent current sink or source
capability. Thus they generate little or no noise of their own
while providing a low resistance path for an external driver.
These devices connect input and output ports through an n-
channel FET. When the gate-to-source junction of this FET is
adequately forward-biased the device conducts and the resis-
tance between input and output ports is small. Without
adequate bias on the gate-to-source junction of the FET, the
FET is turned off, therefore with no V
CC
applied, the device
has hot insertion capability.
The low on-resistance and simplicity of the connection
between input and output ports reduces the delay in this path
to close to zero.
The FST3125 is a 4-bit TTL-compatible bus switch. The
xOE pins provide individual enable control for each of the four
bits.
FUNCTIONAL BLOCK DIAGRAM
1A
1OE
1Y
PIN CONFIGURATION
1
2
3
4
5
6
7
8
SOIC/QSOP
TOP VIEW
SO16-1
SO16-7
16
15
14
13
12
11
10
9
Vcc
4OE
4A
4Y
3OE
3A
3Y
NC
NC
1OE
2A
2OE
3A
3OE
4A
4OE
2Y
1A
1Y
3Y
2OE
2A
2Y
4Y
GND
3471 drw 01
3471 drw 02
PIN DESCRIPTION
Pin Names
1A
-
4A
1Y
-
4Y
NC
1
OE
, 4
OE
I/O
I/O
I/O
—
I
Description
Bus A
Bus B
No Connect
Bus Switch Enable (Active LOW)
3471 tbl 01
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
COMMERCIAL TEMPERATURE RANGE
©1996
Integrated Device Technology, Inc.
AUGUST 1996
DSC-4668/-
1
IDT [ INTEGRATED DEVICE TECHNOLOGY ]
