74Ls48

SN54/74LS48 BCD TO 7-SEGMENT DECODER
The SN54 / 74LS48 is a BCD to 7-Segment Decoder consisting of NAND gates, input buffers and seven AND-OR-INVERT gates. Seven NAND gates and one driver are connected in pairs to make BCD data and its complement available to the seven decoding AND-OR-INVERT gates. The remaining NAND gate and three input buffers provide lamp test, blanking input/rippleblankinginput for the LS48. The circuit accepts 4-bit binary-coded-decimal (BCD) and, depending on the state of the auxiliary inputs, decodes this data to drive other components. The relative positive logic output levels, as well as conditions required at the auxiliary inputs, are shown in the truth tables. The LS48 circuit incorporates automatic leading and / or trailing edge zero-blanking control (RBIand RBO). Lamp Test (LT) may be activated any time when the BI / RBO node is HIGH. Both devices contain an overriding blanking input (BI) which can be used to control the lamp intensity by varying the frequency and duty cycle of the BI input signal or to inhibit the outputs. • Lamp Intensity Modulation Capability (BI/RBO) • Internal Pull-Ups Eliminate Need for External Resistors • Input Clamp DiodesEliminate High-Speed Termination Effects CONNECTION DIAGRAM DIP (TOP VIEW)
VCC 16 f 15 g 14 a 13 b 12 c 11 d 10 e 9 D SUFFIX SOIC CASE 751B-03

BCD TO 7-SEGMENT DECODER
LOW POWER SCHOTTKY

J SUFFIX CERAMIC CASE 620-09
16 1

16 1

N SUFFIX PLASTIC CASE 648-08

16 1

1 B

2 C

3

4

5

6 D

7 A

8 GND

ORDERING INFORMATION
SN54LSXXJ SN74LSXXN SN74LSXXD
a

LT BI /RBO RBI

LOGIC DIAGRAM

Ceramic Plastic SOIC

A b B INPUT C D d BLANKING INPUT OR RIPPLE-BLANKING OUTPUT c OUTPUT

LOGIC SYMBOL
7 1 2 6 3 5

A B C D LT RBI SN54 / 74LS48 a b c d e BI/ f g RBO

e

13 12 11 10 9 15 14 4 VCC = PIN 16 GND = PIN 8

RIPPLE-BLANKING INPUT LAMP-TEST INPUT

f

g

FAST AND LS TTL DATA 5-59

SN54/74LS48
PIN NAMES HIGH A, B, C, D RBI LT BI / RBO BIBCD Inputs Ripple-Blanking (Active Low) Input Lamp-Test (Active Low) Input Blanking Input or RippleBlanking Output (Active Low) Blanking (Active Low) Input 0.5 U.L. 0.5 U.L. 0.5 U.L. 0.5 U.L. 1.2 U.L. 0.5 U.L. Open-Collector LOADING (Note a) LOW 0.25 U.L. 0.25 U.L. 0.25 U.L. 0.75 U.L. 2(1) U.L. 0.25 U.L. 3.75 (1.25) U.L. (48)

NOTES: a) Unit Load (U.L.) = 40 µA HIGH / 1.6 mA LOW b) Outut currentmeasured at VOUT = 0.5 V Output LOW drive factor is SN54LS / 74LS48: 1.25 U.L. for Military (54), 3.75 U.L. for Commercial (74).

0

1

2

3

4

5

6

7

8

9

10

11 12

13

14

15

NUMERICAL DESIGNATIONS — RESULTANT DISPLAYS

TRUTH TABLE SN54 / 74LS48
INPUTS DECIMAL OR FUNCTION 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 BI RBI LT OUTPUTS

LT H H H H H H H H H H HH H H H H X H L

RBI H X X X X X X X X X X X X X X X X L X

D L L L L L L L L H H H H H H H H X L X

C L L L L H H H H L L L L H H H H X L X

B A L L H L H L

BI / RBO H H H H H H H H H H H H H H H H L L H

a H L H H L H L H H H L L L H L L L L H

b H H H H H L L H H H L L H L L L L L H

c H H L H H H H H H H L H L L L L L L H

d H L H H L H H L H L H H L H H L L L H

e H L HL L L H L H L H L L L H L L L H

f H L L L H H H L H H L L H H H L L L H

g L L H H H H H L H H H H H H H L L L H

NOTE 1 1

H H L L H L H L

H H L L H L H L

H H L L H L H L

H H X L X X L X

NOTES: (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 0through 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=input may be HIGH or LOW. (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. (3) When ripple-blanking input (RBI) and inputs A, B, C, and D are at LOW...