TI SN74HCT646DW

SN54HCT646, SN74HCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCLS178B – MARCH 1984 – REVISED MAY 1997
D
Inputs Are TTL-Voltage Compatible
Independent Registers for A and B Buses
Multiplexed Real-Time and Stored Data
True Data Paths
High-Current 3-State Outputs Can Drive up
to 15 LSTTL Loads
Package Options Include Plastic
Small-Outline (DW) and Ceramic Flat (W)
Packages, Ceramic Chip Carriers (FK), and
Standard Plastic (NT) and Ceramic (JT)
300-mil DIPs
SN54HCT646 . . . JT OR W PACKAGE
SN74HCT646 . . . DW OR NT PACKAGE
(TOP VIEW)
CLKAB
SAB
DIR
A1
A2
A3
A4
A5
A6
A7
A8
GND
description
Output-enable (OE) and direction-control (DIR)
inputs control the transceiver functions. In the
transceiver mode, data present at the
high-impedance port can be stored in either or
both registers.
The select-control (SAB and SBA) inputs can
multiplex stored and real-time (transparent mode)
data. DIR determines which bus receives data
when OE is active (low). In the isolation mode (OE
high), A data can be stored in one register and /or
B data can be stored in the other register.
24
2
23
3
22
4
21
5
20
6
19
7
18
8
17
9
16
10
15
11
14
12
13
VCC
CLKBA
SBA
OE
B1
B2
B3
B4
B5
B6
B7
B8
DIR
SAB
CLKAB
NC
VCC
CLKBA
SBA
SN54HCT646 . . . FK PACKAGE
(TOP VIEW)
A1
A2
A3
NC
A4
A5
A6
5
4
2 1 28 27 26
25
6
24
7
23
8
22
9
21
10
20
11
3
19
12 13 14 15 16 17 18
A7
A8
GND
NC
B8
The ’HCT646 consist of bus-transceiver circuits
with 3-state outputs, D-type flip-flops, and control
circuitry arranged for multiplexed transmission of
data directly from the input bus or from the internal
registers. Data on the A or B bus is clocked into the
registers on the low-to-high transition of the
appropriate clock (CLKAB or CLKBA) input.
Figure 1 illustrates the four fundamental busmanagement functions that can be performed
with the ’HCT646.
1
OE
B1
B2
NC
B3
B4
B5
B7
B6
D
D
D
D
D
NC – No internal connection
When an output function is disabled, the input function is still enabled and can be used to store and transmit
data. Only one of the two buses, A or B, can be driven at a time.
The SN54HCT646 is characterized for operation over the full military temperature range of – 55°C to 125°C.
The SN74HCT646 is characterized for operation from –40°C to 85°C.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright  1997, Texas Instruments Incorporated
UNLESS OTHERWISE NOTED this document contains PRODUCTION
DATA information current as of publication date. Products conform to
specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all
parameters.
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1
SN54HCT646, SN74HCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
21
OE
L
3
DIR
L
1
23
CLKAB CLKBA
X
X
2
SAB
X
BUS B
BUS A
BUS A
BUS B
SCLS178B – MARCH 1984 – REVISED MAY 1997
22
SBA
L
21
OE
L
3
DIR
H
3
DIR
X
X
X
1
23
CLKAB CLKBA
X
↑
X
↑
↑
↑
2
SAB
X
X
X
22
SBA
X
X
X
21
OE
L
L
22
SBA
X
BUS B
3
DIR
L
H
STORAGE FROM
A, B, OR A AND B
1
CLKAB
X
H or L
23
CLKBA
H or L
X
2
SAB
X
H
TRANSFER STORED DATA
TO A AND/OR B
Pin numbers shown are for the DW, JT, NT, and W packages.
Figure 1. Bus-Management Functions
2
2
SAB
L
BUS A
BUS A
21
OE
X
X
H
23
CLKBA
X
REAL-TIME TRANSFER
BUS A TO BUS B
BUS B
REAL-TIME TRANSFER
BUS B TO BUS A
1
CLKAB
X
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22
SBA
H
X
SN54HCT646, SN74HCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCLS178B – MARCH 1984 – REVISED MAY 1997
FUNCTION TABLE
INPUTS
DATA I/O
OPERATION OR FUNCTION
OE
DIR
CLKAB
CLKBA
SAB
SBA
A1– A8
B1– B8
X
X
↑
X
X
X
Input
Unspecified†
X
X
X
↑
X
X
Unspecified†
Input
Store A, B unspecified†
Store B, A unspecified†
H
X
↑
↑
X
X
Input
Input
Store A and B data
H
X
H or L
H or L
X
X
Input disabled
Input disabled
Isolation, hold storage
L
L
X
X
X
L
Output
Input
Real-time B data to A bus
L
L
X
H or L
X
H
Output
Input
Stored B data to A bus
L
H
X
X
L
X
Input
Output
Real-time A data to B bus
L
H
H or L
X
H
X
Input
Output
Stored A data to B bus
† The data-output functions can be enabled or disabled by various signals at OE and DIR. Data-input functions are always enabled; i.e., data at
the bus terminals is stored on every low-to-high transition of the clock inputs.
logic symbol‡
OE
DIR
CLKBA
SBA
CLKAB
SAB
A1
21
3
23
22
1
2
G3
3 EN1 [BA]
3 EN2 [AB]
C4
G5
C6
G7
≥1
4
1
7
1
A3
A4
A5
A6
A7
A8
20
B1
5 1
6D
A2
4D
5
≥1
2
7
5
19
6
18
7
17
8
16
9
15
10
14
11
13
B2
B3
B4
B5
B6
B7
B8
‡ This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for the DW, JT, NT, and W packages.
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3
SN54HCT646, SN74HCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCLS178B – MARCH 1984 – REVISED MAY 1997
logic diagram (positive logic)
OE
DIR
CLKBA
SBA
CLKAB
SAB
21
3
23
22
1
2
One of Eight Channels
1D
C1
A1
4
20
B1
1D
C1
To Seven Other Channels
Pin numbers shown are for the DW, JT, NT, and W packages.
absolute maximum ratings over operating free-air temperature range†
Supply voltage range, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 7 V
Input clamp current, IIK (VI < 0 or VI > VCC) (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20 mA
Output clamp current, IOK (VO < 0 or VO > VCC) (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±20 mA
Continuous output current, IO (VO = 0 to VCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±35 mA
Continuous current through VCC or GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±70 mA
Package thermal impedance, θJA (see Note 2): DW package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81°C/W
NT package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67°C/W
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTES: 1. The input and output voltage ratings may be exceeded if the input and output current ratings are observed.
2. The package thermal impedance is calculated in accordance with JESD 51, except for through-hole packages, which use a trace
length of zero.
4
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SN54HCT646, SN74HCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCLS178B – MARCH 1984 – REVISED MAY 1997
recommended operating conditions
SN54HCT646
SN74HCT646
MIN
NOM
MAX
MIN
NOM
MAX
4.5
5
5.5
4.5
5
5.5
UNIT
VCC
VIH
Supply voltage
VIL
VI
Low-level input voltage
0
0.8
0
0.8
V
Input voltage
0
0
Output voltage
0
0
VCC
VCC
V
VO
tt
VCC
VCC
0
500
0
500
ns
TA
Operating free-air temperature
–55
125
–40
85
°C
High-level input voltage
VCC = 4.5 V to 5.5 V
VCC = 4.5 V to 5.5 V
2
Input transition (rise and fall) time
2
V
V
V
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
VCC
VOH
VI = VIH or VIL
IOH = –20 µA
IOH = –6 mA
45V
4.5
VOL
VI = VIH or VIL
IOL = 20 µA
IOL = 6 mA
45V
4.5
II
IOZ
Control inputs
A or B
ICC
∆ICC†
Ci
MIN
TA = 25°C
TYP
MAX
SN54HCT646
MIN
MAX
SN74HCT646
MIN
4.4
4.499
4.4
4.4
3.98
4.3
3.7
3.84
MAX
UNIT
V
0.001
0.1
0.1
0.1
0.17
0.26
0.4
0.33
±1000
±1000
nA
V
VI = VCC or 0
VO = VCC or 0
5.5 V
±0.1
±100
5.5 V
±0.01
±0.5
±10
±5
µA
VI = VCC or 0, IO = 0
One input at 0.5 V or 2.4 V,
Other inputs at 0 or VCC
5.5 V
8
160
80
µA
1.4
2.4
3
2.9
mA
3
10
10
10
pF
5.5 V
4.5 V
to 5.5 V
Control inputs
† This is the increase in supply current for each input that is at one of the specified TTL voltage levels rather than 0 V or VCC.
timing requirements over recommended operating free-air temperature range (unless otherwise
noted)
VCC
fclock
l k
Clock frequency
tw
Pulse duration,
duration CLKBA or CLKAB high or low
tsu
Set p time,
Setup
time A before CLKAB↑ or B before CLKBA↑
th
time A after CLKAB↑ or B after CLKBA↑
Hold time,
TA = 25°C
MIN
MAX
SN54HCT646
SN74HCT646
MIN
MAX
MIN
MAX
4.5 V
0
31
0
22
0
27
5.5 V
0
36
0
24
0
29
4.5 V
16
23
19
5.5 V
14
21
17
4.5 V
20
30
25
5.5 V
18
27
23
4.5 V
5
5
5
5.5 V
5
5
5
UNIT
MHz
ns
ns
ns
PRODUCT PREVIEW information concerns products in the formative or
design phase of development. Characteristic data and other
specifications are design goals. Texas Instruments reserves the right to
change or discontinue these products without notice.
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SN54HCT646, SN74HCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCLS178B – MARCH 1984 – REVISED MAY 1997
switching characteristics over recommended operating free-air temperature range, CL = 50 pF
(unless otherwise noted) (see Figure 2)
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
fmax
CLKBA or CLKAB
tpd
d
A or B
A or B
B or A
SBA or SAB†
A or B
ten
OE
A or B
tdis
di
OE
A or B
ten
DIR
A or B
tdis
di
DIR
A or B
tt
Any
VCC
MIN
TA = 25°C
TYP
MAX
SN54HCT646
MIN
MAX
SN74HCT646
MIN
4.5 V
31
54
22
27
5.5 V
36
64
24
29
MAX
UNIT
MHz
4.5 V
18
36
54
45
5.5 V
16
32
49
41
4.5 V
14
27
41
34
5.5 V
12
24
37
31
4.5 V
20
38
57
48
5.5 V
17
34
51
43
4.5 V
25
49
74
61
5.5 V
22
44
67
55
4.5 V
25
49
74
61
5.5 V
22
44
67
55
4.5 V
25
49
74
61
5.5 V
22
44
67
55
4.5 V
25
49
74
61
5.5 V
22
44
67
55
4.5 V
9
12
18
15
5.5 V
7
11
16
14
ns
ns
ns
ns
ns
ns
† These parameters are measured with the internal output state of the storage register opposite that of the bus input.
switching characteristics over recommended operating free-air temperature range, CL = 150 pF
(unless otherwise noted) (see Figure 2)
PARAMETER
tpd
d
FROM
(INPUT)
TO
(OUTPUT)
CLKBA or CLKAB
A or B
A or B
B or A
SBA or SAB†
A or B
OE
A or B
DIR
A or B
ten
tt
Any
VCC
MIN
TA = 25°C
TYP
MAX
SN54HCT646
MIN
MAX
SN74HCT646
MIN
MAX
4.5 V
24
53
80
66
5.5 V
22
47
52
60
4.5 V
22
44
67
55
5.5 V
20
39
60
50
4.5 V
26
55
83
69
5.5 V
24
49
74
62
4.5 V
33
66
100
87
5.5 V
22
59
90
74
4.5 V
33
66
100
87
5.5 V
22
59
90
74
4.5 V
17
42
63
53
5.5 V
14
38
57
48
UNIT
ns
ns
ns
† These parameters are measured with the internal output state of the storage register opposite that of the bus input.
operating characteristics, TA = 25°C
PARAMETER
Cpd
TEST CONDITIONS
Power dissipation capacitance
No load
PRODUCT PREVIEW information concerns products in the formative or
design phase of development. Characteristic data and other
specifications are design goals. Texas Instruments reserves the right to
change or discontinue these products without notice.
6
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TYP
50
UNIT
pF
SN54HCT646, SN74HCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCLS178B – MARCH 1984 – REVISED MAY 1997
PARAMETER MEASUREMENT INFORMATION
VCC
S1
Test
Point
From Output
Under Test
PARAMETER
ten
RL
tdis
CL
(see Note A)
S2
tPZH
RL
1 kΩ
tPZL
tPHZ
1 kΩ
CL
S1
S2
50 pF
or
150 pF
Open
Closed
Closed
Open
Open
Closed
Closed
Open
Open
Open
50 pF
tPLZ
50 pF
or
150 pF
––
tpd or tt
LOAD CIRCUIT
3V
High-Level
Pulse
1.3 V
3V
Reference
Input
1.3 V
0V
1.3 V
tsu
0V
tw
Data
Input 1.3 V
0.3 V
3V
Low-Level
Pulse
1.3 V
1.3 V
Output
Control
(Low-Level
Enabling)
3V
1.3 V
0V
tPLH
In-Phase
Output
1.3 V
10%
tPHL
90%
90%
tr
Out-ofPhase
Output
tPHL
90%
VOH
1.3 V
10% V
OL
tf
1.3 V
10%
tf
3V
1.3 V
0.3 V 0 V
tf
3V
1.3 V
1.3 V
0V
tPZL
Output
Waveform 1
(See Note B)
tPLZ
≈ VCC
1.3 V
10%
VOL
tPZH
tPLH
1.3 V
10%
2.7 V
VOLTAGE WAVEFORMS
SETUP AND HOLD AND INPUT RISE AND FALL TIMES
VOLTAGE WAVEFORMS
PULSE DURATIONS
1.3 V
2.7 V
tr
0V
Input
th
90%
VOH
VOL
tr
VOLTAGE WAVEFORMS
PROPAGATION DELAY AND OUTPUT RISE AND FALL TIMES
Output
Waveform 2
(See Note B)
1.3 V
90%
VOH
≈0V
tPHZ
VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES FOR 3-STATE OUTPUTS
NOTES: A. CL includes probe and test-fixture capacitance.
B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control.
Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control.
C. Phase relationships between waveforms were chosen arbitrarily. All input pulses are supplied by generators having the following
characteristics: PRR ≤ 1 MHz, ZO = 50 Ω, tr = 6 ns, tf = 6 ns.
D. For clock inputs, fmax is measured when the input duty cycle is 50%.
E. The outputs are measured one at a time with one input transition per measurement.
F. tPLZ and tPHZ are the same as tdis.
G. tPZL and tPZH are the same as ten.
H. tPLH and tPHL are the same as tpd.
Figure 2. Load Circuit and Voltage Waveforms
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pertaining to warranty, patent infringement, and limitation of liability.
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accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
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Copyright  1998, Texas Instruments Incorporated