The ISL71840SEH, 30V, 16-channel multiplexer is a drop-in replacement for Intersil’s   HS9-1840ARH, which has been aboard nearly every satellite and space exploration mission, including NASA’s recent Orion spacecraft flight test. For applications with form factor constraints, the ISL71841SEH is a 30V, 32-channel multiplexer offering 41% reduced board space compared with an ISL71840SEH two-chip solution.

Both use the company’s silicon on insulator process, which provides single event latch-up (SEL) robustness in heavy ion environments. The enhanced 8kV ESD protection eliminates the need for costly external protection diodes on the input pins, while reduced R_ON (500Ω at ±5V) and propagation delays of less than 800ns increase the overall performance and accuracy of telemetry signals processed and multiplexed into an ADC input.

Over-voltage protection is on a per-switch basis to maintain the continuous processing of telemetry test points. If any input channel experiences an over-voltage condition, the remaining channels continue sending data to the ADC. Both multiplexers provide a “cold spare” redundant capability, allowing the connection of two to three additional unpowered multiplexers to a common data bus. This is an especially important feature for mission-critical space flights lasting up to 20 years. If required for any reason, a redundant multiplexer is immediately activated. Both multiplexers provide a wide supply range with split-rail operation from ±10.8 to 16.5V and an absolute maximum of ±20V.

The multiplexers deliver 8kV human body model (HBM) ESD protection and provide true rail-to-rail operation. They have  high dose rate (50-300rad(Si)/s) radiation tolerance of 100krad(Si) and low dose rate (0.01rad(Si)/s) radiation tolerance of 50krad(Si). 

The ISL71840SEH is available in a 18.8 x 14mm, 28-lead ceramic flatpack package, and the ISL71841SEH in a 14 x 14mm, 48-lead ceramic quad flatpack. Both multiplexers are also available in die form. Two evaluation boards are also available - the 16-channel ISL71840SEHEVAL1Z and 32-channel ISL71841SEHEVAL1Z.