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LM1117T-3.3 Heavy Ion Test

Brookhaven National Labs

April, 1999

Three LM1117T-3.3 low-voltage dropout (LVDO) linear regulators were tested with heavy ions at Brookhaven National Labs in April, 1999.  Three units were tested and were procured as commercial parts.  This device has a dropout voltage of 1.2V @ I=800 mA, making it suitable for producing a 3.3VDC supply from a "standard" 5V logic supply.  Most runs were made with a worst-case max logic supply of Vin = 5.5VDC, although the device, as specified on the data sheet is capable of tolerating higher input voltages.  Some runs were made with a worst-case min logic supply of Vin = 4.5VDC.

The devices all showed fluctations in regulated output voltages during the runs.   Start and end values are listed in the table below.  It is noted that the changes are small and neglible for standard logic circuits.

All three devices passed at Vin = 5.5VDC with Iodine, normal incidence; this is an LET of 59.9 MeV-cm²/mg.  All three devices went into a "latchup-like" state at either 30 degrees (LET of 69.1 MeV-cm²/mg) or at 45 degrees (LET of 84.7 MeV-cm²/mg).  In this mode, the input current increased by about 400 mA and the output went from 3.3VDC to approximately 4.4VDC, until power was removed.  S/N LV1 was destroyed.

A typical strip chart of current during a heavy ion irradiation, when the device enters its high current mode, can be viewed at LM117T-3.3_HighCurrent.pdf

The regulator was loaded with a 66 ohm resistor.  The load circuit can be viewed at: regulator_3volt.PDF

  Summary of Heavy Ion Runs on the LM1117T-3.3 LVDO Regulator

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