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GPIO and IPM alarm

Meral Özarslan
Prodigy 210 points

Hello

I am implenting a three phase inverter. I am using IPM (Intelligent power module) for this purpose.

I designed an optocupler circuit to isolate the IPM and ezdsp 320f2812 kit. There is an alarm output on IPM for warning the under voltage, overvoltage and high temperature. I want to take this alarm information into DSP.  The diode side voltage of the optocupler(VCC_IPM)  is from  IPM and for the transistor side voltage of the optocoupler I designed a 3.3 V output voltage regulator (ALM_3.3V and ALMGND). 

I want to ask these:

1 - Will I use GPIO to take this alarm information into DSP?

2- If I use this pin or other, must I conncet the GND of the DSP with tranasistor side GND of optocoupler (ALMGND) ? If I have to do this I will have connected the GND of 15 V supply voltage of 3.3 V regulator with the DSP GND.  Won't be harmful for the DSP connecting the GND of 15 V supply with DSP GND?

I inserted the schematic of the opto circuit . Thank you all.... 

   

  • 0
    TI__Intellectual 800 points

    No sure if you have other more specific concerns, the circuit should work ok.

  • 0
    Intellectual 300 points

    Sorry

    dont you need a current limiting resistor between

    ALM3.3V and collector of optocopler ?

  • 0 in reply to mehmet karakaya
    Prodigy 210 points

    Thank you for your replies.

     

    You are right Mehmet Karakaya. I have forgotten. I corected it thank you very much. I will try to connect the GND of 3.3 V regulstor circuit and the DSP GND. I wish I won't  damage DSP.

  • 0
    Intellectual 340 points

    Hi Meral;

    Your schematic and descriptions seem to be a little bit confusing:

    1. You don't need a separate supply (ALM3.3V/ALMGND) on the DSP side. Simply use DSP_3V3/DSP_GND to power optocoupler's secondary side.
    2. The connection on the  DSP side is wrong... ALM_DSP must be replaced by DSP_3V3; Pin#4 (ALM3.3V) is the pin to be connected to DSP's INT-INPUT; Pin#3 (ALMGND) is to be connected to DSP_GND.
    3. Also on the IPM side, use a series resistor to limit collecter current (ALRM is supposed to be open collector output) either from VCC_IPM to Pin#1 or from pin#2 to ALRM output.The value of this resistor must be in relation to R1's value and opto's current gain.

    Regards

  • 0 in reply to Ibrahim Kolbas
    Prodigy 210 points

    Hi İbrahim

    I thougt to use the DSP 3V3 and DSP GND but I didn't want to use the DSP supply. If I did anything wrong I feared to damage DSP.  I haven't used the supply of DSP before.

    But it will be more  risky if I connect DSP GND with another GND so I will do your suggestion. I did right connectiın and I  attached following. I think it is ok now :)

    I think I should use Interrupt input. 

    On the IPM side there is a series resistor in the IPM (1.5 k) because of this I didn't use a resistor.    Thank you very much. Regards