part number TPS75933KTTT
BLOWN 3.3V LDO ON 6 VME BOARDS ALL RESIDING IN THE SAME CHASSIS. THERE ARE ALSO 2.5V, 1.2V, AND 1.5V ALL OF THE SAME FAMILY TPS759XXKTTT. OF THESE ONLY THE 3.3 WAS AFFECTED. THESE PROVIDE CORE AND IO VOLTAGE FOR 2 FPGAS AND A NUMBER OF ANALOG VIDEO ENCODER CHIPS.FPGA = XILINX XCV4FX40 AND XCV4LX25. THE ANALOG CIPS WERE NOT DAMAGED. BOTH FPGAS WERE TOAST. NO VISIBLE DAMAGE WAS PRESENT. WHAT COULD CAUSE THIS TO HAPPEN? THE DEVICES ARE CURRENT LIMITED AND HAVE THERMAL SHUT DOWN. I'M LOOKING FOR POSSIBLE CAUSE. IE.. TO HIGH INPUT VOLTAGE, OVER CURRENT OUTPUT, VOLTAGE SPIKE ON INPUT OR OUTPUT.
INPUT VOLTAGE IS 5VDC FROM VME POWER SUPPLY. REGULATORS ARE TURNED ON SEQUENCIALY WITH POWER GOOD SIGNAL FROM PREVIOUS REG. THE ONLY THING COMMON TO ALL 6 BOARDS IS 5 VDC INPUT FROM VME BUT THIS IS PROVIDED TO A HOTSWAP CONTROLLER ON EACH BOARD THAT THEN SUPPLIES THE LDOS. ALL BOARDS HAVE COMMON GND.
