TL/F/9797
DM9370 7-Segment Decoder/Driver/Latch with Open-Collector Outputs
June 1989
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.
Connection Diagram
Dual-in-Line Package
TL/F/9797–1
Order Number DM9370N
See NS Package Number N16E
Pin Names Description
A0– A3 Address Inputs
LE Latch Enable Input (Active LOW)
RBI Ripple Blanking Input (Active LOW)
RBO Ripple Blanking as Output (Active LOW)
as Input (Active LOW)
a–g Segment Outputs (Active LOW)
C1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.
Absolute Maximum Ratings (Note)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage 7V
Input Voltage 5.5V
Operating Free Air Temperature Range
Commercial 0§Ctoa
70§C
Storage Temperature Range b65§Ctoa
150§C
Note:
The ‘‘Absolute Maximum Ratings’’ are those values
beyond which the safety of the device cannot be guaran-
teed. The devic 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.
Recommended Operating Conditions
Symbol Parameter DM9370 Units
Min Nom Max
VCC Supply Voltage 4.75 5 5.25 V
VIH High Level Input Voltage 2 V
VIL Low Level Input Voltage 0.8 V
IOH High Level Output Current b80 mA
IOL Low Level Output Current 3.2 mA
TAFree Air Operating Temperature 0 70 §C
ts(H) Setup Time HIGH or LOW 30 ns
ts(L) Anto LE 20
th(H) Hold Time HIGH or LOW 0 ns
th(L) Anto LE 0
tw(L) LE Pulse Width LOW 45 ns
Electrical Characteristics
Over recommended operating free air temperature range (unless otherwise noted)
Symbol Parameter Conditions Min Typ Max Units
(Note 1)
VIInput Clamp Voltage VCC eMin, IIeb
12 mA b1.5 V
VOH High Level Output VCC eMin, IOH eMax 2.4 3.4 V
Voltage VIL eMax
VOL Low Level Output VCC eMin, IOL eMax 0.2 0.4 V
Voltage VIH eMin
IIInput Current @Max VCC eMax, VIe5.5V 1mA
Input Voltage
IIH High Level Input Current VCC eMax, VIe2.4V 40 mA
IIL Low Level Input Current VCC eMax, VIe0.4V b1.6 mA
IOS Short Circuit VCC eMax DM74 b20 b70 mA
Output Current (Note 2)
VOH Output HIGH Voltage RBO VCC eMin, IOH b80 mA 2.4 V
VOL Output LOW Voltage RBO IOL e3.2 mA VCC eMin 0.4 V
a–g IOL e25 mA 0.4
IOH Output HIGH Current, a–g 250 mA
ICC Power Supply Current VCC eMax 105 mA
A1,A
2
,A
3
,LEeGND 105
VCC eMax, Outputs Open mA
A0,A
1
,A
2
,LEeGND 94
VCC eMax, Outputs Open
2
Switching Characteristics
VCC ea
5.0V, TAea
25§C (See Section 1 for waveforms and load configurations)
CLe15 PF
Symbol Parameter RLe500XUnits
Min Max
tPLH Propagation Delay 75 ns
tPHL Anto a–g 50
tPLH Propagation Delay 90 ns
tPHL LE to a–g 70
Functional Description
The ’70 has active LOW outputs capable of sinking in ex-
cess 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 output
drive to the appropriate segments of the 7-segment display.
It has a hexadecimal decode format which produces numer-
ic 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 ’70 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 interme-
diate 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
circuitsÐseven diodes per display, strobe drivers, a sepa-
rate display voltage source, and clock failure detect cir-
cuitsÐtraditionally found in incandescent multiplexed dis-
play systems are eliminated. It also allows low strobing rates
to be used without display flicker.
Another ’70 feature is the reduced loading on the data in-
puts when the Latch Enable is HIGH (only 10 mA typ). This
allows many ’70s to be driven from a MOS device in multi-
plex mode without the need for drivers on the data lines.
The ’70 also provides automatic blanking 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 capa-
bility, 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 decod-
er stage should be left open. A similar procedure for the
fractional part of a display will provide automatic suppres-
sion of trailing-edge zeroes. The RBO terminal of the decod-
er can be OR-tied with a modulating signal via an isolating
buffer to achieve pulse duration intensity modulation. A suit-
able signal can be generated for this purpose by forming a
variable frequency multivibrator with a cross coupled pair of
TTL or DTL gates.
Logic Symbol
TL/F/9797–2
VCC ePin 16
GND ePin 8
3
Truth Table
TL/F/9797–6
TL/F/9797–4
*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.
HeHIGH Voltage Level
LeLOW Voltage Level
XeImmaterial
Numerical Designation
TL/F/9797–5
4
Logic Diagram
TL/F/9797–3
5
DM9370 7-Segment Decoder/Driver/Latch with Open-Collector Outputs
Physical Dimensions inches (millimeters)
16-Lead Molded Dual-In-Line Package (N)
Order Number DM9370N
NS Package Number N16E
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failure to perform, when properly used in accordance support device or system, or to affect its safety or
with instructions for use provided in the labeling, can effectiveness.
be reasonably expected to result in a significant injury
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