
4-241
FAST AND LS TTL DATA
Product Preview
OCTAL TRANSCEIVER/REGISTER 
WITH 3-STATE OUTPUTS
These devices consist of bus transceiver circuits with 3-state 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 will be clocked into the registers as the appropriate clock pin goes to a 
high logic level. Output Enable (OE
) and DIR pins are provided to control the 
transceiver function. In the transceiver mode, data present at the high 
impedance port may be stored in either the A or the B register or in both. The 
select controls can multiplex stored and real-time (transparent mode) data. 
The direction control determines which bus will receive data when the enable 
OE
 is Active LOW. In the isolation mode (OE HIGH), A data may be stored
in the B register and/or B data may be stored in the A register.
• Independent Registers for A and B
• Multiplexed Real-Time and Stored Data
• Choice of True (F646) and Inverting (F648) Data Paths
• 3-State Outputs
PIN ASSIGNMENTS
22 21 20 19 18 17
1 2 3 4 5 6
7
24 23
8
V
CC
CPAB
CPBA SBA OE
B
0
B
2
B
1
B
3
SAB DIR A0A1A2A3A
4
9 10
11
12
A5A6A7GND
16 15 14 13
B
4
B
6
B
5
B
7
F646
22 21 20 19 18 17
1 2 3 4 5 6
7
24 23
8
V
CC
CPAB
CPBA SBA OE
B
0
B
2
B
1
B
3
SAB DIR A
0A1A2A3A4
9 10
11
12
A
5A6A7
GND
16 15 14 13
B
4
B
6
B
5
B
7
F648
A0A1A2A3A4A5A6A
7
B0B1B2B3B4B5B6B
7
 F646
CPAB 
SAB 
DIR 
CPBA 
SBA 
OE
A0A1A2A3A4A5A6A
7
B0B1B2B3B4B5B6B
7
F648
CPAB 
SAB 
DIR 
CPBA 
SBA 
OE
LOGIC SYMBOLS
1 
2
3 
23 
22 
21
20 19 18 17 16 15 14 13
4 5 6 7 8 9 10 11
20 19 18 17 16 15 14 13
1 
2
3 
23 
22 
21
4 5 6 7 8 9 10 11
This document contains information on a product under development. Motorola reserves the right to change or discontinue this product without notice.
MC54/74F646
MC54/74F648
OCTAL TRANSCEIVER/REGISTER
WITH 3-STATE OUTPUTS
FAST SCHOTTKY TTL
ORDERING INFORMATION
MC54FXXXJ Ceramic 
MC74FXXXN Plastic 
MC74FXXXDW SOIC
N SUFFIX
PLASTIC
CASE 724-03
DW SUFFIX
SOIC
CASE 751E-03
24
1
24
1
J SUFFIX
CERAMIC
CASE 758-01
24
1

4-242
FAST AND LS TTL DATA
MC54/74F646 • MC54/74F648
FUNCTION TABLE
Inputs Data I/O*
OE bar DIR CPAB CPBA SAB SBA A0–A
7
B0–B
7
H 
H 
H 
H
X 
X 
X 
X
H or L
↑
X
↑
H or L
X
↑ 
↑
X 
X 
X 
X
X 
X 
X 
X
Input 
Input 
Input 
Input
Input 
Input 
Input 
Input
Isolation 
Store An Data in A Register 
Store Bn Data in B Register 
Store An/Bn Data in A/B Register
L 
L 
L 
L
H 
H 
H 
H
X
↑
H or L
↑
X 
X 
X 
X
L
L 
H 
H
X 
X 
X 
X
Input 
Input 
Input 
Input
Output 
Output 
Output 
Output
An to Bn — Real Time (Transparent Mode) 
Store An Data in A Register 
A Register to Bn (Stored Mode) 
Clock An Data to Bn and into A Register
L 
L 
L 
L
L 
L 
L 
L
X 
X 
X 
X
X
↑
H or L
↑
X
X
X
X
L 
L 
H 
H
Output 
Output 
Output 
Output
Input 
Input 
Input 
Input
Bn to An — Real Time (Transparent Mode) 
Store Bn Data in B Register 
B Register to An (Stored Mode) 
Clock An Data to Bn and into B Register
*The data output function may be enabled or disabled by various signals at the OE bar and DIR inputs. Data input functions are always enabled; i.e., data at the
*bus pins will be stored on every low-to-high transition of the appropriate clock inputs.
H = HIGH voltage level 
L = LOW voltage level 
X = Don’t Care 
↑ = Low-to-High transition
GUARANTEED OPERATING RANGES
Symbol Parameter Min Typ Max Unit
V
CC
DC Supply Voltage 54, 74 4.5 5.0 5.5 V
T
A
Operating Ambient Temperature Range
54 
74
–55
0
25 
25
125
70
°C
I
OH
Output Current  High
54 
74
— 
—
— 
—
–12 
–15
mA
I
OL
Output Current  Low
54 
74
— 
—
— 
—
48 
64
mA

4-243
FAST AND LS TTL DATA
MC54/74F646 • MC54/74F648
TO 7 OTHER CHANNELS
A
0
B
0
OE
DIR
CPBA
SBA
CPAB
SAB
D
0
C
0
D
0
C
0
1 OF 8 CHANNELS
LOGIC DIAGRAM
F646

4-244
FAST AND LS TTL DATA
MC54/74F646 • MC54/74F648
TO 7 OTHER CHANNELS
A
0
B
0
OE
DIR
CPBA
SBA
CPAB
SAB
D
0
C
0
D
0
C
0
1 OF 8 CHANNELS
LOGIC DIAGRAM
F648

4-245
FAST AND LS TTL DATA
MC54/74F646 • MC54/74F648
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits
Symbol Parameter Min Typ Max Unit
V
IH
Input HIGH Voltage 2.0 — — V Guaranteed as a HIGH Signal
V
IL
Input LOW Voltage — — 0.8 V Guaranteed as a LOW Signal
V
IK
Input Clamp Diode Voltage — — –1.2 V VCC = MIN, IIN = –18 mA
54/74 2.4 — — V IOH = –3.0 mA VCC = 4.5 V
74 2.7 — — V IOH = –3.0 mA VCC = 4.75 V
54 2.0 — — V IOH = –12.0 mA VCC = 4.5 V 
74 2.0 — — V IOH = –15.0 mA VCC = 4.5 V 
54 — — 0.55 V IOL = 48 mA VCC = MIN
74 — — 0.55 V IOL = 64 mA VCC = MIN
Non I/O Pins — — 20 µA VCC = MAX, VIN = 2.7 V
Non I/O Pins — — 100 µA VCC = MAX, VIN = 7.0 V
I/O (Aa, Bn) — — 1.0 mA VCC = MAX, VIN = 5.5 V
I
IL
Input LOW Current Non I/O Pins — — –600 µA VCC = MAX, VIN = 0.5 V
IIH + I
OZH
Output Leakage Current I/O (An, Bn) — — 70 µA VCC = MAX V
OUT
 = 2.7 V
IIL + I
OZL
Output Leakage Current I/O (An, Bn) — — –650 µA VCC = MAX, V
OUT
 = 0.5 V
I
OS
Output Short Circuit Current (Note 2) –100 — –225 mA VCC = MAX, V
OUT
 = GND
I
CCH
— — 135 V
out
 = HIGH
I
CC
Power Supply Current
I
CCL
— — 150 mA V
out
 = LOW VCC = MAX
I
CCZ
— — 150 V
out
 = HIGH Z
NOTES:
1. For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions for the applicable device type.
2. Not more than one output should be shorted at a time, nor for more than 1 second.

4-246
FAST AND LS TTL DATA
MC54/74F646 • MC54/74F648
AC ELECTRICAL CHARACTERISTICS
54/74F 54F 74F
TA = +25°C
VCC = +5.0 V
CL = 50 pF 
RL = 500 Ω
TA = –55°C to +125°C
VCC = +5.0 V ±10%
CL = 50 pF 
RL = 500 Ω
TA = 0°C to +70°C
VCC = +5.0 V ±10%
CL = 50 pF 
RL = 500 Ω
Symbol Parameter Min Max Min Max Min Max Unit
f
MAX
Maximum Clock Frequency 100 — 75 — 90 — MHz
t
PLH
t
PHL
Propagation Delay 
Clock to Bus
2.0
2.0
7.0
8.0
2.0
2.0
8.5
9.5
2.0
2.0
8.0
9.0
ns
t
PLH
t
PHL
Propagation Delay 
Bus to Bus (F646)
1.0
1.0
7.0
6.5
1.0
1.0
8.0
8.0
1.0
1.0
7.5
7.0
ns
t
PLH
t
PHL
Propagation Delay 
Bus to Bus (F648)
1.0
1.0
7.0
6.5
1.0
1.0
10.0
9.0
1.0
1.0
7.5
7.0
ns
t
PLH
t
PHL
Propagation Delay 
SBA or SAB to An or B
n
2.0
2.0
7.5
7.5
2.0
2.0
10.0
10.0
2.0
2.0
9.0
9.0
ns
t
PZH
t
PZL
Output Enable Time 
OE
 to An or B
n
2.0
2.0
7.0
7.0
2.0
2.0
9.5
9.5
2.0
2.0
8.5
8.5
ns
t
PHZ
t
PLZ
Output Disable Time 
OE
 to An or B
n
1.0
2.0
7.0
7.0
1.0
2.0
9.5
9.5
1.0
2.0
8.5
8.5
ns
t
PZH
t
PZL
Output Enable Time 
DIR to An or B
n
2.0
2.0
7.0
7.0
2.0
2.0
9.5
9.5
2.0
2.0
8.5
8.5
ns
t
PHZ
t
PLZ
Output Disable Time 
DIR to An or B
n
1.0
2.0
7.0
7.0
1.0
2.0
9.5
9.5
1.0
2.0
8.5
8.5
ns
AC OPERATING REQUIREMENTS
54/74F 54F 74F
TA = +25°C
VCC = +5.0 V
CL = 50 pF 
RL = 500 Ω
TA = –55°C to +125°C
VCC = +5.0 V ±10%
CL = 50 pF 
RL = 500 Ω
TA = 0°C to +70°C
VCC = +5.0 V ±10%
CL = 50 pF 
RL = 500 Ω
Symbol Parameter Min Max Min Max Min Max Unit
t
s(H)
t
s(L)
Setup Time, HIGH or LOW 
Bus to Clock
4.0
4.0
— 
—
5.0
5.0
— 
—
5.0
5.0
— 
—
ns
t
h(H)
t
h(L)
Hold Time, HIGH or LOW 
Bus to Clock
0.0
0.0
— 
—
0.0
0.0
— 
—
0.0
0.0
— 
—
ns
t
w(H)
t
w(L)
Clock Pulse Width 
HIGH or LOW
4.0
5.0
— 
—
4.0
5.0
— 
—
4.0
5.0
— 
—
ns