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LT3094 unknown output

Hi,

I'm currently having an output issue that I hope someone can shed some light on.

I have the LT3094 connected with the following:

GND: pins 6 (ILIM), 9 (GND)
VIN (@ -15V): pins 1 (IN), 2 (IN), 3 (EN/UV), 5 (PGFB), and 13 (Exposed Pad)
PG: NC (floating)
VOUT: pins 10, 11, 12
VIOC: NC (floating)
SET: pin 8 is set to 130.5kohm (for -13.5V Vout)

** all recommended caps are also in place **

Please see the LTSPice picture. According to ltspice output as well as the datasheet pin definitions and connection info, I was expecting to see -13.5V on my lab circuit.

However, what I'm measuring is -5.999V (-6V) at Vout(?).

There is no overheating of the IC - my only guess/possibility is that the thermal shutdown is tripping.

Suggestions?

Thank you.
RW.

  • Hi,

    Can you show the waveform you're getting on the output with -6V to see and determine if it really is a thermal shutdown or for any possible reasons. It will be easier to decipher if you can provide us with waveform.
    One way to also check if there is a fault on your circuit is by putting a pullup resistor on your PG pin, if fault is detected PG should be low.

    thanks!