The ISL70591SEH is a radiation hardened precision 100µA current source IC. The device has excellent accuracy of ±1% over a wide operating voltage range of 3V to 40V and over a temperature range of -55°C to +125°C. Fabricated with the Renesas proprietary PR40 Silicon-on-Insulator (SOI) process, the device is immune to single-event latch-up. The high output impedance of the device makes it insensitive to voltage drops across long lines. It can withstand a forward operating voltage of 40V and a reverse voltage of -0.5V. The ISL7x591SEH and ISL7x592SEH are two-terminal floating current sources allowing them to be used in high-side, low-side, and dual-side load applications such as sensor excitation, biasing networks, low-voltage references, floating voltage references, and ramp generators. The current sources were primarily designed for thermistor and other sensor excitation applications widely used in spacecraft. The device is available in a 4 Ld ceramic flatpack and die forms. The temperature range is -55°C to +125°C.