Description

7447 DIP BCD To 7-Segment Decoder

• 7447  decodes BCD into 7 Segments, which means it accepts a binary coded decimal or BCD Values as input and decoded into a pattern that drives a 7-segment for displaying digits 0 to 9,
•  Its input is 4 lines BCD data and generates complements as output.
• The generation of complement data of BCD is internally so no coding or programming is required to generate it.
• The 7447 are Low Power Schottky BCD to 7-Segment Decoder/Drivers consisting of NAND gates, input buffers, and seven AND-OR-INVERT gates.
• They offer active LOW, high sink current outputs for driving indicators directly.
• 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/ripple-blanking output, and ripple-blanking input.
•   If the input data is decimal zero, a LOW signal applied to the RBI blanks the display and causes a multi-digit display.
• For example, by grounding the RBI of the highest order decoder and connecting its BI/RBO to RBI of the next lowest order decoder, etc., leading zeros will be suppressed.
• Similarly, by grounding RBI of the lowest order decoder and connecting its BI/RBO to RBI of the next high- est order decoder, etc., trailing zeros will be suppressed.
• Leading and trailing zeros can be suppressed simultaneously by using external gates, i.e.: by driving RBI of intermediate decoder from an OR gate whose inputs are BI/RBO of the next highest and lowest order decoders.
• BI/RBO also serves as an unconditional blanking input.
• The internal NAND gate that generates the RBO signal has a resistive pull-up, as opposed to a totem pole, and thus BI/ RBO can be forced LOW by external means, using wired-collector logic.
• A LOW signal thus applied to BI/RBO turns off all segment outputs.
• This blanking feature can be used to control display intensity by varying the duty cycle of the blanking signal.
• A LOW signal applied to LT turns on all segment outputs, provided that BI/RBO is not forced LOW.
• Large Voltage range
• Has open collector output which directly drives the indicator
• Has a wide range of operating conditions
• No need for external resistors because of internal pull-ups
• No high-speed termination because of the input clamp diode
• 4 the number of input lines and 7 output lines

7447 Decoder Datasheet