74147 (BCD to 10-line decimal decoder/driver)

The 74147 is a BCD to 10-line decimal decoder/driver with priority encoding. This IC is part of the 7400 series and is used to convert Binary Coded Decimal (BCD) input into a decimal output, but with a special feature: priority encoding.

74147 IC Description:

The 74147 is a BCD to decimal decoder that provides an active-low output for the decimal digits 0 through 9. It has a priority encoding function, meaning it can select the lowest (priority) active input if multiple inputs are active at the same time. This feature makes it suitable for applications where a priority-based encoding or decoding is required.

Key Features:

• BCD to 10-line Decimal Decoder: The IC converts BCD (binary coded decimal) inputs into one of 10 decimal outputs (0 to 9).
• Priority Encoding: The IC includes priority encoding, meaning if multiple BCD inputs are active at the same time, the IC will select the lowest active input.
• Active-Low Outputs: The outputs are active-low, meaning the output corresponding to the BCD input is pulled low (0), and all other outputs remain high (1).
• Input Range: It accepts a 4-bit BCD input (A, B, C, D), which represents a decimal value between 0 and 9.
• Unused Input Handling: If the BCD input is greater than 9 (i.e., 1010 to 1111 in binary), none of the outputs will be active.

Pin Configuration (16-pin package):

Here’s the pinout for the 74147 BCD to 10-line decimal decoder/driver:

1. Pin 1 (A): BCD input bit 1 (Least Significant Bit).
2. Pin 2 (B): BCD input bit 2.
3. Pin 3 (C): BCD input bit 3.
4. Pin 4 (D): BCD input bit 4 (Most Significant Bit).
5. Pin 5 (9): Active-low output for decimal digit 9.
6. Pin 6 (8): Active-low output for decimal digit 8.
7. Pin 7 (7): Active-low output for decimal digit 7.
8. Pin 8 (GND): Ground connection (GND).
9. Pin 9 (6): Active-low output for decimal digit 6.
10. Pin 10 (5): Active-low output for decimal digit 5.
11. Pin 11 (4): Active-low output for decimal digit 4.
12. Pin 12 (3): Active-low output for decimal digit 3.
13. Pin 13 (2): Active-low output for decimal digit 2.
14. Pin 14 (1): Active-low output for decimal digit 1.
15. Pin 15 (Enable): Active-low enable input.
16. Pin 16 (Vcc): Supply voltage (typically 5V).