1
PS8150D 05/15/01
PI3B3251
3.3V, 8:1 Mux/Demux BusSwitch
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Product Features
Near zero propagation delay
5 Ohm switches connect inputs to outputs
Ultra Low Quiescent Power (0.1A Typical)
Ideally suited for notebook applications
Pin compatible with 74 series 251 logic devices
Packages available:
16-pin 150 mil wide plastic QSOP (Q)
16-pin 150 mil wide plastic SOIC (W)
16-pin 173 mil wide plastic TSSOP (L)
Select
E
S
2
S
1
S
0
Y
Function
H
X
X
X
Hi-Z
Disable
L
L
L
L
I0
S2-0 = 0
L
L
L
H
I1
S2-0 = 1
L
L
H
L
I2
S2-0 = 2
L
L
H
H
I3
S2-0 = 3
L
H
L
L
I4
S2-0 = 4
L
H
L
H
I5
S2-0 = 5
L
H
H
L
I6
S2-0 = 6
L
H
H
H
I7
S2-0 = 7
Truth Table
(1)
Logic Block Diagram
Product Description
Pericom Semiconductor's PI3B series of logic circuits are produced
using the Company's advanced sub micron CMOS technology,
achieving industry leading performance.
The PI3B3251 is a 3.3V Dual 8:1 Multiplexer/demultiplexer with three-
state outputs that is pinout compatible with the PI74FCT251T,
74F251, and 74ALS/AS/LS 251. Inputs can be connected to outputs
with low on resistance (5 Ohm) with no additional ground bounce
noise or propagation delay.
Product Pin Configuration
Product Pin Description
Pin Name
Description
I
0
7
Data Inputs
S
0
2
Select Inputs
E
Enable
Y
Data Outputs
GND
Ground
V
CC
Power
Note:
1. H = High Voltage Level
L = Low Voltage Level
V
CC
I
3
1
I
4
I
2
2
I
5
I
1
3
I
6
I
0
4
I
7
Y
5
16
S
0
NC
6
15
S
1
E
7
14
S
2
8
13
12
GND
11
10
9
16-Pin
Q, W, L
I0
E
S0
S1
S2
I1
I2
I3
I4
I5
I6
I7
Y
PI3B3251
3.3V, 8:1 Mux/Demux BusSwitch
2
PS8150D 05/15/01
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Capacitance
(T
A
= 25C, f = 1 MHz)
Parameters
(5)
Description
Test Conditions
Typ.
Units
C
IN
Input Capacitance
V
IN
= 0V
3.0
pF
C
I
(
OFF
)
I
0
- I
7
Capacitance, Switch Off
V
IN
= 0V
8.0
pF
C
Y
(OFF)
Y Capacitance, Switch Off
V
IN
= 0V
64.0
pF
C
I
(ON)
I
0
- I
7
Capacitance, Switch On
V
IN
= 0V
72.0
pF
Notes:
1. For Max. or Min. conditions, use appropriate value specified under Electrical Characteristics for the applicable device type.
2. Typical values are at V
cc
= 3.3V, T
A
= 25C ambient and maximum loading.
3. Measured by the voltage drop between I and Y pin at indicated current through the switch. ON resistance is determined by the
lower of the voltages on the two (I,Y) pins.
4. This parameter is determined by device characterization but is not production tested.
Storage Temperature ................................................................... 65C to +150C
Ambient Temperature with Power Applied ..................................... 40C to +85C
Supply Voltage to Ground Potential (Inputs & V
CC
Only) ............... 0.5V to +4.6V
Supply Voltage to Ground Potential (Outputs & D/O Only ............. 0.5V to +4.6V
DC Input Voltage .............................................................................. 0.5V to +4.6V
DC Output Current ....................................................................................... 120mA
Power Dissipation ............................................................................................ 0.5W
Note:
Stresses greater than those listed under MAXIMUM RATINGS may cause permanent
damage to the device. This is a stress rating only and functional operation of the device
at these or any other conditions above those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect reliability.
Maximum Ratings
(Above which the useful life may be impaired. For user guidelines, not tested.)
DC Electrical Characteristics
(Over the Operating Range, T
A
= 40C to +85C, V
CC
=3.3V 10%)
Parameters Description
Test Conditions
(1)
Min.
Typ
(2)
Max.
Units
V
IH
Input HIGH Voltage
Guaranteed Logic HIGH Level
2.0
V
V
IL
Input LOW Voltage
Guaranteed Logic LOW Level
0.5
0.8
V
I
IH
Input HIGH Current
V
CC
= Max., V
IN
= V
CC
1
A
I
IL
Input LOW Current
V
CC
= Max., V
IN
= GND
1
A
I
OZH
High Impedance Output Current 0
I
N
, Y
N
V
CC
1
A
V
IK
Clamp Diode Voltage
V
CC
= Min., I
IN
= 18mA
1.2
V
R
ON
Switch On Resistance
(3)
V
CC
= Min., V
IN
= 0.0V, I
ON
= 48mA or 64mA
5
8
V
CC
= Min., V
IN
= 2.4V, I
ON
= 15mA
10
17
PI3B3251
3.3V, 8:1 Mux/Demux BusSwitch
3
PS8150D 05/15/01
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PI3B3251
Com.
Parameters Description
Conditions
(1)
Min.
Max.
Units
t
PD
Propagation Delay
(2,3)
C
L
= 50pF
0.25
In to Y
R
L
= 500
t
SY
Bus Enable Time
C
L
= 50pF R
L
= 500
1
4.5
Sn to Y
t
PZH
Bus Enable Time
C
L
= 50pF R
L
= 500
1
3.5
t
PZL
E to Y
t
PHZ
Bus Disable Time
C
L
= 50pF R
L
= 500
1
5.5
t
PLZ
E to Y
Power Supply Characteristics
Parameters Description
Test Conditions
(1)
Min.
Typ.
(2)
Max.
Units
I
CC
Quiescent Power
V
CC
= Max.
V
IN
= GND or V
CC
0.1
3
A
Supply Current
I
CC
Supply Current per
V
CC
= Max.
V
IN
= 3.0V
(3)
750
A
Input @ TTL HIGH
Notes:
1. For Max. or Min. conditions, use appropriate value specified under Electrical Characteristics for the applicable device.
2. Typical values are at V
CC
= 3.3V, +25C ambient.
3. Per TTL driven input (control input only); I and Y pins do not contribute to I
CC
.
Switching Characteristics over Operating Range
Notes:
1. See test circuit and waveforms.
2. This parameter is guaranteed but not tested on Propagation Delays.
3. The bus switch contributes no propagational delay other than the RC delay of the ON resistance
of the switch and the load capacitance. The time constant for the switch alone is of the order of 0.25ns
for 50pF load. Since this time constant is much smaller than the rise/fall times of typical driving
signals, it adds very little propagational delay to the system. Propagational delay of the bus switch
when used in a system is determined by the driving circuit on the driving side of the switch and its
interaction with the load on the driven side.
Pericom Semiconductor Corporation
2380 Bering Drive San Jose, CA 95131 1-800-435-2336 Fax (408) 435-1100 http://www.pericom.com
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Ordering Information
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