2001-04-12 Page
1
MDSS-0009-01
www.vaishali.com
Vaishali Semiconductor 747 Camden Avenue, Suite C Campbell CA 95008 Ph. 408.377.6060 Fax 408.377.6063
Applications
=
5V to 3.3V translation in mixed-supply
environment
=
Hot-swap interface
=
Logic replacement
=
Memory bank, video, & audio
swtiching
=
Power conservation
General Description
The VS3257 is a high-speed TTLcompatible Quad 2:1 multiplexer/demultiplexer. The VS3257 contains four
mux/demux channels, with a common path control (S) and active low enable (/E). The low ON resistance of
the VS3257 allows inputs to be connected to outputs, without adding propagation delay and without
generating additional signal noise. The VS32257 has 25
resistors in series with the switches to reduce
ground-bounce noise and signal reflection.
The VS3257 and VS32257 mux/demux switches are function and pinout compatible with QS3257 and
CBT3257 switches. They enable 5V to 3.3V translation when used with an external diode in the power supply
line. In addition, the high off-isolation in the `disable' mode makes VS3257 and VS32257 ideal interface
elements for hot-swap applications.
Figure 1. Functional Block Diagram Figure 2. Pin Configuration
VS3257 / VS32257
Quad 2:1 Mux/Demux VSwitch
Features
=
Enhanced N-FET with no DC path to V
CC
or GND in normal operating signal voltage
range.
=
Low impedance bidirectional data flow:
5
(VS3257) and 25
(VS32257)
=
Pin-compatible with QS3257 and CBT3257
switches.
=
Near zero propagation delay
=
Zero added ground bounce or signal noise
=
Break-before-make feature
=
TTL-compatible control signals
=
Undershoot clamp diodes on all switch and
control pins
=
ESD rating >2000V (Human Body Model)
or >200V (Machine Model)
=
Latch-up current >100mA
=
Available in 150-mil wide QSOP package
I0
A
I1
A
I0
B
I1
B
S
/E
Y
A
Y
B
Y
C
Y
D
I0
C
I1
C
I0
D
I1
D
(All Pins Top View)
GND
V
CC
I0
D
I1
D
Y
D
I0
C
I1
C
Y
C
/E
QSOP
S
I0
A
I1
A
Y
A
I0
B
I1
B
Y
B
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VS3257/VS32257
2001-04-12 Page
2
MDSS-0009-01
www.vaishali.com
Vaishali Semiconductor 747 Camden Avenue, Suite C Campbell CA 95008 Ph. 408.377.6060 Fax 408.377.6063
Table 1. Pin Description
Name I/O Description
I0
X
, I1
X
I/O
Data Input or Output
S I
Select
Input
/E I Enable
Input
Y
A
- Y
D
I/O
Data Output or Input
Table 2. Function Table
Inputs Path Function
/E S
H
X
Hi Impedance
Disable all switches
L L IO
X
<-> Y
X
Select
0
L H I1
X
<-> Y
X
Select
1
Table 3. Absolute Maximum Ratings
Supply Voltage to Ground....................................-0.5V to +7.0V
DC Switch Voltage V
S
.........................................-0.5V to +7.0V
DC Input Voltage V
IN
....................................... ...-0.5V to +7.0V
AC Input Voltage (Pulse Width < 20ns)...............................-3.0V
DC Output Sink Current per Switch Pin.............................120 mA
Maximum Power Dissipation.......................................0.5 Watts
Storage Temperature.......................................-65
o
C to +150
o
C
Note
ABSOLUTE MAXIMUM CONTINUOUS RATINGS are those values beyond which damage to the device may
occur. Exposure to these conditions or conditions beyond those indicated may adversely affect device reliability.
Correct functional operation while operating in the absolute maximum rated conditions is not implied.
Table 4. Capacitance
T
A
= 25
o
C, f = 1 MHz, V
IN
= 0V, V
OUT
= 0V
QSOP
Pins Operation
Typ
Max
Unit
Control Inputs
4
5
pF
VSwitch Channels
Demux
5
7
pF
(Switch OFF)
Mux
7
8
pF
Note
Capacitance is guaranteed, but not production tested. Total capacitance of a path, when the switch is closed, is
the sum of the switch terminal capacitances.
VS3257/VS32257
2001-04-12 Page
3
MDSS-0009-01
www.vaishali.com
Vaishali Semiconductor 747 Camden Avenue, Suite C Campbell CA 95008 Ph. 408.377.6060 Fax 408.377.6063
Table 5. Recommended Operating Conditions
Symbol Parameter Conditions
Min
Typ
Max
Units
V
CC
Power supply voltage
4.5
5.5
V
V
IL
Low level input voltage
-0.5
0.8
V
V
IH
High level input voltage
2.0
5.5
V
T
A
Operating free-air temperature
-40
85
o
C
Note:
1. All unused control inputs of the device must be held at Vcc or GND, to ensure proper device operation
Table 6. Electrical Characteristics Over Recommended Operating Free-air Temperature Range
Symbol Parameter
Test
Conditions
Min
Typ
(1)
Max Units
Control Inputs
-1.5
V
IK
Clamp
Voltage
Switch I/O
V
CC
= Min, I
IK
= -18 mA
-1.5
V
V
IN
= V
CC
= 5V, I
OUT
= -5
A
3.7 3.9 4.1
V
OH
Logic High Voltage
Switch I/O
V
CC
= 4.3V, V
N
= 5V,
I
OUT
= -5
A
3.0 3.3 3.6
V
I
I
Input Leakage
Current
Control Inputs
V
CC
= Max, V
I
= V
CC
or GND
1
A
Control Inputs
|
OFF
|
Power OFF Leakage
Current
Switch I/O
V
CC
= 0,
V
I
or V
O
= V
CC
or GND
1
A
|I
OZ
|
OFF State Leakage
Current
Switch I/O
V
CC
= Max, V
I/O
= V
CC
,
/E = V
CC
1
A
VS3257 50
mA
I
ODL
Switch I/O Drive
Current (Logic LOW)
V
CC
= Min, V
IN
= 0,
V
OUT
= 0.4V
VS32257
mA
VS3257 -50
mA
I
ODH
Switch I/O Drive
Current (Logic HIGH)
V
CC
= Min, V
IN
= V
CC
,
V
OUT
= 2.4V
VS32257
mA
VS3257
5
7
R
ON
Switch
ON
Resistance
(2)
V
CC
= Min, V
IN
= 0,
I
OUT
= 30mA
VS32257 20 28 40
Notes:
1. Typical values are specified at V
CC
= 5.0V and T
A
= 25
o
C.
2. R
ON
is measured by forcing specified current into the `output' node of the switch with the `input' node of the switch at the the
specified voltage
Table 7. Power Supply Characteristics Over Recommended Operating Free-air Temperature Range
Symbol Parameter
Test
Conditions
(1)
Max
Units
I
CCQ
Quiescent Power Supply Current
V
CC
= Max, S, /E = V
CC
or GND, f = 0
1
A
I
CC
Power Supply Current per Input High
(Control Inputs)
(2)
V
CC
= Max, V
IN
= 3.4V, f = 0
1.5
mA
Q
CCD
Dynamic Power Supply Current
(3)
V
CC
= Max, Switch pins open,
Control Inputs toggling at 50% duty cycle
0.25 mA/MHz
Notes:
1. For conditions shown as Min or Max, use the appropriate values per Recommended Operating Conditions.
2. Per TTL-driven control input. All other control inputs at GND. Switch I/O pins do not contribute to
ICC.
3. This parameter represents the average DC current resulting from the switching of internal nodes of the device at a given
frequency. The switch I/O pins make insignificant contribution to the dynamic power supply current of the device. This parameter
is guaranteed, but not production tested.
VS3257/VS32257
2001-04-12 Page
4
MDSS-0009-01
www.vaishali.com
Vaishali Semiconductor 747 Camden Avenue, Suite C Campbell CA 95008 Ph. 408.377.6060 Fax 408.377.6063
3
4
5
Vout
(V)
0
1
2
Vin (V)
4 5
3
2
1
0
VCC = 4.3V
Figure 4. VOH CHARACTERISTICS
VOH
Output Voltage
(V)
2.0
2.5
VCC Supply Voltage (V)
5.5
5.0
4.5
3.5
3.0
4.0
4.5
4.75 5.25
TA = 85
C
TA = 25
C
TA = - 40
C
Figure 3. VOLTAGE TRANSLATION
Figure 5. Voltage Translation. Application
V
CC
10K
V
CC
= 5V
/E
I/O
VS3257
VS32257
3.3V
DEVICE
5V
DEVICE
I/O
1N4148
or equivalent
VS3257/VS32257
2001-04-12 Page
5
MDSS-0009-01
www.vaishali.com
Vaishali Semiconductor 747 Camden Avenue, Suite C Campbell CA 95008 Ph. 408.377.6060 Fax 408.377.6063
Table 8. Switching Characteristics Over Operating Range
T
A
= -40
o
C to +85
o
C, V
CC
= 5.0V + 10
%
C
LOAD
= 50pF, R
LOAD
= 500
unless otherwise stated.
Symbol
Description
(1)
VS3257
Min
(3)
Max
VS32257
Min
(3)
Max
Units
t
PLH
, t
PHL
Data Propagation Delay
(2,3)
through the switch
0.25
1.25
ns
t
PZH
, t
PZL
Switch Turn-on Delay, S to Y
X
, I0
X
, or I1
X
0.5
5.2
0.5
6.2
ns
t
PZH
, t
PZL
Switch Turn-on Delay, /E to Y
X
, I0
X
, or I1
X
0.5
4.8
0.5
5.8
ns
t
PLZ
, t
PHZ
Switch Turn-off Delay
(3)
,
S or /E to Y
X
, I0
X
, or I1
X
0.5
5.0
0.5
5.0
ns
Notes:
1. See test circuits and waveforms.
2. This parameter is the calculated theoretical RC time constant of ON-state resistance of the switch and the specified load
capacitance when driven by an ideal voltage source (zero source impedance). This time-constant is on the order of 0.25 ns for
VS3257 and 1.25 ns for VS32257. Since this time-constant is much smaller than rise/fall times of typical driving signals, it adds
very little propagation delay to the system.
3. This parameter is guaranteed, but not production tested.
Figure 6. AC Test Circuit and Switching Waveforms
AC Test Circuit
Load Switch
Position
TEST S1
t
PLH
, t
PHL
Open
t
PLZ
, t
PZL
Closed
t
PHZ
, t
PZH
Open
Input Conditions
Input voltage = 0 V to 3.0 V
t
r
= t
f
= 2.5ns (10% to 90%)
Pulse
Generator
DUT
V
IN
V
OUT
C
L
500
R
L
S
1
7 V
50
=
Coax to
Oscilloscope
50
450
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