DM9370 7-Segment Decoder/Driver/Latch with Open-Collector Outputs
October 1988
Revised March 2000
DM9370
7-Segment Decoder/Driver/Latch
with Open-Collector Outputs
General Description
The DM9370 is a 7-segment decoder driver incorporating
input latches and output circuits to directly drive incandes-
cent displays. It can also be used to drive common anode
LED displays in either a multiplexed mode or directly with
the aid of external current limiting resistors.
Ordering Code:
Order Number
DM9370
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
A0–A3
LE
RBI
RBO
a–g
Description
Address Inputs
Latch Enable Input (Active LOW)
Ripple Blanking Input (Active LOW)
Ripple Blanking as Output (Active LOW)
as Input (Active LOW)
Segment Outputs (Active LOW)
© 2000 Fairchild Semiconductor Corporation
DS009797
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DM9370
Truth Table
*The RBI will blank the display only if binary zero is stored in the latches.
**RBO used as an input overdrives all other input conditions.
H
=
HIGH Voltage Level
L
=
LOW Voltage Level
X
=
Immaterial
Functional Description
The DM9370 has active LOW outputs capable of sinking in
excess of 25 mA which allows it to drive a wide variety of 7-
segment incandescent displays directly. It may also be
used to drive common anode LED displays, multiplexed or
directly with the aid of suitable current limiting resistors.
This device accepts a 4-bit binary code and produces out-
put drive to the appropriate segments of the 7-segment dis-
play. It has a hexadecimal decode format which produces
numeric codes “0” through “9” and alpha codes “A” through
“F” using upper 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 DM9370 at normal
TTL speeds. This feature means that data can be routed
directly from high speed counters and frequency dividers
into the display without slowing down the system clock or
providing intermediate data storage.
The latch/decoder combination is a simple system which
drives incandescent displays with multiplexed data inputs
from MOS time clocks, DVMs, calculator chips, etc. Data
inputs are multiplexed while the displays are in static mode.
This lowers component and insertion costs since several
circuits—seven diodes per display, strobe drivers, a sepa-
rate display voltage source, and clock failure detect cir-
cuits—traditionally found in incandescent multiplexed
display systems are eliminated. It also allows low strobing
rates to be used without display flicker.
Another DM9370 feature is the reduced loading on the
data inputs when the Latch Enable is HIGH (only 10
µA
typ). This allows many DM9370s to be driven from a MOS
device in multiplex mode without the need for drivers on
the data lines. The DM9370 also provides automatic blank-
ing of the leading and/or trailing-edge zeroes in a multidigit
decimal number, resulting in an easily readable decimal
display conforming to normal writing practice. In an 8-digit
mixed integer fraction decimal representation, using the
automatic blanking capability, 0060.0300 would be dis-
played 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 significant decoder stage
should have the RBI input grounded; and since suppres-
sion 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 fractional part of a
display will provide automatic suppression of trailing-edge
zeroes. The RBO terminal of the decoder can be OR-tied
with a modulating signal via an isolating buffer to achieve
pulse duration intensity modulation. A suitable signal can
be generated for this purpose by forming a variable fre-
quency multivibrator with a cross coupled pair of TTL or
DTL gates.
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2
DM9370
Absolute Maximum Ratings
(Note 1)
Supply Voltage
Input Voltage
Operating Free Air Temperature Range
Storage Temperature Range
7V
5.5V
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
W
(L)
Supply Voltage
HIGH Level Input Voltage
LOW Level Input Voltage
HIGH Level Output Current
LOW Level Output Current
Free Air Operating Temperature
Setup Time HIGH or LOW
A
n
to LE
Hold Time HIGH or LOW
A
n
to LE
LE Pulse Width LOW
0
Parameter
Min
4.75
2
0.8
−80
3.2
70
30
20
0
0
45
Nom
5
Max
5.25
Units
V
V
V
µA
mA
°C
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
IL
I
OS
V
OH
V
OL
Parameter
Input Clamp Voltage
HIGH Level
Output Voltage
LOW Level
Output Voltage
Input Current @ Max Input Voltage
LOW Level Input Current
Short Circuit Output Current
Output HIGH Voltage
Output LOW Voltage
RBO
RBO
a–g
I
OH
I
CC
Output HIGH Current, a–g
Power Supply Current
V
CC
=
Max
A
1
, A
2
, A
3
, LE
=
GND
V
CC
=
Max, Outputs OPEN
A
0
, A
1
, A
2
, LE
=
GND
V
CC
=
Max, Outputs OPEN
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.
Conditions
V
CC
=
Min, I
I
= −12
mA
V
CC
=
Min, I
OH
=
Max
V
IL
=
Max
V
CC
=
Min, I
OL
=
Max
V
IH
=
Min
V
CC
=
Max, V
I
=
5.5V
V
CC
=
Max, V
I
=
0.4V
V
CC
=
Max (Note 3)
V
CC
=
Min, I
OH
−80 µA
I
OL
=
3.2 mA
I
OL
=
25 mA
V
CC
=
Min
Min
Typ
(Note 2)
Max
−1.5
Units
V
V
2.4
3.4
0.2
0.4
1
−1.6
V
mA
mA
mA
V
−20
2.4
−70
0.4
V
0.4
250
105
105
mA
94
µA
µA
Switching Characteristics
V
CC
= +
5.0V, T
A
= +25°C
Symbol
t
PLH
t
PHL
t
PLH
t
PHL
Propagation Delay
A
n
to a–g
Propagation Delay
LE to a–g
Parameter
C
L
=
15 PF, R
L
=
500Ω
Min
Max
75
50
90
70
Units
ns
ns
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4
DM9370 7-Segment Decoder/Driver/Latch with Open-Collector Outputs
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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SEMICONDUCTOR CORPORATION. As used herein:
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5
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