White Paper: Single Event Latchup Protection Of Integrated Circuits
By P. Layton, D. Czajkowski, J. Marshall, H. Anthony, R. Boss
Maxwell Technologies Microelectronics
Introduction
Many commercially available advanced technology CMOS and bipolar integrated circuits are latchup susceptible to single event effects caused by heavy ions or protons from cosmic rays or solar flares making them unsuitable for satellite applications. Remanufacturing the integrated circuits on an inherently SEL immune process has been an expensive and technically difficult option as is the alternate option of incorporating latchup protection and recovery circuitry in the spacecraft system electronics.
Maxwell Technologies Microelectronics has developed several different circuits which provide protection and recovery of integrated circuits known to exhibit single event induced latchup. These circuits are integrated within the same package as the susceptible integrated circuit using MCM and modern packaging technology resulting in a device level solution providing minimum cost and minimum impact on the system.
The LPT™ circuit was designed to provide the following features to protect and recover the susceptible integrated circuit device:
a. Provide current limiting to the device.
b. Detect the increase in current during the SEL event above a preset threshold.
c. Force a shutdown of the protected device when the threshold is exceeded.
d. Hold the device in the shut down mode for a preset time interval.
e. Return the device supply voltage to its original operating level.
The LPT™ circuitry (patent pending) has the potential to be applied to a wide variety of susceptible devices. The specific implementation details such as current latchup protection threshold and supply off time are determined by characterization of the susceptible devices at a heavy ion facility. The LPT™ device impacts a satellite component system by converting a Single Event Latchup (SEL) into a recoverable event. Using mission specific or orbit radiation data, recoverable event rates can be calculated. The rate and number of these recoverable events is dependent on the fluence, energy, and species of radiation encountered by the device during the particular mission [1].
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