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TPS2393 Problem

Other Parts Discussed in Thread: TPS2393

Team,

I just picked this account up and they already designed in the TPS2393 and is having some problems.  Attached are the schematics and come infor below.  Does this device even work at +48V?

---------------------------------------- From customer

We are using TPS2393 in our board and the schematic page is attached. For some reason this circuit is not working. We are connecting 48V (+) to 48V_EMI_P and GND to 48V_EMI_N. Do we need any changes for +48V system.

 

Here are the voltage levels at different pins

 

1 (INSA) = low

7 (INSB) = low

13 (/FAULT) = 48V

14 (EN) = 1.4V

28 (GATE) = low

40 (/PG) = high

43 (OVLO) = low (.9V)

44 (UVLO) = 2.1V

 

PAN_tps2393_circuit.pdf
  • The schematic is right out of the datasheet so that should be ok.

    The pin voltages are helpful. The 1.4 volts for the EN is a little low. The datasheet says it could be as high as 1.5V to enable. The datasheet has a 5.6V Zener.

    The Ramp capacitor is small at 390pF. I'm sure of the load but I see a couple og large capacitors. Increase the Ramp capacitors, try around .01uF. You can adjust once you get running.

    The Fault capacitor looks large but that's no issue to you yet.

    If it is still not working, get some scope photos at power up showing input voltage, output voltage, Gate, and IRAMP