When selecting non-volatile memories for space applications (such as EEPROM, Flash…), one will most likely turn to specific areas of interest for space applications, such as radiation performance, quality level, specific tests that must be performed during procurement etc. However, it is important not to forget about the basic features of non-volatile memories, which is the fact that non-volatile memories are capable of retaining the information even though the power has been switched off.
Commercial parts will have TID ranges between 3-30 krad(Si)and SEL and SEU ranges between 1-120 MeV. Of course, commercial parts are not designed with radiation performance in mind. Nevertheless, a few commercial ICs have in fact exhibited acceptable radiation hardened characteristics.
Each method has its pros and cons. Which method or combination of methods is best will be hotly debated in the years to come? The case study outlined here demonstrates the significant cost savings that can be realized when answering the question, “How rad hard do I need?” and when considering the use of commercially based parts.
Traditional radiation-hardened or “rad-hard” parts are generally considered to be capable of withstanding the most severe space environments. In fact, these devices are designed and fabricated with the specific goal of enduring the harshest space radiation environments.
EEPROM devices are especially critical in the design since they are used to upload the instruction to the microprocessors and other configurable devices (boot code of these parts); this is, as configuration memories. Also, they are used to store debugging information, which is key to depurate errors in configurable devices. Any modification of its content because of a bit error (1 to 0 or 0 to 1) due to radiation causes could lead to major consequences.
Data Device Corporation (DDC) has compiled a list of frequently asked questions related to its EEPROM family.
The DDC family of EEPROMs are in-circuit programmable. For applications where the device must be programmed prior to insertion there are a number of programmers that can be used to program DDC’s EEPROM devices.