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ISO5852

Mikhail Monakhov
Prodigy 10 points
Other Parts Discussed in Thread: ISO5852SEVM, ISO5852S, TIDA-00195

Hi,

I have a task to develop a multi-channel power controller. It have to control temperature in the IR oven. The source of the control signal is a controller and the driver - ISO5852, a control signal for the driver - PWM 1 kHz. The driver will drive a powerful IGBT transistor. I assembled a prototype according to the scheme ISO5852SEVM. As the power supply, I installed a diode bridge on the line 230V AC. To supply driver 16 VDC unipolar power supply has been used.
When I used as a load 230V 100W incandescent lamp it works fine with IGBT and MOSFET transistors. When I increased the load, using the IR lamp 1000W 230V, ISO5852 protected MOSFET transistor during the cold start lamp when passing a very high current. Then I set the IGBT transistor instead MOSFET and the driver was not defend the transistor.
A cold start lamp is similar to the short-circuit mode, but the driver still had to protect the transistor. MOSFET transistor I used IRFP350, IGBT - STGW40M120DF3.
Please tell me where I made a mistake. Why the driver does not protect the IGBT transistor?
Is there any solution, how can we solve the cold start problem for infrared lamps?

  • 0
    TI__Genius 12380 points
    Hi Mikhail,

    Welcome to the E2E forums!

    Sorry for the delay, but we are coming back from US holiday. This question for an ISO5852 belongs under the Industrial Interface forum. I will move this thread accordingly so that the appropriate team may assist you.

    Thanks!
    Alex
  • 0
    TI__Intellectual 1665 points

    Hi Mikhail,

    The operation of the short circuit protection circuit inside ISO5852S is based on measuring the VCE/VDS when the power device is ON. A voltage comparator is used to trigger the short circuit fault protection. The threshold voltage is 9.0V, which is translated into different short circuit protection currents for IGBT and MOSFET based on the PNs you provided. The protection current is around 30A for MOSFET while more than 150A for the IGBT. You can add more DESAT diodes in series or increase the DESAT resistance if you want to reduce the protection circuit for the IGBT. 

    Please let me know if you have any questions. 

    With Regards,

    Xiong 

  • 0 in reply to Xiong Li
    TI__Expert 4250 points
    Hi Xiong,

    If I want to have a lower short/over current protection for IGBT or MSOFET. Then multi-stage diodes are used to achieve lower Vce-fault = 9V-n*Vf(This is the equation used in TIDA-00195.)? Is there any guide for forwarding voltage selection for diode or other ways to adjust the Vdesat voltage?

    Thanks a lot.

    Zhou
  • 0 in reply to Zhou Fang67
    TI__Intellectual 1665 points

    Hi Zhou,

    The DESAT protection threshold value is guarded by the equation VCESAT = 9V - n*VF - ICHG*RDESAT

    Series diodes can be used for loose tune while DESAT resistor can be used for fine tune of the protection threshold. 

    With Regards,

    Xiong 

  • 0 in reply to Xiong Li
    TI__Expert 4250 points
    Hi Xiong,

    TIDA-00195 uses diode GL41Y-E3/96, it gives 0.8V voltage drop with 50mA forwarding current. In our ISO5852 datasheet, DESAT pin charging current is around 0.5mA. The forwarding voltage drop is proportional to the forwarding current. In other word, the forwarding voltage for diode @0.5mA is very low, VF is very low. then it needs a lot diode to be serial. Is it right?

    We need VCESAT =4V or 5V, what is the best way to do it?

    Thanks a lot.
    Zhou
  • 0 in reply to Zhou Fang67
    TI__Intellectual 1665 points
    Hi Zhou,

    There is a threshold voltage to turn-on a diode. The diode is on when there is a 0.5mA current flowing through it. You can determine the number of series diodes with VF being equal to the turn-on threshold voltage. Then, you can fine tune the VDESAT voltage with the DESAT resistance.

    With Regards,
    Xiong