BCD-to-Seven-Segment Decoder / Driver (internal pull-up outputs)

The HD74LS248 is electrically and functionally identical to the HD74LS48, respectively, and has the same pin assignments as its equivalents. It can be used interchangeably in present or future designs to offer designers a choice between two indicator fonts. The HD74LS48 composes the 6 and the 9 without tails and the HD74LS248 composes the 6 and the 9 with tails. Composition of all other characters, including display patterns for BCD inputs above nine, is identical. The HD74LS248 features active-low outputs designed for driving indicators directly. All of the circuits have full ripple-blanking input / output controls and a lamp test input. Segment identification and resultant displays are shown below. Display patterns for BCD input count above 9 are unique symbols to authenticate input conditions. This circuit incorporates automatic leading and / or trailing-edge zero-blanking control (RBI and RBO).