DM74LS503 8-Bit Successive Approximation Register
March 1989
Revised March 2000
DM74LS503
8-Bit Successive Approximation Register
(with Expansion Control)
General Description
The DM74LS503 register has an active LOW Enable (E)
input that is used in cascading two or more packages for
longer word lengths. A HIGH signal on E, after a START
operation, forces Q7 HIGH and prevents the device from
accepting serial data. With the E input of an DM74LS503
connected to the CC output of a preceding (more signifi-
cant) device, the DM74LS503 will be inhibited until the pre-
ceding device is filled, causing its CC output to go LOW.
This LOW signal then enables the DM74LS503 to accept
the serial data on subsequent clocks.
Features
s
Performs serial-to-parallel conversion
s
Expansion control for longer words
s
Storage and control for successive approximation A to D
conversion
s
Low power Schottky version of 2503
Ordering Code:
Order Number
DM74LS503N
Package Number
N16E
Package Description
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Connection Diagram
Logic Symbol
V
CC
=
Pin 16
GND
=
Pin 8
Pin Descriptions
Pin Names
D
S
CP
E
CC
Q0–Q7
Q7
Description
Serial Data Input
Start Input (Active LOW)
Clock Pulse Input (Active Rising Edge)
Conversion Enable Input (Active LOW)
Conversion Complete Output (Active LOW)
Parallel Register Outputs
Complement of Q7 Output
© 2000 Fairchild Semiconductor Corporation
DS010190
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DM74LS503
Logic Diagrams
Note:
Cell logic is repeated for register stages Q5 to Q1.
Connection for Longer Word Lengths
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DM74LS503
Absolute Maximum Ratings
(Note 1)
Supply Voltage
Input Voltage
Operating Free Air Temperature Range
Storage Temperature Range
7V
7V
0°C to
+70°C
−65°C
to
+150°C
Note 1:
The “Absolute Maximum Ratings” are those values beyond which
the safety of the device cannot be guaranteed. The device should not be
operated at these limits. The parametric values defined in the Electrical
Characteristics tables are not guaranteed at the absolute maximum ratings.
The “Recommended Operating Conditions” table will define the conditions
for actual device operation.
Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
I
OH
I
OL
T
A
t
S
(H)
t
S
(L)
t
H
(H)
t
H
(L)
t
S
(H)
t
S
(L)
t
H
(H)
t
H
(L)
t
W
(H)
t
W
(L)
Supply Voltage
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Voltage
LOW Level Output Current
Free Air Operating Temperature
Setup Time HIGH or LOW
S to CP
Hold Time HIGH or LOW
S to CP
Setup Time HIGH or LOW
D to CP
Hold Time HIGH or LOW
D to CP
CP Pulse Width HIGH or LOW
0
16
16
0
0
8
8
10
10
46
46
Parameter
Min
4.75
2
0.8
−0.4
8
70
Nom
5
Max
5.25
Units
V
V
V
mA
mA
°C
ns
ns
ns
ns
ns
Electrical Characteristics
Over recommended operating free air temperature range (unless otherwise noted)
Symbol
V
I
V
OH
V
OL
I
I
I
IH
I
IL
I
OS
I
CC
Parameter
Input Clamp Voltage
HIGH Level
Output Voltage
LOW Level
Output Voltage
Input Current @ Max
Input Voltage
HIGH Level Input Current
LOW Level Input Current
Short Circuit Output Current
Supply Current
Conditions
V
CC
=
Min, I
I
= −18
mA
V
CC
=
Min, I
OH
=
Max,
V
IL
=
Max
V
CC
=
Min, I
OL
=
Max, V
IH
=
Min
I
OL
=
4 mA, V
CC
=
Min
V
CC
=
Max, V
I
=
7V
V
I
=
10V
V
CC
=
Max, V
I
=
2.7V
V
CC
=
Max, V
I
=
0.4V
V
CC
=
Max (Note 3)
V
CC
=
Max
−20
2.7
0.5
0.4
0.1
20
−0.8
−100
65
Min
Typ
(Note 2)
Max
−1.5
Units
V
V
V
mA
µA
mA
mA
mA
Note 2:
All typicals are at V
CC
=
5V, T
A
=
25°C.
Note 3:
Not more than one output should be shorted at a time, and the duration should not exceed one second.
Switching Characteristics
V
CC
= +
5.0V, T
A
= +25°C
Symbol
f
MAX
t
PLH
t
PHL
t
PLH
t
PHL
Parameter
Maximum Count Frequency
Propagation Delay
CP to Qn or CC
Propagation Delay
E to Q7
R
L
=
2 kΩ, C
L
=
15 pF
Min
15
35
25
20
24
Max
Units
MHz
ns
ns
3
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DM74LS503 8-Bit Successive Approximation Register
Physical Dimensions
inches (millimeters) unless otherwise noted
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Package Number N16E
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and
Fairchild reserves the right at any time without notice to change said circuitry and specifications.
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