IC 7448 (BCD TO 7-SEGMENT DECODER DRIVER)

The 7448 Decoder feature active-high outputs for driving lamp buffers or common-cathode LEDs. They have full ripple-blanking input/output controls and a lamp test input. Display patterns for BCD input counts above 9 are unique symbols to authenticate input conditions.

Their circuits incorporate automatic leading and/or trailing-edge zero-blanking control (RBI\ and RBO\). Lamp test (LT\) of these types may be performed at any time when the BI\/RBO\ node is at a high level. They contain an overriding blanking input (BI\) which can be used to control the lamp intensity by pulsing or to inhibit the outputs. Inputs and outputs are entirely compatible for use with TTL logic outputs.

The circuit accepts 4-bit binary-coded-decimal (BCD) and, depending on the state of the auxiliary inputs, decodes this data to drive other components. The relative positive logic output levels, as well as conditions required at the
auxiliary inputs, are shown in the truth tables.