1
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
INDUSTRIAL TEMPERATURE RANGE
NOVEMBER 1999
1999 Integrated Device Technology, Inc.
DSC-5533/1
c
IDTQS3ST253
INDUSTRIAL TEMPERATURE RANGE
FUNCTIONAL BLOCK DIAGRAM
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
FEATURES:
Enhanced N channel FET with no inherent diode to Vcc
Bidirectional signal flow
Flow-through pinout
Zero propagation delay, zero ground bounce
2 banks of 4:1 Mux/Demux
Port select synchronous to the clock
Undershoot clamp diodes on all switch and control inputs
Clock enable and Asynchronous enable
"Bus-hold" terminators on the Demux side
Asynchronous SEL option
Break-before-make feature
Bus-hold eliminates floating bus lines and reduces static power
consumption
Available in QSOP package
APPLICATIONS:
Video, audio, graphics switching, muxing
QUICKSWITCH
PRODUCTS
HIGH-SPEED CMOS SYNCHRO-
SWITCHTM DUAL 4:1 MUX/DEMUX
WITH ACTIVE TERMINATORS
DESCRIPTION:
The QS3ST253 is a high-speed CMOS dual 4:1 multiplexer/demultiplexer
with active terminators (bus-hold circuits) on the demux side. Port selection
and connection, controlled by SEL signals, can be either asynchronous or
synchronous. In the synchronous mode, the A, B, C, or D port to Y port
connection is updated on the rising edge of the input clock CLK. Once the
port-to-port connection is made, data flow can be bi-directional with a typical
250ps propagation delay through the switch. Clock Enable, overriding
Asynchronous Enable, and Asynchronous Select controls provide addi-
tional design flexibility.
The bus-hold circuits latch the last data driven on the demux side,
providing infinite hold time and glitch-free signal transitions. Synchronous
controls and bus-hold ease timing constraints in many high speed data mux/
demux applications, such as bank interleaving.
The QS3ST253 can be used in 5V to 3.3V translation.
Y
0
Y
1
A
0
B
0
C
0
A
1
C
1
D
0
B
1
D
1
CLKn
CLKENn
OE
0
SYNCn
OE
1
SEL
0
CONTROL
LOGIC
SEL
1
Bank 0
Bank 1
T
T
T
T
T
T
T
T
T
=
2
INDUSTRIAL TEMPERATURE RANGE
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
PIN CONFIGURATION
QSOP
TOP VIEW
Symbol
Description
Max
Unit
V
TERM
(2)
Supply Voltage to Ground
0.5 to +7
V
V
TERM
(3)
DC Switch Voltage Vs
0.5 to +7
V
V
TERM
(3)
DC Input Voltage V
IN
0.5 to +7
V
V
AC
AC Input Voltage (pulse width
20ns)
3
V
I
OUT
DC Output Current
120
mA
P
MAX
Maximum Power Dissipation (T
A
= 85C)
0.82
W
T
STG
Storage Temperature
65 to +150
C
ABSOLUTE MAXIMUM RATINGS
(1)
NOTE:
1. Stresses greater than those listed under ABSOLUTE 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.
2. Vcc terminals.
3. All terminals except Vcc.
Pins
Typ.
Max.
(1)
Unit
Control Inputs
4
5
pF
Quickswitch Channels
Demux
5
7
pF
(Switch OFF)
Mux
13
14
CAPACITANCE
(T
A
= +25C, f = 1MHz, V
IN
= 0V, V
OUT
= 0V)
NOTE:
1. This parameter is guaranteed but not production tested.
NC
A
0
A
1
B
0
B
1
GND
2
3
4
5
6
7
8
13
14
15
16
17
18
19
20
1
9
10
11
12
Vcc
CLKEN
CLK
SYNC
C
0
C
1
D
0
D
1
OE
0
SEL
1
Y
0
Y
1
SEL
0
OE
1
PIN DESCRIPTION
Pin Names
I/O
Description
A
0
- D
0
I/O
Bank 0 Demux Ports
A
1
- D
1
I/O
Bank 1 Demux Ports
Y
0
, Y
1
I/O
Mux Port
SEL
0,
SEL
1
I
Select Inputs
CLK
I
Clock
CLKEN
I
Clock Enable
OE
0,
OE
1
I
Output Enable
SYNC
I
Synchronous Enable
3
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
INDUSTRIAL TEMPERATURE RANGE
FUNCTION TABLE
(1)
NOTES:
1. H = HIGH Voltage Level
L = LOW Voltage Level
X = Don't Care
Z = High-Impedence
= LOW-to-HIGH Transition
2. Mux switches are turned off and the terminators (last value latches) hold the previous data state. The port connections can be changed by the SEL input.
3. The contents of the "Mux select register" are unchanged and the previous Mux connection is unchanged. The output (Mux port) data state will depend on the present data
state of the input (Demux port).
4. The contents of the "Mux select register" are unchanged and the last value latch holds the previous data state.
2:1
MUX
SEL
0
CLKEN
CLK
SYNC
OE
0
2:1
MUX
D
Q
To Bank 0 Switches
To Bank 1 Switches
2:1
MUX
SEL
1
2:1
MUX
D
Q
OE
1
DECODE
LOGIC
AND
SWITCH
CONTROL
CONTROL LOGIC
Control Inputs
Port Status
SYNC
OE
0
OE
1
CLK
CLKEN
SEL
0
SEL
1
Y
0
Y
1
L
L
L
L
L
L
A
0
A
1
L
L
L
L
H
L
B
0
B
1
L
L
L
L
L
H
C
0
C
1
L
L
L
L
H
H
D
0
D
1
L
H
H
L
X
X
Hold Previous Data
(2)
(Switch OFF)
Hold Previous Data
(2)
(Switch OFF)
L
L
L
H
X
X
Hold Previous Mux connection
(3)
Hold Previous Mux connection
(3)
(Switch ON)
(Switch ON)
L
H
H
H
X
X
Hold Previous Data
(4)
(Switch OFF)
Hold Previous Data
(4)
(Switch OFF)
H
L
L
X
X
L
L
A
0
A
1
H
L
L
X
X
H
L
B
0
B
1
H
L
L
X
X
L
H
C
0
C
1
H
L
L
X
X
H
H
D
0
D
1
H
H
H
X
X
X
X
Hold Previous Data
(2)
(Switch OFF)
Hold Previous Data
(2)
(Switch OFF)
4
INDUSTRIAL TEMPERATURE RANGE
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
R
ON
(ohms)
V
IN
(Volts)
TYPICAL ON RESISTANCE vs V
IN
AT V
CC
= 5V
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
2
4
6
8
10
12
14
16
Symbol
Parameter
Test Conditions
Min.
Typ.
(1)
Max.
Unit
V
IH
Input HIGH Level
Guaranteed Logic HIGH for Control Pins
2
--
--
V
V
IL
Input LOW Level
Guaranteed Logic LOW for Control Pins
--
--
0.8
V
I
IN
Input Leakage Current (Control Inputs)
0V
V
IN
V
CC
--
0.01
1
A
I
OZ
Off-State Current (Hi-Z)
0V
Y V
CC
--
--0.01
1
A
R
ON
Switch ON Resistance
(2)
V
CC
= Min., V
IN
= 0V, I
ON
= 30mA
--
7
9
V
CC
= Min., V
IN
= 2.4V, I
ON
=15mA
--
10
13
I
BHL
Input Hold Current
(3,4)
Vcc = Min.
V
IN
= 0.8V
60
--
--
A
I
BHH
(A, B, C, D)
Switch OFF
V
IN
= 2V
60
--
--
I
BH
Input Current
(5)
Vcc = Max.
V
IN
= 0V or Vcc
--
--
50
A
(A, B, C, D)
0.8 < V
IN
< 2V
--
--
500
DC ELECTRICAL CHARACTERISTICS OVER OPERATING RANGE
Following Conditions Apply Unless Otherwise Specified:
Industrial: T
A
= 40C to +85C, V
CC
= 5.0V 10%
NOTES:
1. Typical values are at V
CC
= 5.0V, T
A
= 25C.
2. Measured by voltage drop between A/B/C/D and Y pin at indicated current through the switch.
3. I
BHL
is the minimum sustaining "sink" current at the input for V
IN
= 0.8V. This parameter signifies the latching capability of the bus-hold circuit in logic LOW state.
4. I
BHH
is the minimum sustaining "source" current at the input for V
IN
= 2V. This parameter signifies the latching capability of the bus-hold circuit in logic HIGH state.
5. I
BH
is the magnitude of the input current specified under two conditions:
a) Input voltage at GND or Vcc. This indicates the input current under steady-state condition.
b) Input voltage between 0.8V and 2V (TTL input threshold range). This indicates the maximum input current during transient condition. The driver connected to the input
must overcome this current requirement in order to switch the logic state of the bus-hold circuit.
5
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
INDUSTRIAL TEMPERATURE RANGE
POWER SUPPLY CHARACTERISTICS
Symbol
Parameter
Test Conditions
(1)
Max.
Unit
I
CCQ
Quiescent Power Supply Current
V
CC
= Max., V
IN
= GND or Vcc, f = 0
3
A
I
CC
Power Supply Current per Control Input HIGH
(2)
V
CC
= Max., V
IN
= 3.4V, f = 0
1.5
mA
I
CCD
Dynamic Power Supply Current per MHz
(3)
V
CC
= Max., A/B/C/D and Y pins open
0.25
mA/MHz
Control Inputs Toggling at 50% Duty Cycle
NOTES:
1. For conditions shown as Min. or Max., use the appropriate values specified under DC Electrical Characteristics.
2. Per TLL driven input (V
IN
= 3.4V, control inputs only). A/B/C/D and Y pins do not contribute to
Icc.
3. This current applies to the control inputs only and represents the current required to switch internal capacitance at the specified frequency. The A/B/C/D and Y inputs generate
no significant AC or DC currents as they transition. This parameter is guaranteed but not production tested.
SWITCHING CHARACTERISTICS OVER OPERATING RANGE
T
A
= -40C to +85C, V
CC
= 5.0V 10%;
C
LOAD
= 50pF, R
LOAD
= 500
unless otherwise noted.
Symbol
Parameter
Min.
(1)
Typ.
Max.
Unit
t
PLH
Data Propagation Delays
(1,2)
--
0.25
--
ns
t
PHL
A/B/C/D to Y, Y to A/B/C/D
t
SEC
Clock Enable to Clock Setup Time
3
--
--
ns
t
HEC
Clock Enable to Clock Hold Time
0
--
--
ns
t
CSO
Clock to Switch Turn-On Delay
(3)
0.5
--
7
ns
t
ASO
Asynchronous Select to Switch Turn-On Delay
(3)
0.5
--
7
ns
t
W
Clock Pulse Width HIGH
3
--
--
ns
t
SCS
SEL to Clock Setup Time
3
--
--
ns
t
HCS
SEL to Clock Hold Time
0
--
--
ns
t
PZL
Asynchronous Enable to Switch Turn-On Delay
(3)
1.5
--
5.2
ns
t
PZH
t
PLZ
Asynchronous Enable to Switch Turn-Off Delay
(1,3)
1.5
--
4.8
ns
t
PHZ
NOTES:
1. This parameter is guaranteed but not tested.
2. The bus switch contributes no propagation delay other than the RC delay of the ON resistance of the switch and the load capacitance. The time constraint for the switch
alone is of the order of 0.25ns for C
L
= 50pF. Since this time constant is much smaller than the rise and fall times of typical driving signals, it adds very little propagation
delay to the system. Propagation 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.
3. Minimums guaranteed but not tested.
6
INDUSTRIAL TEMPERATURE RANGE
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
TIMING WAVEFORMS - SYNCHRONOUS MODE, DEMUX FUNCTION
SYNC
CLKEN
CLK
SEL
0
, SEL
1
Port Y
Port A
Port D
HOLD PREVIOUS DATA, DATA 1
HOLD PREVIOUS DATA, DATA 2
DATA 1
DATA 2
INVALID DATA
DATA
1
DATA 0
INVALID DATA
t
SEC
t
HEC
t
SCS
t
HCS
t
SCS
t
HCS
t
PLH,
t
PHL
t
CSO
t
PLH,
t
PHL
t
CSO
OE
0
, OE
1
DATA 1
DATA 2
DATA 0
Example: Port A to Port D / Port Y
7
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
INDUSTRIAL TEMPERATURE RANGE
TIMING WAVEFORMS - SYNCHRONOUS MODE, MUX FUNCTION
SYNC
CLKEN
CLK
SEL0
Port A
Port B
Port Y
DATA1
DATA2
INVALID DATA
DATA3
DATA4
t
SEC
t
HEC
t
SCS
t
HCS
t
SCS
t
HCS
DATA1
DATA2
DATA3
DATA4
t
CSO
t
PLH,
t
PHL
t
CSO
t
PLH,
t
PHL
Example: Port A / Port D to Port Y
8
INDUSTRIAL TEMPERATURE RANGE
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
TIMING WAVEFORMS - ASYNCHRONOUS MODE, MUX FUNCTION
SYNC
Port A
Port D
Port Y
INVALID
DATA
DATA1
DATA2
INVALID DATA
DATA3
INVALID DATA
DATA1
DATA2
DATA3
DATA3
t
PLH,
t
PHL
t
PLH,
t
PHL
t
ASO
t
PLZ,
t
PHZ
t
PZL,
t
PZH
SEL
0
, SEL
1
OE
0
, OE
1
Example: Port A / Port D to Port Y
9
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
INDUSTRIAL TEMPERATURE RANGE
I
BH
+500
Sinking
Current
( + )
I
BHL
I
BH
I
BHH
+60
+20
60
20
+60
I
BHL
0.8V
2V
V
IH
60 I
BHL
V
IL
Sourcing
Current
( )
I
BH
500
Vcc
+20 I
BH
20 I
BH
Voltage
V
T
V-I CHARACTERISTICS OF BUS-HOLD CIRCUIT
V
T
Threshold Voltage
1.5V
V
IL
.8 V
IH
2V
ACTIVE TERMINATOR OR "BUS-HOLD" CIRCUIT
The Active Terminator circuit, also known as the bus-hold circuit, is configured as a "weak latch" with positive feedback. When connected to a TTL or CMOS
input port, the bus-hold circuit holds the last logic state at the input when the input is "disconnected" from the driver. When the output of a device connected
to such an input attempts a logic level transition, it will overdrive the bus-hold circuit. The primary benefit of a bus-hold circuit is that it prevents CMOS inputs
from floating, a situation which should be avoided to prevent spurious switching of inputs and unnecessary power dissipation. Bus-hold is a better solution than
the traditional approach of using resistive termination to Vcc or GND to prevent bus floating, because the bus-hold circuit does not consume any static power.
This figure shows the input V-I characteristics of a typical bus-hold implementation. The input characteristics resemble a resistor. As the input voltage is
increased from 0 volts, the input "sink" current increases linearly. When the TTL threshold of the circuit is reached (typically 1.5 volts), the latch changes the
logic state due to positive feedback and the direction of the current is reversed. As the input voltage is further increased towards Vcc, the input "source" current
begins to decrease, reaching the lowest level at V
IN
= Vcc.
10
INDUSTRIAL TEMPERATURE RANGE
IDTQS3ST253
HIGH-SPEED CMOS SYNCHROSWITCH DUAL 4:1 MUX/DEMUX
ORDERING INFORMATION
CORPORATE HEADQUARTERS
for SALES:
for Tech Support:
2975 Stender Way
800-345-7015 or 408-727-6116
logichelp@idt.com
Santa Clara, CA 95054
fax: 408-492-8674
(408) 654-6459
www.idt.com
IDTQS
XXXXX
XX
Package
Device Type
Blank
Industrial (-40C to +85C)
Quarter Size Small Outline Package
Q
3ST253
High Speed CMOS SynchroSwitch Dual 4:1
Mux/Demux with Active Terminators
X
Process
PDF 
ZIP