A scientific study of the problems of digital engineering for space flight systems,
with a view to their practical solution.

Figures 1-7 are missing; I am trying to get them.

Single Event Effect Test Report on the Intel 80386 Microprocessor, 80387 Coprocessor, and 82380 Integrated Peripheral

tested 2/20-21/96

Version 1.0

Amy K. Moran

Kenneth A. LaBel

March 7, 1996


The objective of this study was to determine the threshold linear energy transfers (LETths) and cross-sections for single event upset (SEU) and single event latchup (SEL) due to heavy ions. LETth is defined as the maximum LET at which no errors are seen at a fluence of 1.00E07 particles/cm2. SEU LETth is defined as the minimum LET value to cause an effect at a fluence of 1E7 particles/cm2. SEL LETth is defined as the maximum LET value at which no latchup occurs at a fluence of 1E7 particles/cm2. The saturation cross section of the device is the point at which the cross section curve becomes asymptotic.


Heavy ion single event effect (SEE) testing was performed at Brookhaven National Laboratories' twin Tandem van deGraaff accelerator on February 20-21, 1996 on the following 80386 microprocessors, 80387 Coprocessors, and 82380 Integrated Peripherals:

MFR     Device          Serial #    Date Code   Vcc   Project

Intel   MQ80386-25/B                9442        5     EOS-AM

SEI     H30466A-21      042, 044    9606        5     EOS-AM

Intel   MQ80387-20B                 9415        5     FUSE

Intel   MQ82380-25/B                9446        5     FUSE

The 80386 and 80387 are built on Intel's CHMOS IV process, while the 82380 is on the CHMOS III process. The SEI device is an Intel 80386 die repackaged by SEI into a RadPak(TM).


A. Facility Usage

Testing was performed at the Brookhaven National Laboratories (BNL) Single Event Upset Test Facility (SEUTF). This setup utilizes a dual Tandem Van De Graaff accelerator suitable for providing ions and energies for SEU testing. The test devices are mounted on a device-under-test (DUT) board inside a vacuum chamber.

The SEUTF uses a computer-driven monitor and control program to provide a user-friendly interface for running the experiments. Hard copies of the test data and graphs are also made available.

B. Test Hardware, Software and Control

The 80386, 80387, and 82380 devices were tested using a single-board computer. Custom software exercised the devices by performing memory accesses, addressing, data transfers, and numerical calculations.

C. Device Test Procedure

The test procedure was similar for all devices tested. Test mode used was dynamic: While being irradiated,
Device is exercised using a software routine (mimicing worst-case spacecraft operations), which performs addressing, memory accesses and other operations. External clock speed is 16 MHz.
Three types of SEU were observed:
Count: the device fails to write to a test address, or it performs a memory transfer or calculation incorrectly.

Reset: the device locks up, Icc remains at nominal operating level, and the condition is cleared by a reset signal (power is not cycled). Most likely the SEU, either alone or through propagation to the system, places the test device or a peripheral into an unknown state.

Lockup: the device locks up, Icc drops to a current indicative of standby operating mode, and the condition requires a power reset to recover. Most likely the SEU places the test device or a peripheral into an undefined, test, or standby mode. Test runs were halted upon lockup.

Additionally, two types of latchup were observed:
SEL: device Icc increases above the specified max for the device. A power reset is required to clear the condition.

Microlatch: device Icc increases above normal operating level, but stays below the specified max for the device. A power reset is required to clear the condition.

SEUs in a test device may disrupt the system in numerous ways, causing the reset and lockup SEUs described above. For example, the 82380 is an integrated peripheral, performing DMA transfers, interrupt and timing generation, etc. An SEU in the 82380 may cause it to improperly generate an interrupt; while the cause is an 82380 SEU, the symptom will be an error on the 80386. Likewise, an SEU in the 80387 math coprocessor may cause it to return the wrong value for an 80386 calculation, sending the microprocessor, and therefore the system, into an undefined state.

Vcc and Vcc+/-5% were used for testing. Nominal Icc levels were:

Device          Icc typical (mA)   Icc max (mA) for SEL

MQ80386-25/B    134                680

H30466A-21      134                680

MQ80387-20B     60                 310

MQ82380-25/B    40                 375

Two to three samples, typically, were tested per device type.

Ions used for testing were:

Ion      Energy (MeV)   Linear Energy Transfer (LET)

                        in MeV*cm2/mg at normal incidence

F-19     140            3.38

Cl-35    188            12.0

Ni-58    280            26.2

Br-75    290            37.1

I-127    345            59.9

Energy and LET varied slightly among the three test dates. Intermediate LETs were achieved by varying the beam's angle of incidence to the package. Temperature was a nominal 25 deg C.

Fluxes: 7.2E2 to 2.6E4 particles /cm2/sec
Fluences: 1E6 particles /cm2


All LETs are in MeV*cm2/mg.

Intel MQ80386-25/B
The LETth (threshold) is between 4-5 for count and reset SEUs, and between 5-6 for lockup SEUs. During lockup, the device current dropped from normal operating current of 134mA to ~100mA; the device is suspected to be entering a standby mode. Figure 1 displays combined SEU data, while Figures 2, 3, and 4 display count, reset, and lockup SEUs respectively.
"Traditional" SEL (Icc > maximum for the device) was not seen on any test run. However, microlatch was observed, with an LETth between 30 and 32. A two-minute dwell test was performed following a microlatch; the device recovered fully following a power reset. SEL data for all 80386 devices tested is presented in Figure 5.
SEI H30466A-21
LETth is between 5-6 for count SEUs, between 3.4-5 for reset SEUs, and between 6-11.4 for lockup SEUs. Figure 6 displays total SEUs.
"Traditional" SEL (Icc > maximum for the device) was not seen on any test run. However, microlatch was observed, with LETth between 35-37.5. A 15-minute dwell test was performed, with the device in a microlatch state; the device recovered fully following a power reset. Figure 7 displays microlatch data.
Intel MQ80387-20B
The LETth is between 9-11.4. Only count and reset SEUs were seen; lockup SEUs were not. Figure 8 displays data for count and reset SEU.
LETth for microlatch SEL was between 32 and 35. During a microlatch, the current jumped from a typical 60mA to between 154-223mA. The device remained functional during a microlatch; upon a reset signal, the device would functionally recover, while the current remained at the higher microlatch level. A power reset brought the current back to normal levels. Additionally, a 15-minute dwell test was performed, with the device in this microlatch state. The device recovered fully following a power reset. "Traditional" SEL was not observed. Figure 9 displays microlatch data.
Intel MQ82380-25/B
LETth for reset SEUs was ~ 3.4. Count and lockup SEUs were not observed. Figure 10 displays SEU data.
Both microlatch and "traditional" SEL were observed, with an LETth between 15-20. During several test runs, the device experienced a traditional SEL (with a device current of 387mA, exceeding the specified maximum of 375mA), which was cleared entirely by a software reset. It is suspected that the device actually experienced an SEU which placed it in an undocumented test mode.

82380 SEL testing was complicated by the fact that the 82380 and 80386 currents were coupled; whenever the 82380 experienced SEL, the 80386 showed a corresponding increase in current, most likely due to a bus contention, as seen in the diagram to the right. Despite this coupling, a two-minute dwell test was performed. The 82380 and 80386 both recovered fully, following a power reset. Figure 11 displays both microlatch and SEL data.


We typically divide SEE test results into the following four categories:
Category 1
Recommended for usage in all spaceflight applications.
Category 2
Recommended for usage in spaceflight applications, but may require some SEE mitigation techniques.
Category 3
Recommended for usage in some spaceflight applications, but requires extensive SEE mitigation techniques or SEL recovery mode.
Category 4
Not recommended for usage in any spaceflight applications.
Category 3 devices for this test trip are:
All the 80386 and 80387 devices tested.
Category 4 devices for this test trip are:
The 82380 devices. They may be used but require very extensive SEU and SEL mitigation.


Special thanks to the test team as well as to Doug Connelly of OSC for participating in the test.

Last Revised: February 03, 2010
Digital Engineering Institute
Web Grunt: Richard Katz