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DM9368 7-Segment Decoder/Driver/Latch with Constant Current Source Outputs
October 1988 Revised December 2001
DM9368 7-Segment Decoder/Driver/Latch with Constant Current Source Outputs
General Description
The DM9368 is a 7-segment decoder driver incorporating input latches and constant current output circuits to drive common cathode type LED displays directly.
Ordering Code:
Order Number DM9368N Package Number N16E Package Description 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Connection Diagram
Logic Symbol
VCC = Pin 16 GND = PIN 8
Pin Descriptions
Pin Name A0-A3 RBO RBI a-g LE Description Address (Data) Inputs Ripple Blanking Output (Active LOW) Ripple Blanking Input (Active LOW) Segment Drivers-Outputs Latch Enable Input (Active LOW)
(c) 2001 Fairchild Semiconductor Corporation
DS009796
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DM9368
Truth Table
*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
Functional Description
The DM9368 is a 7-segment decoder driver designed to drive 7-segment common cathode LED displays. The DM9368 drives any common cathode LED display rated at a nominal 20 mA at 1.7V per segment without need for 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 numeric codes "0" thru "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 DM9368 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. Another feature of the DM9368 is that the unit loading on the data inputs is very low (-100 A Max) when the latch enable is HIGH. This allows DM9368s to be driven from an MOS device in multiplex mode without the need for drivers on the data lines. The DM9368 also has provision for automatic blanking of the leading 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 fraction decimal representation, using the automatic blanking capability, 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 significant 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 fractional 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. A suitable signal can be generated for this purpose by forming a variable frequency multivibrator with a cross coupled pair of TTL or DTL gates.
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DM9368
Logic Diagram
Numerical Designations
Parallel Data Display System with Ripply Blanking
Common Cathode LED Display
3
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DM9368
Display Demultiplexing System with Ripple Blanking
Common Cathode LED Display
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.
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DM9368
Absolute Maximum Ratings(Note 1)
Supply Voltage Input Voltage Operating Free Air Temperature Range Storage Temperature Range 7V 5.5V 0C to +70C
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.
-65C to +150C
Recommended Operating Conditions
Symbol VCC VIH VIL IOH IOL TA tS(H) tH(H) tS(L) tH(L) tW(L) IOH IOL Supply Voltage HIGH Level Input Voltage LOW Level Input Voltage HIGH Level Output Current LOW Level Output Current RBO Free Air Operating Temperature Setup Time HIGH An to LE Hold Time HIGH An to LE Setup Time LOW An to LE Hold Time LOW An to LE LE Pulse Width LOW Segment Output HIGH Current Segment Output LOW Current 0 30 0 20 0 45 Parameter Min 4.75 2 0.8 Nom 5 Max 5.25 Units V V V
-80
3.2 70
A
mA
C
ns ns ns ns ns
-16 -250
-22
250
mA
A
Electrical Characteristics
Over recommended operating free air temperature range (unless otherwise noted) Symbol VI VOH VOL II IIH IIL IOS ICC 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 VCC = Min, II = -12 mA VCC = Min, IOH = Max, VIL = Max VCC = Min, IOL = Max, VIH = Min VCC = Max, VI = 5.5V VCC = Max, VI = 2.4V VCC = Max, VI = 0.4V VCC = Max (Note 3) VCC = Max, Outputs OPEN, Data & Latch Inputs = 0V
Note 2: All typicals are at VCC = 5V, TA = 25C. Note 3: Not more than one output should be shorted at a time.
Min
Typ (Note 2)
Max -1.5
Units V V
2.4
3.4 0.2 0.4 1 40 -1.6
V mA A mA mA mA
-18
-57 67
Switching Characteristics
VCC = 5.0V, TA = 25C Symbol tPLH tPHL tPLH tPHL Propagation Delay An to a-g Propagation Delay LE to a-g Parameter CL = 15 pF, RL = 100 Min Max 50 75 70 90 ns ns Units
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DM9368 7-Segment Decoder/Driver/Latch with Constant Current Source 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. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems 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. www.fairchildsemi.com 6 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com

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