DM9368
7-Segment Decoder/Driver/Latch with Constant Current
Source Outputs
General Description
The DM9368 is a 7-segment decoder driver incorporating in-
put latches and constant current output circuits to drive com-
mon cathode type LED displays directly.
Connection Diagram
Pin Name Description
A0–A3 Address (Data) Inputs
RBO Ripple Blanking Output (Active Low)
RBI Ripple Blanking Input (Active Low)
a–g Segment Drivers-Outputs
LE Latch Enable Input (Active Low)
Dual-In-Line Package
DS009796-1
Order Number DM9368N
See Package Number N16E
March 1998
DM9368 7-Segment Decoder/Driver/Latch with Constant Current Source Outputs
© 1998 Fairchild Semiconductor Corporation DS009796 www.fairchildsemi.com
Absolute Maximum Ratings (Note 1)
Supply Voltage 7V
Input Voltage 5.5V
Operating Free Air Temperature
Range 0˚C to +70˚C
Storage Temperature Range −65˚C to +150˚C
Recommended Operating Conditions
Symbol Parameter DM9368 Units
Min Nom Max
V
CC
Supply Voltage 4.75 5 5.25 V
V
IH
High Level Input Voltage 2 V
V
IL
Low Level Input Voltage 0.8 V
I
OH
High Level Output Current −80 µA
I
OL
Low Level Output Current RBO 3.2 mA
T
A
Free Air Operating Temperature 0 70 ˚C
t
s
(H) Setup Time High 30 ns
A
n
to LE
t
h
(H) Hold Time HIGH 0 ns
A
n
to LE
t
s
(L) Setup Time LOW 20 ns
A
n
to LE
t
h
(L) Hold Time LOW 0 ns
A
n
to LE
t
w
(L) LE Pulse Width LOW 45 ns
I
OH
Segment Output HIGH Current −16 −22 mA
I
OL
Segment Output LOW Current −250 250 µA
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” table are not guaranteed at the absolute maximum ratings. The “Recommended Operating
Conditions” table will define the conditions for actual device operation.
Electrical Characteristics
Over recommended operating free air temperature range (unless otherwise noted)
Symbol Parameter Conditions Min Typ Max Units
(Note 1)
V
I
Input Clamp Voltage V
CC
=Min, I
I
=−12 mA −1.5 V
V
OH
High Level V
CC
=Min, I
OH
=Max, 2.4 3.4 V
Output Voltage V
IL
=Max
V
OL
Low Level V
CC
=Min, I
OL
=Max, 0.2 0.4 V
Output Voltage V
IH
=Min
I
I
Input Current @Max V
CC
=Max, V
I
=5.5V 1 mA
Input Voltage
I
IH
High Level Input Current V
CC
=Max, V
I
=2.4V 40 µA
I
IL
Low Level Input Current V
CC
=Max, V
I
=0.4V −1.6 mA
I
OS
Short Circuit V
CC
=Max −18 −57 mA
Output Current (Note 2)
I
CC
Supply Current V
CC
=Max, Outputs Open, 67 mA
Data & Latch Inputs =0V
Note 2: All typicals are at VCC =5V, TA=25˚C.
Note 3: Not more than one output should be shorted at a time.
www.fairchildsemi.com 2
Switching Characteristics
V
CC
=5.0V, T
A
=25˚C (See Section 1 for Waveforms and Load Configuations)
C
L
=15 pF
Symbol Parameter R
L
=100ΩUnits
Min Max
t
PLH
Propagation Delay 50 ns
t
PHL
A
n
to a–g 75
t
PLH
Propagation Delay 70 ns
t
PHL
LE to a–g 90
Functional Description
The ’68 is a 7-segment decoder driver designed to drive
7-segment common cathode LED displays. The ’68 drives
any common cathode LED display rated at a nominal 20 mA
at 1.7V per segment without need for current limiting resis-
tors.
This device accepts a 4-bit binary code and produces output
drive to the appropriate segments of the 7-segment display.
It has a hexadecimal decode format which produces numeric
codes “0” thru “9” and alpha codes “A” through “F” using up-
per and lower case fonts.
Latches on the four data inputs are controlled by an active
LOW latch enable LE. When the LE is LOW, the state of the
outputs is determined by the input data. When the LE goes
HIGH, the last data present at the inputs is stored in the
latches and the outputs remain stable. The LE pulse width
necessary to accept and store data is typically 30 ns which
allows data to be strobed into the ’68 at normal TTL speeds.
This feature means that data can be routed directly from high
speed counters and frequency dividers into the display with-
out slowing down the system clock or providing intermediate
data storage.
Another feature of the ’68 is that the unit loading on the data
inputs is very low (−100 µA Max) when the latch enable is
HIGH. This allows ’68s to be driven from an MOS device in
multiplex mode without the need for drivers on the data lines.
The ’68 also has provision for automatic blanking of the lead-
ing and/or trailing edge zeros in a multidigit decimal number,
resulting in an easily readable decimal display conforming to
normal writing practice. In an eight digit mixed integer frac-
tion decimal representation, using the automatic blanking ca-
pability, 0060.0300 would be displayed as 60.03. Leading
edge zero suppression is obtained by connecting the Ripple
Blanking Output (RBO) of a decoder to the Ripple Blanking
Input (RBI) of the next lower stage device. The most signifi-
cant decoder stage should have the RBI input grounded; and
since suppression of the least significant integer zero in a
number is not usually desired, the RBI input of this decoder
stage should be left open. A similar procedure for the frac-
tional part of a display will provide automatic suppression of
trailing edge zeros. The RBO terminal of the decoder can be
OR-tied with a modulating signal via an isolating buffer to
achieve pulse duration intensity modulation.Asuitable signal
can be generated for this purpose by forming a variable fre-
quency multivibrator with a cross coupled pair of TTL or DTL
gates.
Logic Symbol
DS009796-2
VCC =Pin 16
GND =PIN 8
3 www.fairchildsemi.com
Truth Table
Logic Diagram
DS009796-8
DS009796-4
*The RBI will blank the display only if a binary zero is stored in the latches.
*The RBO used as an input overrides all other input conditions.
H=HIGH Voltage Level
L=LOW Voltage Level
X=Immaterial
DS009796-3
www.fairchildsemi.com 4
Numerical Designations
Parallel Data Display System with Ripply Blanking
DS009796-5
Common Cathode LED Display
DS009796-6
5 www.fairchildsemi.com
Display Demultiplexing System with Ripple Blanking
Common Cathode LED Display
DS009796-7
Note: Digit address data must be non-overlapping. Standard TTL decoders like the 9301, 9311, 7442 or 74155 must be strobed, since the address decoding
glitches could cause erroneous data to be strobed into the latches.
www.fairchildsemi.com 6
7
Physical Dimensions inches (millimeters) unless otherwise noted
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DE-
VICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMI-
CONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or sys-
tems which, (a) are intended for surgical implant into
the body, or (b) support or sustain life, and (c) whose
failure to perform when properly used in accordance
with instructions for use provided in the labeling, can
be reasonably expected to result in a significant injury
to the user.
2. A critical component in any component of a life support
device or system whose failure to perform can be rea-
sonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
Fairchild Semiconductor
Corporation
Americas
Customer Response Center
Tel: 1-888-522-5372
www.fairchildsemi.com
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Europe Fax: +49 (0) 1 80-530 85 86
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Tel: 81-3-5620-6175
Fax: 81-3-5620-6179
16-Lead Molded Dual-In-Line Package (N)
Order Number DM9368N
Package Number N16E
DM9368 7-Segment Decoder/Driver/Latch with Constant Current Source Outputs
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.
