BCD-to-Seven Segment Latch/Decoder/Driver for Liquid Crystals

TheMC14543B BCD–to–seven segment latch/decoder/driver is designed foruse with liquidcrystal readouts, and is constructed with complementary MOS(CMOS) enhancement mode devices. The circuit providesthe functionsof a 4–bit storage latch and an 8421 BCD–to–sevensegment
decoder and driver. The device has the capability to invert the logic levels of theoutput combination. The phase (Ph), blanking (BI), and latch disable (LD) inputsare used to reverse the truth table phase, blank the display, and store a BCD code, respectively. For liquid crystal (LC) readouts, a square wave is appliedto the Ph input of the circuit and the electrically common backplane ofthe display. The outputs of the circuit are connected directly to the segments of the LC readout. For other types of readouts, such as light–emitting diode (LED), incandescent, gas discharge, and fluorescent readouts, connection diagrams are given on this data sheet.

• Latch Storage of Code
• Blanking Input
• Readout Blanking on All Illegal Input Combinations
• Direct LED (Common Anode or Cathode) Driving Capability
• Supply Voltage Range = 3.0 V to 18 V
• Capable of Driving Two Low–power TTL Loads, One Low–power Schottky TTL Load or Two HTL Loads Over the Rated Temperature Range
• Pin–for–Pin Replacement for CD4056A (with Pin 7 Tied to VSS).
• Chip Complexity: 207 FETs or 52 Equivalent Gates