7448 BCD TO 7-SEGMENT DECODER

The 7448 belongs to the 74-series TTL logic family and functions as a BCD-to-7-segment decoder/driver. It accepts a 4-bit BCD input (D0–D3) and produces seven outputs (a–g) to drive a 7-segment display. It includes active-low outputs, lamp test, blanking, and ripple-blanking inputs for flexible display control. The SN54 /74LS48 is a BCD to 7-Segment Decoder consisting of NAND gatesinput 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 testblanking input/rippleblanking input for the LS48. The circuit accepts 4-bit binary-coded-decimal (BCD) anddepending on the state of the auxiliary inputsdecodes this data to drive other components. The relative positive logic output levelsas well as conditions required at the auxiliary inputsare shown in the truth tables. The LS48 circuit incorporates automatic leading and/or trailing edge zero-blanking control (RBI and 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 Diodes Eliminate High-Speed Termination Effects