FST32xxx 鈥?28鈩?/div>
鈥?TTL-compatible input and output levels
鈥?ESD > 2000V per MIL-STD-883, Method 3015;
> 200V using machine model (C = 200pF, R = 0)
鈥?Available in QSOP, TSSOP, SOIC and PDIP
鈥?Pin-compatible with FCT245/FCT245T
DESCRIPTION:
The FST3245/32245 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 or the
resistance 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 FST32245 integrates terminating resistors in the de-
vice, thus eliminating the need for external 25鈩?series resis-
tors.
The FST3245 and FST32245 are octal TTL-compatible
bus switches. The
OE
pin provides output enable control for
all 8 bits. The direction control pin (DIR) of the FCT245/
FCT245T is replaced with a "No connect" (NC) in the FST3245/
32245. Bus switch devices provide an inherently bidirectional
connection between ports, thus eliminating the purpose of the
direction control pin.
FUNCTIONAL BLOCK DIAGRAM
A
0
A
1
A
2
A
3
A
4
A
5
A
6
A
7
OE
3256 drw 01
PIN CONFIGURATION
NC
A
0
A
1
A
2
A
3
A
4
A
5
A
6
A
7
GND
1
2
3
4
5
6
7
8
9
10
P20-1
SO20-2
SO20-8
SO20-9
20
19
18
17
16
15
14
13
12
11
Vcc
OE
B
0
B
1
B
2
B
3
B
4
B
5
B
6
B
7
B
0
B
1
B
2
B
3
B
4
B
5
B
6
B
7
PIN DESCRIPTION
Pin Names
OE
NC
A
0-
A
7
B
0-
B
7
Description
Output Enable Input (Active LOW)
No connect
A Port Bits
B Port Bits
3256 tbl 01
DIP/SOIC/
QSOP/TSSOP
TOP VIEW
3256 drw 02
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
COMMERCIAL TEMPERATURE RANGES
漏1996
Integrated Device Technology, Inc.
AUGUST 1996
10.2
DSC-3256/2
1
1
2
3
4
5
