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## CD4028 - BCD to Decimal Decoder IC

## CD4028 - BCD to Decimal Decoder IC

CD4028 is a BCD to decimal or binary to octal decoder consisting of 4 inputs and 10 output buffers. A BCD code is applied to the 4 inputs, A, B, C, and D. Thus resulting in a high level at the selected 1-of-10 decimal decoded outputs. Similarly, a 3-bit binary code applied to inputs A, B, and C is decoded into octal at outputs 0–7. A high-level signal at the D input inhibits octal decoding and causes outputs 0–7 to go LOW.

The IC is always available in a 16 – pin hermetically sealed dual inline IC package (DIP), making it easy to interface with TTL, CMOS, and NMOS devices. The IC offers many features such as high noise immunity and low thermal dissipation. High drive capability is provided at all outputs to enhance dc and dynamic performance in high fan- ut applications. Meanwhile, all the inputs are protected against static discharge damage by diode clamps to V_{DD} and V_{SS}.

A BCD to Decimal Decoder is defined as a simple logic circuit that can translate a BCD (binary coded decimal) input into a decimal (0 – 9) output In any BCD to decimal decoder, the inverters are connected in pairs to make BCD input data available for decoding by the NAND gates. Full decoding of valid BCD input logic ensures that all outputs remain OFF for all invalid binary input conditions. Moreover, these decoders feature TTL inputs and high–performance NPN output transistors designed for use as indicator/relay drivers or as open–collector logic circuit drivers.

## Application

- Code conversion
- Address decoding
- Indicator-tube decoder

## Package Includes:

Selected qty of IC - CD4028

## Specifications:

Supply Voltage Range | 3 to 20V |

Input or Output Current | ±10mA |

Power Dissipation | 500mW |

Low-level Output Voltage Max | 0.05V |

High-level Output Voltage Min | 4.95V |

Low-level Input Voltage | 2.25V |

High-level Input Voltage | 2.75V |

Propagation Delay Time Max | 600ns |

Package | DIP-16 |

### 1.How many and gates are required for a BCD-to-decimal decoder?

- A BCD-to-decimal decoder is a digital circuit that converts a binary-coded decimal (BCD) number into a decimal number. BCD is a digital representation of decimal numbers in which each decimal digit is represented by a four-bit binary number. To implement a BCD-to-decimal decoder, you will need to use AND gates. The number of AND gates required will depend on the design of the decoder and the specific implementation.
- One way to implement a BCD-to-decimal decoder is to use a one-hot encoding for the BCD input, in which each decimal digit is represented by a unique combination of four binary digits. For example, the BCD digit "0" might be represented by "0000", the digit "1" by "0001", and so on. In this case, you would need 4 AND gates, one for each binary digit, to decode the BCD input.

### 2.What is encoder decimal to BCD encoder?

- A decimal-to-BCD encoder is a digital circuit that converts a decimal number into a binary-coded decimal (BCD) representation. BCD is a way of representing decimal numbers in which each decimal digit is represented by a four-bit binary number. There are several ways to implement a decimal-to-BCD encoder. One approach is to use a lookup table to map the decimal input to the corresponding BCD output. In this case, the encoder would simply look up the BCD value for the given decimal input in the lookup table and output the result.
- Another approach is to use digital logic gates, such as AND gates, OR gates, and NOT gates, to implement the encoder. This approach may involve dividing the decimal input into its individual digits, encoding each digit separately, and then combining the encoded digits to produce the BCD output. The specific number of AND gates required will depend on the design of the encoder. It's also possible to implement a decimal-to-BCD encoder using other types of digital circuits, such as flip-flops or counters. The specific implementation will depend on the requirements of the specific application.

### 3.How do you convert binary to octal?

- To convert a binary number to octal, you can follow these steps:
- Group the binary number into groups of three bits, starting from the rightmost side of the number.
- If the binary number does not have a multiple of three bits, add enough 0s to the left side of the number to make it a multiple of three.
- For each group of three bits, find the corresponding octal digit by looking up the value in a binary-to-octal conversion table.
- Write the octal digits in the order that they were obtained, starting from the leftmost side of the number.

- For example, to convert the binary number 1010101 to octal:
- Group the binary number into groups of three bits: 101 010 101
- Find the corresponding octal digits for each group of three bits using the conversion table: 5 2 5
- Write the octal digits in the order that they were obtained: 525

- Here is the binary-to-octal conversion table:

Binary | Octal |
---|---|

000 | 0 |

001 | 1 |

010 | 2 |

011 | 3 |

100 | 4 |

101 | 5 |

110 | 6 |

111 | 7 |

- Note that this method is only suitable for converting small binary numbers to octal. For larger numbers, it may be more efficient to use a different method, such as converting the binary number to decimal and then converting the decimal number to octal.

### 4.Why do we convert binary to octal?

- There are several reasons why it might be useful to convert a binary number to octal:
**Compact representation**: Octal is a base-8 numbering system, which means that each octal digit represents a value that is a power of 8. This can be more compact than representing the same value in binary, which is a base-2 numbering system. For example, the octal number 777 represents the same value as the binary number 111110111, but uses fewer digits.**Ease of use**: Octal is often used in computing and digital systems because it is easy to convert to and from other numbering systems, such as binary and decimal. This can make it easier to work with binary numbers, especially when dealing with large numbers or when performing arithmetic operations.**Compatibility with other systems**: Many computer systems, such as operating systems and programming languages, use octal notation to represent certain values. Converting binary numbers to octal can make it easier to work with these systems, as it allows you to use the octal notation that is native to the system.**Data storage**: Octal can be used to store binary data in a compact and easy-to-read format. For example, a file containing a large amount of binary data might be stored in octal format to make it easier to read and edit.

- Overall, converting binary to octal can be useful in a variety of situations where compact representation, ease of use, compatibility with other systems, or data storage are important considerations.