Fairchild FSTU3257 service manual
August 1999
Revised October 2006
FSTU3257
Quad 2:1 Multiplexer/Demultiplexer Bus Switch with
2V Undershoot Protection
FSTU3257 Quad 2:1 Multiplexer/Demultiplexer Bus Switch with 2V Undershoot Protection
General Description
The Fairchild Swit ch FSTU3257 is a quad 2:1 h igh-speed
CMOS TTL-compatible multiplexer/demultiplexer bus
switch. The low on resistance of the switch allows inputs to
be connected to outputs wit hout adding pro pagation delay
or generating additional ground bounce noise.
When OE
selected B Port output. The A and B Ports are “un der sho ot
hardened” with Unders hoot Hard ened Circui t (U
tection to support an extended range of 2.0V below
ground. Fairchild’s integra ted UHC senses undershoot at
the I/O and responds by preventing voltage differentials
from developing and turning on the switch. When OE
HIGH, the switch is OPEN and a high-impedance state
exists between the two ports.
is LOW, the select pin connects the A Port to the
HC®
¥
Features
■ Undershoot hardened to
■ Soft enable turn-on to minimize bus to bus charge
sharing during enable
■ 4
:
switch connection between two ports.
■ Minimal propagation delay through the switch.
■ Low l
) pro-
■ Zero bounce in flow-through mode.
■ Control inputs compatible with TTL level.
■ See Applications Note AN-5008 for details
is
.
CC
2V (A and B Ports)
Ordering Code:
Order Number Package Number Package Description
FSTU3257M M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow
FSTU3257QSC MQA16 16-Lead Quarter Size Outline Package (QSOP), JEDEC MO-137, 0.150" Wide
FSTU3257MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
Device also available in Tape and Reel. Specify by appending suffix let te r “X” to the ordering code.
Logic Diagram
Connection Diagram
Pin Descriptions
Pin Name Description
OE
S Select Input
ABus A
B
1–B2
UHC®¥ is a registered trademark of Fairchild Semiconductor Corporation.
© 2005 Fairchild Semiconductor Corporation DS500302 www.fairchildsemi.com
Bus Switch Enable
Bus B
Truth Table
SOE Function
X H Disconnect
LL A
HL A
B
1
B
2
Absolute Maximum Ratings(Note 1) Recommended Operating
Supply Voltage (VCC)
DC Switch Voltage (V
FSTU3257
DC Input Control Pin Voltage (V
S
DC Input Diode Current (l
DC Output (I
DC V
CC
) 128mA
OUT
/GND Current (ICC/I
Storage Temperature Range (T
) (Note 2)
) VIN 0V
IK
GND
)(Note 3)0.5V to 7.0V
IN
)
)
STG
65q
ESD
Human Body Model 5kV
0.5V to 7.0V
2.0V to 7.0V
50mA
/
100mA
C to 150 qC
Conditions
Power Supply Operating (V
Input Voltage (V
Output Voltage (V
Input Rise and Fall Time (t
Switch Control Input 0nS/V to 5nS/V
Switch I/O 0nS/V to DC
Free Air Operating Temperature (T
Note 1: The Absolute Maximum Ratings are those values beyond which
the safety of the d evice cannot be guaranteed. The device sh ould not be
operated at these limi ts. The parametric values define d in the Electrical
Characteristics tables are not gu arante ed at the abs olute max imum rat ing.
The Recommend ed Oper ating Cond itions tab les will def ine the co nditions
for actual device operation.
is the voltage obser v ed/applied at either th e A or B Ports across
Note 2: V
S
the switch.
Note 3: The input and output negative voltage ratings may be exceeded if
the input and output diode current ratings are observed.
Note 4: Unused control inputs must be held HIGH or LOW. They may not
float.
(Note 4)
) 4.0V to 5.5V
CC
)0V to 5.5V
IN
)0V to 5.5V
OUT
, tf)
r
)40 qC to 85 qC
A
DC Electrical Characteristics
V
Symbol Parameter
V
IK
V
IH
V
IL
I
I
I
OZ
R
ON
I
CC
'
I
CC
V
IKU
Note 5: Typi c al values are at VCC 5.0V and TA 25qC
Note 6: Measured by the voltage drop between A and B pins at t he indicated current th rough the switch. On re s is tan c e is determined by the lower of the
voltages on the two (A or B) pins.
Clamp Diode Voltage 4.5
HIGH Level Input Voltage 4.0–5.5 2.0 V
LOW Level Input Voltage 4.0–5.5 0.8 V
Input Leakage Current 5.5
OFF-STATE Leakage Current 5.5
Switch On Resistance 4.5 4 7
(Note 6) 4.5 4 7
Quiescent Supply Current 5.5 3
Increase in I
Voltage Undershoot 5.5
per Input 5.5 2.5 mA One input at 3.4V
CC
CC
(V)
4.5 8 15
4.0 11 20
TA 40 qC to 85 qC
Min Typ
(Note 5)
Units Conditions
Max
1.2 V IIN 18mA
r
1.0
P
r
1.0
2.0 V 0.0 mA t IIN t 50 mA
A0d VIN d5.5V
P
A0 dA, B dV
:
:
:
:
P
AVIN VCC or GND, I
CC
VIN 0V, IIN 64mA
VIN 0V, IIN 30mA
V
2.4V, IIN 15mA
IN
2.4V, IIN 15mA
V
IN
Other inputs at V
OE
5.5V
CC
0
OUT
or GND
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