FAST CMOS OCTAL
BIDIRECTIONAL
TRANSCEIVERS
Integrated Device Technology, Inc.
IDT54/74FCT245T/AT/CT/DT - 2245T/AT/CT
IDT54/74FCT640T/AT/CT
IDT54/74FCT645T/AT/CT/DT
FEATURES:
• Common features:
– Low input and output leakage
≤1µA
(max.)
– CMOS power levels
– True TTL input and output compatibility
– V
OH
= 3.3V (typ.)
– V
OL
= 0.3V (typ.)
– Meets or exceeds JEDEC standard 18 specifications
– Product available in Radiation Tolerant and Radiation
Enhanced versions
– Military product compliant to MIL-STD-883, Class B
and DESC listed (dual marked)
– Available in DIP, SOIC, SSOP, QSOP, CERPACK
and LCC packages
• Features for FCT245T/FCT640T/FCT645T:
– Std., A, C and D speed grades
– High drive outputs (-15mA I
OH
, 64mA I
OL
)
• Features for FCT2245T:
– Std., A and C speed grades
– Resistor outputs (-15mA I
OH
, 12mA I
OL
Com.)
(-12mA I
OH
, 12mA I
OL
Mil.)
– Reduced system switching noise
DESCRIPTION:
The IDT octal bidirectional transceivers are built using an
advanced dual metal CMOS technology. The FCT245T/
FCT2245T, FCT640T and FCT645T are designed for asyn-
chronous two-way communication between data buses. The
transmit/receive (T/
R
) input determines the direction of data
flow through the bidirectional transceiver. Transmit (active
HIGH) enables data from A ports to B ports, and receive
(active LOW) from B ports to A ports. The output enable (
OE
)
input, when HIGH, disables both A and B ports by placing
them in HIGH Z condition.
The FCT245T/FCT2245T and FCT645T transceivers have
non-inverting outputs. The FCT640T has inverting outputs.
The FCT2245T has balanced drive outputs with current
limiting resistors. This offers low ground bounce, minimal
undershoot and controlled output fall times- reducing the need
for external series terminating resistors. The FCT2xxxT parts
are plug-in replacements for FCTxxxT parts.
FUNCTIONAL BLOCK DIAGRAM
T/R
OE
A
0
B
0
A
1
B
1
A
2
B
2
A
3
B
3
A
4
B
4
A
5
B
5
A
6
B
6
A
7
B
7
FCT245T/2245T, FCT645T are non-inverting options.
FCT640T is the inverting options.
2539 drw 01
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
PIN CONFIGURATIONS
T/R
A
0
A
1
A
2
A
3
A
4
A
5
A
6
A
7
GND
1
2
3
4
5
6
7
8
9
10
20
19
P20-1
D20-1
SO20-2
SO20-7*
SO20-8**
&
E20-1
18
17
16
15
14
13
12
11
Vcc
OE
B
0
B
1
B
2
B
3
B
4
B
5
B
6
B
7
2539 drw 02
DIP/SOIC/SSOP/QSOP/CERPACK
TOP VIEW
*FCT245T/2245T, FCT645T only.
**FCT245T/2245T, FCT640T
INDEX
A
2
A
3
A
4
A
5
A
6
A
1
A
0
T/R
Vcc
OE
3
4
5
6
7
8
2
20 19
18
1
17
16
15
14
9 10 11 12 13
L20-2
B
0
B
1
B
2
B
3
B
4
A
7
GND
B
7
B
6
B
5
2539 drw 03
LCC
TOP VIEW
MILITARY AND COMMERCIAL TEMPERATURE RANGES
©1995
Integrated Device Technology, Inc.
AUGUST 1995
DSC-4611/4
6.9
1
IDT54/74FCT245T/AT/CT/DT - 2245T/AT/CT, IDT54/74FCT640T/AT/CT, IDT54/74FCT645T/AT/CT/DT
FAST CMOS OCTAL BIDIRECTIONAL TRANSCEIVERS
MILITARY AND COMMERCIAL TEMPERATURE RANGES
PIN DESCRIPTION
Pin Names
FUNCTION TABLE
(2)
Inputs
OE
T/
R
A
0
-A
7
B
0
-B
7
Description
Output Enable Input (Active LOW)
Transmit/Receive Input
Side A Inputs or 3-State Outputs
Side B Inputs or 3-State Outputs
2539 tbl 01
OE
L
L
H
T/
R
L
H
X
Outputs
Bus B Data to Bus A
(1)
Bus B Data to Bus B
(1)
High Z State
2539 tbl 02
NOTES:
1. 640 is inverting from input to output.
2. H = HIGH Voltage Level
L = LOW Voltage Level
X = Don't Care
ABSOLUTE MAXIMUM RATINGS
(1)
Symbol
Rating
Commercial
V
TERM(2)
Terminal Voltage
–0.5 to +7.0
with Respect to
GND
V
TERM(3)
Terminal Voltage
–0.5 to
with Respect to
V
CC
+0.5
GND
T
A
Operating
0 to +70
Temperature
T
BIAS
Temperature
–55 to +125
Under Bias
T
STG
Storage
–55 to +125
Temperature
P
T
Power Dissipation
0.5
I
OUT
DC Output
Current
–60 to +120
Military
–0.5 to +7.0
Unit
V
CAPACITANCE
(TA = +25°C, F = 1.0MHZ)
Symbol
Parameter
(1)
C
IN
Input
Capacitance
C
OUT
Output
Capacitance
Conditions
V
IN
= 0V
V
OUT
= 0V
Typ.
6
8
Max. Unit
10
pF
12
pF
2539 lnk 04
–0.5 to
V
CC
+0.5
–55 to +125
–65 to +135
–65 to +150
0.5
–60 to +120
V
°C
°C
°C
W
mA
NOTE:
1. This parameter is measured at characterization but not tested.
2539 lnk 03
NOTES:
1. Stresses greater than those listed under ABSOLUTE MAXIMUM RAT-
INGS 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. No terminal voltage may exceed
V
CC
by +0.5V unless otherwise noted.
2. Input and V
CC
terminals only.
3. Outputs and I/O terminals only.
6.9
2
IDT54/74FCT245T/AT/CT/DT - 2245T/AT/CT, IDT54/74FCT640T/AT/CT, IDT54/74FCT645T/AT/CT/DT
FAST CMOS OCTAL BIDIRECTIONAL TRANSCEIVERS
MILITARY AND COMMERCIAL TEMPERATURE RANGES
DC ELECTRICAL CHARACTERISTICS OVER OPERATING RANGE
Following Conditions Apply Unless Otherwise Specified:
Commercial: T
A
= 0°C to +70°C, V
CC
= 5.0V
±
5%; Military: T
A
= –55°C to +125°C, V
CC
= 5.0V
±
10%
Symbol
V
IH
V
IL
I
I H
I
I L
I
OZH
I
OZL
I
I
V
IK
V
H
I
CC
Parameter
Input HIGH Level
Input LOW Level
Input HIGH Current
(4)
Input LOW Current
(4)
High Impedance Output Current
(3-State Output pins)
(4)
Input HIGH Current
(4)
Clamp Diode Voltage
Input Hysteresis
Quiescent Power Supply Current
V
CC
= Min., I
IN
= –18mA
—
Test Conditions
(1)
Guaranteed Logic HIGH Level
Guaranteed Logic LOW Level
V
CC
= Max.
V
CC
= Max.
V
I
= 2.7V
V
I
= 0.5V
V
O
= 2.7V
V
O
= 0.5V
V
CC
= Max., V
I
= V
CC
(Max.)
Min.
2.0
—
—
—
—
—
—
—
—
—
Typ.
(2)
—
—
—
—
—
—
—
–0.7
200
0.01
Max.
—
0.8
±1
±1
±1
±1
±1
–1.2
—
1
Unit
V
V
µA
µA
µA
V
mV
mA
2539 lnk 05
V
CC
= Max., V
IN
= GND or V
CC
OUTPUT DRIVE CHARACTERISTICS FOR FCT245T/640T/645T
Symbol
V
OH
Parameter
Output HIGH Voltage
Test Conditions
(1)
V
CC
= Min.
I
OH
= –6mA MIL.
V
IN
= V
IH
or V
IL
I
OH
= –8mA COM'L.
I
OH
= –12mA MIL.
I
OH
= –15mA COM'L.
V
CC
= Min.
I
OL
= 48mA MIL.
V
IN
= V
IH
or V
IL
I
OL
= 64mA COM'L.
V
CC
= Max., V
O
= GND
(3)
Min.
2.4
2.0
—
–60
Typ.
(2)
3.3
3.0
0.3
–120
Max.
—
—
0.55
–225
Unit
V
V
V
mA
2539 lnk 06
V
OL
I
OS
Output LOW Voltage
Short Circuit Current
OUTPUT DRIVE CHARACTERISTICS FOR FCT2245T
Symbol
I
ODL
I
ODH
V
OH
V
OL
Parameter
Output LOW Current
Output HIGH Current
Output HIGH Voltage
Output LOW Voltage
Test Conditions
(1)
V
CC
= 5V, V
IN
= V
IH
or V
IL,
V
OUT
= 1.5V
(3)
V
CC
= 5V, V
IN
= V
IH
or V
IL,
V
OUT
= 1.5V
(3)
V
CC
= Min.
V
IN
= V
IH
or V
IL
V
CC
= Min.
V
IN
= V
IH
or V
IL
I
OH
= –12mA MIL.
I
OH
= –15mA COM'L.
I
OL
= 12mA
Min.
16
–16
2.4
—
Typ.
(2)
48
–48
3.3
0.3
Max.
—
—
—
0.50
Unit
mA
mA
V
V
2539 lnk 07
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 Vcc = 5.0V, +25°C ambient.
3. Not more than one output should be shorted at one time. Duration of the short circuit test should not exceed one second.
4. The test limit for this parameter is
±5µA
at T
A
= –55°C.
6.9
3
IDT54/74FCT245T/AT/CT/DT - 2245T/AT/CT, IDT54/74FCT640T/AT/CT, IDT54/74FCT645T/AT/CT/DT
FAST CMOS OCTAL BIDIRECTIONAL TRANSCEIVERS
MILITARY AND COMMERCIAL TEMPERATURE RANGES
POWER SUPPLY CHARACTERISTICS
Symbol
∆I
CC
I
CCD
Parameter
Quiescent Power Supply Current
TTL Inputs HIGH
Dynamic Power Supply
Current
(4)
Test Conditions
(1)
V
CC
= Max.
V
IN
= 3.4V
(3)
V
CC
= Max.
Outputs Open
OE
= T/
R
= GND
One Input Toggling
50% Duty Cycle
V
CC
= Max.
Outputs Open
fi = 10MHz
50% Duty Cycle
Min.
—
—
—
Typ.
(2)
0.5
0.15
0.06
Max.
2.0
0.25
0.12
Unit
mA
mA/
MHz
V
IN
= V
CC
FCTxxxT
V
IN
= GND
FCT2xxxT
I
C
Total Power Supply Current
(6)
V
IN
= V
CC
FCTxxxT
—
—
—
1.5
0.6
1.8
0.9
3.5
2.2
4.5
3.2
6.0
(5)
3.4
(5)
14.0
(5)
11.4
(
5)
mA
V
IN
= GND FCT2xxxT
V
IN
= 3.4
FCTxxxT
OE
= T/
R
= GND
One Bit Toggling
V
CC
= Max.
Outputs Open
fi = 2.5MHz
50% Duty Cycle
V
IN
= GND FCT2xxxT
V
IN
= V
CC
FCTxxxT
—
—
—
—
3.0
1.2
5.0
3.2
V
IN
= GND FCT2xxxT
V
IN
= 3.4
FCTxxxT
OE
= T/
R
= GND
Eight Bits Toggling
V
IN
= GND FCT2xxxT
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, +25°C 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 the I
CC
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
CP/
2 + f
i
N
i
)
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
i
= Number of Inputs at f
i
All currents are in milliamps and all frequencies are in megahertz.
2539 tbl 08
6.9
4
IDT54/74FCT245T/AT/CT/DT - 2245T/AT/CT, IDT54/74FCT640T/AT/CT, IDT54/74FCT645T/AT/CT/DT
FAST CMOS OCTAL BIDIRECTIONAL TRANSCEIVERS
MILITARY AND COMMERCIAL TEMPERATURE RANGES
SWITCHING CHARACTERISTICS OVER OPERATING RANGE
FCT245T
FCT2245T
Com'l.
Symbol
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
t
PZH
t
PZL
t
PHZ
t
PLZ
Parameter
Propagation Delay
A to B, B to A
Output Enable Time
OE
to A or B
Output Disable Time
OE
to A or B
Output Enable Time
T/
R
to A or B
(3)
Output Disable Time
T/
R
to A or B
(3)
Conditions
(1)
C
L
= 50 pF
R
L
= 500
Ω
Min.
(2)
1.5
1.5
1.5
1.5
1.5
Max.
7.0
9.5
7.5
9.5
7.5
Mil.
Min
.
(2)
1.5
1.5
1.5
1.5
1.5
Max.
7.5
10.0
10.0
10.0
10.0
Min
.
(2)
1.5
1.5
1.5
1.5
1.5
FCT245AT
FCT2245AT
Com'l.
Max.
4.6
6.2
5.0
6.2
5.0
Mil.
Min.
(2)
1.5
1.5
1.5
1.5
1.5
Max.
4.9
6.5
6.0
6.5
6.0
Unit
ns
ns
ns
ns
ns
2534 tbl 09
FCT245CT
FCT2245CT
Com'l.
Symbol
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
t
PZH
t
PZL
t
PHZ
t
PLZ
Parameter
Propagation Delay
A to B, B to A
Output Enable Time
OE
to A or B
Output Disable Time
OE
to A or B
Output Enable Time
T/
R
to A or B
(3)
Output Disable Time
T/
R
to A or B
(3)
Conditions
(1)
C
L
= 50 pF
R
L
= 500Ω
Min.
(2)
1.5
1.5
1.5
1.5
1.5
Max.
4.1
5.8
4.8
5.8
4.8
Mil.
Min
.
(2)
1.5
1.5
1.5
1.5
1.5
Max.
4.5
6.2
5.2
6.2
5.2
Min
.
(2)
1.5
1.5
1.5
1.5
1.5
FCT245DT
Com'l.
Max.
3.8
5.0
4.3
5.0
4.3
Mil.
Min.
(2)
—
—
—
—
—
Max.
—
—
—
—
—
Unit
ns
ns
ns
ns
ns
2534 tbl 10
SWITCHING CHARACTERISTICS OVER OPERATING RANGE
FCT640T
Com'l.
Symbol
t
PLH
t
PHL
t
PZH
t
PZL
t
PHZ
t
PLZ
t
PZH
t
PZL
t
PHZ
t
PLZ
Parameter
Propagation Delay
A to B, B to A
Output Enable Time
OE
to A or B
Output Disable Time
OE
to A or B
Output Enable Time
T/
R
to A or B
(3)
Output Disable Time
T/
R
to A or B
(3)
Mil.
FCT640AT
Com'l.
Mil.
FCT640CT
Com'l.
Mil.
Conditions
(1)
Min
.
(2)
Max. Min.
(2)
Max. Min
.
(2)
Max. Min.
(2)
Max. Min.
(2)
Max. Min.
(2)
Max.
Unit
2.0 7.0 2.0
8.0 1.5 5.0 1.5
5.3 1.5 4.4 1.5
4.7 ns
C
L
= 50 pF
R
L
= 500Ω
2.0 13.0 2.0 16.0 1.5 6.2 1.5
6.5 1.5 5.8 1.5
6.2 ns
2.0
2.0
2.0
10.0
13.0
10.0
2.0
2.0
2.0
12.0
16.0
12.0
1.5
1.5
1.5
5.0
6.2
5.0
1.5
1.5
1.5
6.0
6.5
6.0
1.5
1.5
1.5
4.8
5.8
4.8
1.5
1.5
1.5
5.2
6.2
5.2
ns
ns
ns
NOTES:
1. See test circuit and waveforms.
2. Minimum limits are guaranteed but not tested on Propagation Delays.
3. This parameter is guaranteed but not tested.
2534 tbl 11
6.9
5
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