The HS-0548RH and HS-0549RH are radiation hardened analog multiplexers with Active Overvoltage Protection and guaranteed rON matching. Analog input levels may greatly exceed either power supply without damaging the device or disturbing the signal path of other channels. Active protection circuitry assures that signal fidelity is maintained even under fault conditions that would destroy other multiplexers. Analog inputs can withstand constant 70V peak-to-peak levels with 15V supplies and digital inputs will sustain continuous faults up to 4V greater than either supply. In addition, signal sources are protected from short circuiting should multiplexer supply loss occur: each input presents 1k of resistance under this condition. These features make the HS-0548RH and HS-0549RH ideal for use in systems where the analog inputs originate from external equipment or separately powered circuitry. Both devices are fabricated with 44V dielectrically isolated CMOS technology. The HS-0548 is an 8 channel device and the HS-0549 is a 4 channel differential version. If input overvoltage protection is not needed, the HS-0508 and HS-509 multiplexers are recommended.