"Texas Instruments Digital Signal Processor (TI-DSP) SMJ320F240"
A.B. Sanders1, C. Poivey2, H.S. Kim2, G. Gee2, D. Sheppard1
This study was undertaken to determine the Single Event Latch-up (SEL) susceptibility of Texas Instruments Digital Signal Processor (TI-DSP) SMJ320F240 for the Sample Analysis at Mars (SAM) Instrument as a part of the Mars Science Laboratory (MSL) Project. The DSP was intended to drive the motor of the SAM Instrument.
The DSP is a High-Performance Static CMOS Technology. The device was packaged in a 132 pin ceramic quad flatpack. The DSP was tested using an Evaluation Board made by Spectrum Digital, which the Device Under Test (DUT) was mounted upon for latchup testing. The JTAG was used for programming or flashing of the EEPROM to utilize the watch dog timer, memory, matrix, and calculation tests, as well as read switches and I/O. The analog and digital current for the DUT were monitored separately via cables to the Evaluation Board. The DAC (MP7680JE), and the DFF (TLC2272) devices were removed from the Evaluation Board, which left the VCCA only connected to the DUT and not the external circuitry. The digital current was monitored by placing an amp meter in series with the Inductor (L3), on the Evaluation Board.
The device was monitored for current increases which can be destructive events induced by exposing it to a heavy ion beam at the Texas A&M University Cyclotron Single Event Effects Test Facility. The DSP test devices experienced SEL < LET of 2.8 MeV/(mg/cm2) at the nominal rated supply voltage. An equivalent normal-incidence fluence of at least 1x107 ions/cm2 was used at each test condition unless an SEL occurred. A beam flux range of 1.2 x 103 to 9.4 x 104 particles/cm2/s resulted in individual exposures between 1.05 seconds and 9 minutes and seconds. These early findings before the Preliminary Design Review (PDR) enabled the SAM Instrument team to choose a different device for the mission that was more radiation tolerant.
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