Decoding IC 74LS47 7 segment LED

Click to enlarge

Video demo

Function: 
- One of the most popular electronic IC number. There are many different symbols depending on the firm and ability to meet such as 74HC47, 74HCT47, 74LS47,. 
Application: 
This is a sign dedicated decoder IC for LED 7-segment common anode. Application when it needs to display the number on the LED 7-in digital circuit without using the processor or want to save the foot.'' 
 
The mode of operation: 
- Map of principle: As the diagram above, in which A, B, C, D (Connect with the processor, pulse the counter ,...), BI / RBO, RBI, LT (7447 foot control, depending on different needs will be connected), Chan QA, QB, QC, QD, QE, QF, QG, respectively connected to pin a, b, c, d, e, f, g of common anode 7-segment LED. 
- Describe how the following activities:  
PORT A, B, C, D: input of 7447, receiving the binary value (BCD) from 0 to 15, corresponding to each value received will decode the output Q, respectively. 
QA-QG PORT: Connect directly to LED 7 = a bar with QA, QB = b, c = QC, QD = d, e = QE, QF = f, QG = g, the value displayed on the LED 7-dependent the input value Porta, B, C, D in the following table; 

BI / RBO, RBI, LT: 7447 Chan's control, to understand you need to read and understand the following logic table (IC 7447 To enable the connection works just BI / RBO = LT = 1): 
The downside, cost IC pins, use 7-segment LED scanning method is more effective to use transistor, IC pins support costs