FSTU6800 10-Bit Bus Switch with Pre-Charged Outputs
December 1998
Revised December 1999
FSTU6800
10-Bit Bus Switch with Pre-Charged Outputs
and
鈭?V
Undershoot Hardened Circuit (UHC錚? Protection
General Description
The Fairchild Switch FSTU6800 provides 10-bits of high-
speed CMOS TTL-compatible bus switching. The low on
resistance of the switch allows inputs to be connected to
outputs without adding propagation delay or generating
additional ground bounce noise. Both the A Ports and the B
Ports are 鈥渦ndershoot hardened鈥?with UHC錚?protection to
support an extended input range to 2.0V below ground.
Fairchild鈥檚 integrated Undershoot Hardened Circuit, UHC
senses undershoot at the I/Os, and responds by preventing
voltage differentials from developing and turning on the
switch. The device also precharges the B Port to a select-
able bias voltage (BiasV) to minimize live insertion noise.
The device is organized as a 10-bit switch with a bus
enable (OE) signal. 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 the B Port is precharged to BiasV
through an equivalent 10-k鈩?resistor.
Features
s
4鈩?switch connection between two ports.
s
Undershoot Hardened to -2.0V.
s
Soft enable turn-on to minimize bus-to-bus charge
sharing during enable.
s
Low l
CC
.
s
Zero bounce in flow-through mode.
s
Output precharge to minimize live insertion noise.
s
Control inputs compatible with TTL level.
s
See Applications Note AN-5008 for details.
Ordering Code:
Order Number
FSTU6800WM
FSTU6800QSC
FSTU6800MTC
Package Number
M24B
MQA24
MTC24
Package Description
24-Lead Small Outline Integrated Circuit (SOIC), JEDEC MO-153 4.4mm Wide
24-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150鈥?Wide
24-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 Diagram
Pin Descriptions
Pin Name
OE
A
B
BiasV
Description
Bus Switch Enable
Bus A
Bus B
Bus B Voltage Bias
OE
L
H
B
0
鈥揃
9
A
0
鈥揂
9
BiasV
Function
Connect
Precharge
Truth Table
UHC錚?is a trademark of Fairchild Semiconductor Corporation.
漏 1999 Fairchild Semiconductor Corporation
DS500194
www.fairchildsemi.com
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