Hi
I have a TX7316EVM development board:
http://www.ti.com/lit/ug/sbou224a/sbou224a.pdf
It needs 3 bench power supplies to operate which can deliever +-5VDC(.2A) on J3 connector, +-50VDC(.03A) on J1 connector and +-100VDC(.03A) on J2 connector.
When testing, the problem arose when voltage +5V DC on J3 connector fell down to around 0.6V and the bench power supply LED changed from CV(constant voltage as it should be) to CC(Constant Current). I guess it might have happened because of short circuit which i could not see at the time when it happened since so many wires were tightly packed. So i removed the R16 resistor(see User manual) and applied +5VDC right into the inputs of DC DC converters(U1,U2,U3 for making 3V3, 1V8, 2V5) i.e. i provided V_+5V (Page 45) and thus the VDDP_LP5 voltage was no longer in the picture(this goes to the TX7316 IC power) as i removed R16. But this 5V after R16 (V_+5V) also drops to 2.45V which i thought should have been 5V. The LEDS which were connected to U1,U2,U3 were ON at least but the PSU was still showing 2.45V and .2A at CC.
And then i connected again 0R(R16) and the LEDs went OFF and voltage decreased again to 0.6V, , 0.2A at CC. So is this because the TX7316 is not working now and the current goes directly into this IC.
As long as visual inspection of the board, i cannot see anything burnt or strange. Also i have removed the two capacitors(c9,c10) and a zener diode(d7) at the input of J3 Connector, but results were same.
The -5VDC is working fine.