The QS3251 is a high-speed CMOS TTL-compatible 8:1 multiplexer/ demultiplexer. The QS3251 has 3-state outputs. The QS3251 is a function and pinout compatible version of the 74F251, 74FCT251 and the 74ALS/ AS/LS251 8:1 multiplexers. The low ON resistance of the QS3251 allows inputs to be connected to outputs without adding propagation delay and without generating additional ground bounce noise. Mux/Demux devices provide an order of magnitude faster speed than equivalent logic devices. The QS3251 is characterized for operation at -40C to +85C.


  • Enhanced N channel FET with no inherent diode to Vcc
  • 5 ohm bidirectional switches connect inputs to outputs
  • Zero propagation delay, zero ground bounce
  • Undershoot clamp diodes on all switch and control inputs
  • TTL-compatible control inputs
  • Video, audio, graphics switching, muxing
  • Hot-swapping, hot-docking
  • Voltage translation (5V to 3.3V)
  • Available in 16 pin QSOP and S1 packages




Design & Development