74LS48 - National Semiconductor

TL/F/10172

DM74LS48 BCD to 7-Segment Decoder

January 1992

DM74LS48

BCD to 7-Segment Decoder

General Description

The ’LS48 translates four lines of BCD (8421) input data

into the 7-segment numeral code and provides seven corre-

sponding outputs having pull-up resistors, as opposed to

totem pole pull-ups. These outputs can serve as logic sig-

nals, with a HIGH output corresponding to a lighted lamp

segment, or can provide a 1.3 mA base current to npn lamp

driver transistors. Auxiliary inputs provide lamp test, blank-

ing and cascadable zero-suppression functions.

The ’LS48 decodes the input data in the pattern indicated in

the Truth Table and the segment identification illustration.

Connection Diagram

Dual-In-Line Package

TL/F/10172–1

Order Number DM74LS48M or DM74LS48N

See NS Package Number M16A or N16E

C1995 National Semiconductor Corporation RRD-B30M105/Printed in U. S. A.

Absolute Maximum Ratings (Note)

Supply Voltage 7V

Input Voltage 7V

Operating Free Air Temperature Range

DM74LS 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 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

Recommended Operating Conditions

Symbol Parameter DM74LS48 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 b50 mA

IOL Low Level Output Current 6.0 mA

TAFree Air Operating Temperature 0 70 §C

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

18 mA b1.5 V

VOH High Level Output VCC Min, IOH eMax, 2.4 V

Voltage VIL eMax

IOFF Output High Current VCC eMin, VOe0.85V b1.3 mA

Segment Outputs

VOL Low Level Output VCC eMin, IOL eMax, 0.5

Voltage VIH eMin V

IOL e2.0 mA, VCC eMin 0.4

IIInput Current @Max VCC eMax, VIe7V 0.1 mA

Input Voltage

IIH High Level Input Current VCC eMax, VIe2.7V 20 mA

IIL Low Level Input Current VCC eMax, VIe0.4V b0.4 mA

IOS Short Circuit VCC eMax, VOe0V b0.3 b2mA

Output Current at BI/RBO (Note 2)

ICCH Supply Current VCC eMax, VIN e4.5V 38 mA

Note 1: All typicals are at VCC e5V, TAe25§C.

Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.

Switching Characteristics at VCC e5V and TAe25§C

Symbol Parameter CLe15 pF Units

Min Max

tPLH Propagation Delay Time 100 ns

tPHL Anto a– g 100

tPLH Propagation Delay Time 100 ns

tPHL RBI to a– f 100

Note: LT eHIGH, A0–A3eHIGH.

Numerical DesignationsÐResultant Displays

TL/F/10172–4

Truth Table

Decimal Inputs Outputs

Function LT RBI A3A2A1A0BI/RBO abcdefg

0 (Note 1) H H L L L L H H H H H H H L

1 (Note 1) H X L L L H H L H H LLLL

2 H X L L H L H HHLHHLH

3 H X L L H H H HHHHLLH

4 H X L H L L H LHHLLHH

5 H X L H L H H HLHHLHH

6 H X L H H L H L LHHHHH

7 H X L H H H H HHHLLLL

8 H X H L L L H HHHHHHH

9 H X H L L H H HHHL LHH

10 H X HLHL H LLLHHLH

11 H X H L H H H LLHHLLH

12 H X H H L L H LHLLLHH

13 H X H H L H H HLLHLHH

14 H X H H H L H L L LHHHH

15 H X H H H H H LLLLLLL

BI (Note 2) X X X X X X L L L L LLLL

RBI (Note 3) H L L L L L L L L L LLLL

LT (Note 4) L X X X X X H H H H HHHH

Note 1: BI/RBO is wired-AND logic serving as blanking input (BI) and/or ripple-blanking output (RBO). The blanking out (BI) must be open or held at a HIGH level

when output functions 0 through 15 are desired, and ripple-blanking input (RBI) must be open or at a HIGH level if blanking of a decimal 0 is not desired. X einput

may be HIGH or LOW.

Note 2: When a LOW level is applied to the blanking input (forced condition) all segment outputs go to a LOW level, regardless of the state of any other input

condition.

Note 3: When ripple-blanking input (RBI) and inputs A0,A

, and A3are at LOW level, with the lamp test input at HIGH level, all segment outputs go to a LOW

level and the ripple-blanking output (RBO) goes to a LOW level (response condition).

Note 4: When the blanking input/ripple-blanking output (BI/RBO) is open or held at a HIGH level, and a LOW level is applied to lamp test input, all segment outputs

go to a HIGH level.

Logic Symbol

TL/F/10172–2

VCC ePin 16

GND ePin 8

Logic Diagram

TL/F/10172–3

Physical Dimensions inches (millimeters)

16-Lead Small Outline Molded Package (M)

Order Number DM74LS48M

NS Package Number M16A

DM74LS48 BCD to 7-Segment Decoder

Physical Dimensions inches (millimeters) (Continued)

16-Lead Molded Dual-In-Line Package (N)

Order Number DM74LS48N

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

to the user.

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