1
INDUSTRIAL TEMPERATURE RANGE
IDT74FST6800
10-BIT BUS SWITCH WITH PRECHARGED OUTPUTS
JANUARY 2004
INDUSTRIAL TEMPERATURE RANGE
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
2004 Integrated Device Technology, Inc.
DSC-5519/2
FEATURES:
Bus switches provide zero delay paths
Low switch on-resistance: 7
TTL-compatible input and output levels
ESD > 2000V per MIL-STD-883, Method 3015; > 200V using
machine model (C = 200pF, R = 0)
Available in QSOP and TSSOP packages
FUNCTIONAL BLOCK DIAGRAM
QSOP/ TSSOP
TOP VIEW
PIN CONFIGURATION
IDT74FST6800
10-BIT BUS SWITCH
WITH PRECHARGED
OUTPUTS
DESCRIPTION:
The FST6800 belongs to IDT's family of Bus switches. Bus switch devices
perform the function of connecting or isolating two ports without providing
any inherent current sink or source capability. Thus they generate little or
no noise of their own while providing a low resistance path for an external
driver. These devices connect input and output ports through an n-channel
FET. When the gate-to-source junction of this FET is adequately forward-
biased the device conducts and the resistance between input and output
ports is small. Without adequate bias on the gate-to-source junction of the
FET, the FET is turned off, therefore with no V
CC
applied, the device has
hot insertion capability.
The low on-resistance and simplicity of the connection between input and
output ports reduces the delay in this path to close to zero.
The FST6800 provides a 10-Bit TTL-compatible interface. The ON pin
serves as the enable pin. When ON is high, A and B ports are isolated and
B outputs are precharged to the BIASV voltage, through the equivalent of
a 10K
resistor.
A
1
A
10
B
10
B
1
BIASV
ON
A
1
A
3
A
4
A
6
A
9
A
2
A
5
A
7
A
8
A
10
GND
V
CC
B
1
B
2
B
3
B
4
B
5
B
6
B
8
B
9
B
10
BIASV
B
7
15
13
14
24
23
17
18
19
20
21
22
16
1
2
3
4
5
6
7
8
9
10
12
11
ON
2
INDUSTRIAL TEMPERATURE RANGE
IDT74FST6800
10-BIT BUS SWITCH WITH PRECHARGED OUTPUTS
Symbol
Description
Max
Unit
V
TERM
(2)
Terminal Voltage with Respect to GND
0.5 to +7
V
T
STG
Storage Temperature
65 to +150
C
I
OUT
Maximum Continuous Channel Current
128
mA
ABSOLUTE MAXIMUM RATINGS
(1)
NOTES:
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, Control, and Switch terminals.
Symbol
Parameter
Conditions
(2)
Typ. Unit
C
IN
Control Input Capacitance
4
pF
C
I/O
Switch Input/Output Capacitance
Switch Off
pF
CAPACITANCE
(1)
NOTES:
1. Capacitance is characterized but not tested.
2. T
A
= 25C, f = 1MHz, V
IN
= 0V, V
OUT
= 0V.
Pin Names
I/O
Description
A
1-10
, B
1-10
I/O
Buses A, B
ON
I
Bus Switch Enable (Active LOW)
BIASV
I
BIAS Voltage
PIN DESCRIPTION
NOTE:
1. H = HIGH Voltage Level
L = LOW Voltage Level
FUNCTION TABLE
(1)
ON
B
1-10
Description
L
A
1-10
Connect
H
BIASV
Precharge
Symbol
Parameter
Test Conditions
(1)
Min.
Typ.
(2)
Max.
Unit
V
IH
Input HIGH Voltage
Guaranteed Logic HIGH for Control Inputs
2
--
--
V
V
IL
Input LOW Voltage
Guaranteed Logic LOW for Control Inputs
--
--
0.8
V
I
IH
Input HIGH Current
V
CC
= Max.
V
I
= V
CC
--
--
1
A
I
IL
Input LOW Current
V
I
= GND
--
--
1
I
O
Precharge Output Current
V
CC
= Min., BIASV = 2.4V, V
O
= 0V
0.15
--
--
mA
I
OZH
High Impedance Output Current
V
CC
= Max.
V
O
= V
CC
--
--
1
A
I
OZL
(3-State Output Pins)
V
O
= GND
--
--
1
I
OS
Short Circuit Current
V
CC
= Min., V
O
= GND
(3)
--
300
--
mA
V
IK
Clamp Diode Voltage
V
CC
= Min., I
IN
= 18mA
--
0.7
1.2
V
R
ON
Switch On Resistance
(4)
V
CC
= 4.75V, V
IN
= 0.0V I
ON
= 64mA
--
--
7
V
CC
= 4.75V, V
IN
= 2.4V I
ON
= 15mA
--
--
15
I
OFF
Input/Output Power Off Leakage
V
CC
= 0V, V
IN
or V
O
4.5V
--
--
1
A
I
CC
Quiescent Power Supply Current
V
CC
= Max., V
I
= GND or V
CC
--
0.1
3
A
DC ELECTRICAL CHARACTERISTICS OVER OPERATING RANGE
Following Conditions Apply Unless Otherwise Specified:
Industrial: T
A
= 40C to +85C, V
CC
= 5.0V 5%, BIASV = 0 to V
CC
NOTES:
1. For conditions shown as Max. or Min., use appropriate value specified under Electrical Characteristics for the applicable device type.
2. Typical values are at V
CC
= 5.0V, +25C ambient.
3. Not more than one output should be tested at one time. Duration of the test should not exceed one second.
4. Measured by voltage drop between ports at indicated current through the switch.
3
INDUSTRIAL TEMPERATURE RANGE
IDT74FST6800
10-BIT BUS SWITCH WITH PRECHARGED OUTPUTS
Symbol
Parameter
Test Conditions
(1)
Min.
Typ.
(2)
Max.
Unit
I
CC
Quiescent Power Supply Current
V
CC
= Max.
--
0.5
1.5
mA
TTL Inputs HIGH
V
IN
= 3.4V
(3)
I
CCD
Dynamic Power Supply
V
CC
= Max., Outputs Open
V
IN
= V
CC
--
30
40
A/
Current
(4)
Enable Pin Toggling
V
IN
= GND
MHz/
50% Duty Cycle
Enable
I
C
Total Power Supply Current
(6)
V
CC
= Max., Outputs Open
V
IN
= V
CC
--
3
4
mA
Enable Pin Toggling
V
IN
= GND
(Ten Switches Toggling)
f
i
= 10MHz
V
IN
= 3.4V
--
3.3
4.8
50% Duty Cycle
V
IN
= GND
POWER SUPPLY CHARACTERISTICS
NOTES:
1. For conditions shown as Max. or Min., use appropriate value specified under Electrical Characteristics for the applicable device type.
2. Typical values are at V
CC
= 5.0V, +25C ambient.
3. Per TTL driven input (V
IN
= 3.4V). All other inputs at V
CC
or GND.
4. This parameter is not directly testable, but is derived for use in Total Power Supply Calculations.
5. Values for these conditions are examples of Icc formula. These limits are guaranteed but not tested.
6. I
C
= I
QUIESCENT
+ I
INPUTS
+ I
DYNAMIC
I
C
= I
CC
+
I
CC
D
H
N
T
+ I
CCD
(f
i
N)
I
CC
= Quiescent Current
I
CC
= Power Supply Current for a TTL High Input (V
IN
= 3.4V)
D
H
= Duty Cycle for TTL Inputs High
N
T
= Number of TTL Inputs at D
H
I
CCD
= Dynamic Current Caused by an Input Transition Pair (HLH or LHL)
f
CP
= Clock Frequency for Register Devices (zero for non-register devices)
f
i
= Input Frequency
N = Number of SwitchesToggling at f
i
All currents are in milliamps and all frequencies are in megahertz
SWITCHING CHARACTERISTICS OVER OPERATING RANGE
Following Conditions Apply Unless Otherwise Specified:
Industrial: T
A
= -40C to +85C, V
CC
= 5.0V 5%
Symbol
Description
Condition
(1)
Min.
(2)
Typ.
Max.
Unit
t
PLH
Data Propagation Delay
C
L
= 50pF
--
--
0.25
ns
t
PHL
Ax, Bx to Bx, Ax
(3,4)
R
L
= 500
t
PZH
Switch Turn On Delay
1.5
--
6.5
ns
t
PZL
ON to Ax, Bx
t
PHZ
Switch Turn Off Delay
1.5
--
5.5
ns
t
PLZ
ON to Ax, Bx
(3)
NOTES:
1. See test circuit and waveforms.
2. Minimum limits guaranteed but not tested.
3. This parameter is guaranteed by design but not tested.
4. 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 constant for the switch alone
is of the order of 0.25 ns for 50 pF load. Since this time is constant and much smaller than the rise/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.
4
INDUSTRIAL TEMPERATURE RANGE
IDT74FST6800
10-BIT BUS SWITCH WITH PRECHARGED OUTPUTS
Pulse
Generator
R
T
D.U.T
.
V
CC
V
IN
C
L
V
OUT
50pF
500
500
7.0V
3V
1.5V
0V
3V
1.5V
0V
3V
1.5V
0V
3V
1.5V
0V
DATA
INPUT
TIMING
INPUT
ASYNCHRONOUS CONTROL
PRESET
CLEAR
ETC.
SYNCHRONOUS CONTROL
t
SU
t
H
t
REM
t
SU
t
H
HIGH-LOW-HIGH
PULSE
LOW-HIGH-LOW
PULSE
t
W
1.5V
1.5V
SAME PHASE
INPUT TRANSITION
3V
1.5V
0V
1.5V
V
OH
t
PLH
OUTPUT
OPPOSITE PHASE
INPUT TRANSITION
3V
1.5V
0V
t
PLH
t
PHL
t
PHL
V
OL
CONTROL
INPUT
3V
1.5V
0V
3.5V
0V
OUTPUT
NORMALLY
LOW
OUTPUT
NORMALLY
HIGH
SWITCH
CLOSED
SWITCH
OPEN
V
OL
0.3V
0.3V
t
PLZ
t
PZL
t
PZH
t
PHZ
3.5V
0V
1.5V
1.5V
ENABLE
DISABLE
V
OH
PRESET
CLEAR
CLOCK ENABLE
ETC.
Octal Link
Octal Link
Octal Link
Octal Link
Octal Link
TEST CIRCUITS AND WAVEFORMS
Propagation Delay
Test Circuits for All Outputs
Enable and Disable Times
Set-up, Hold, and Release Times
Pulse Width
NOTES:
1. Diagram shown for input Control Enable-LOW and input Control Disable-HIGH.
2. Pulse Generator for All Pulses: Rate
1.0MHz; t
F
2.5ns; t
R
2.5ns.
Test
Switch
Open Drain
Disable Low
Closed
Enable Low
All Other Tests
Open
SWITCH POSITION
DEFINITIONS:
C
L
= Load capacitance: includes jig and probe capacitance.
R
T
= Termination resistance: should be equal to Z
OUT
of the Pulse Generator.
5
INDUSTRIAL TEMPERATURE RANGE
IDT74FST6800
10-BIT BUS SWITCH WITH PRECHARGED OUTPUTS
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
IDT XX
Temp. Range
XX
Device Type
X
Package
74
-
40
C to +85
C
Q
PG
6800
Quarter-size Small Outline Package
Thin Shrink Small Outline Package
10-Bit Bus Switch with Precharged Outputs
FST
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