Can an IR2104 control more than a dozen MOSFETs at the same time?

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just_solike7
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First reply posted First question asked Welcome!

Now,I want to use IR2104 to control the full-bridge inverter circuit to realize the conversion of DC to AC. The normal way of use is that two ICs control four MOSFETs to drive a full-bridge circuit, but I need more at the same time.

Can I use two ICs to drive more than one full-bridge inverter circuit? That is, two ICs are used to control more than four MOSFETs, such as a dozen or tow dozen.

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Abhilash_P
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50 likes received 500 replies posted 250 solutions authored

Hi,

      The MOSFET 2N7002 has a gate charge of about 2nc @ Vgs =10V. Considering that you are driving 60MOSFEts in parallel, the total gate charge comes to be around 120nC.

As required, the desired turn-on/off of the FETs is 500ns, you will require a driver capable of sourcing/sinking          Ipk = dQ/dt = 120nC / 500ns where Ipk = 0.24A.

As mentioned, each channel of IR2104 IC can source/sink peak currents up to 130mA.

Hence according to the calculation, the driver is not capable to drive 60 MOSFETs' in parallel with the desired conditions. For driving 60 MOSFETs' with the desired turn-on/off of the FETs, you can parallel the channels to increase the drive current of the gate driver.

Regards,
Abhilash p

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just_solike7
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First reply posted First question asked Welcome!

Any infineon application engineer comes to response this question? it is urgent to me .

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Abhilash_P
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50 likes received 500 replies posted 250 solutions authored

Hi,

  Thank you for posting on the Infineon community.

        For driving parallel MOSFETs with a single driver, you need to consider the combined gate charge of the MOSFETs which are being used.
        The drive current of the Gate driver IR2104 is around 130mA. If the drive current capability of the gate driver is less, then the turn ON /turn OFF times are affected. You can use a higher drive current capable device for the required application.
        Before using the gate driver, you can simulate based on the required condition and check how fast the MOSFET is being switched. The gate drive current and the switching times are related. Hence this has to be taken into account. Keeping this in mind, you need to calculate the rise times of your MOSFETs' ( parallel MOSFETs') and match with the drive currents. 
      One more thing to consider while driving parallel MOSFETs' is that  you have to keep the trace lengths between the parallel MOSFETs and the driver as close to the same as possible to minimize timing differences so that all the FETs feel the load at the same time.
     When paralleling MOSFETs, the current load will be shared between devices (provided they have the same characteristics and are at the same Tj). There will be some discrepancy due to the gate voltage time offset. The body diodes will also share the load. Please do simulate your condition and check the FOM variations. Please note that Qrr is very dependent on Id and di/dt, and the latter will be dictated by the stray inductance of your board mainly. I suggest you make a simulation with your specific parameters in order to have the best approximation possible.

     Please do share the Mosfet parts numbers and the number of MOSFETs being used for checking the feasibility of this use case. 

 

Regards,
Abhilash P

 

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Hi, Abhilash.

Thank for your reply. 

I will pay attention about the trace lengths between the parallel MOSFETs. 

I use two ICs to try to control four MOSFETs(normal way of using ) to observe their turn ON and turn OFF time, the turn ON time about 1 us, the turn ON time about 500 ns.

Even if I increase to eight MOSFETs, its opening time has not changed significantly. Is this due to the problem of simulation software? Or is the drive current large enough?

I want to use two ICs to control 60 MOSFETs. Because the single that their need are the same. The model of MOSFET is 2N7002, SOT-23. Can it work normally? Or 30 MOSFETs?

 

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Abhilash_P
Moderator
Moderator
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50 likes received 500 replies posted 250 solutions authored

Hi,

      The MOSFET 2N7002 has a gate charge of about 2nc @ Vgs =10V. Considering that you are driving 60MOSFEts in parallel, the total gate charge comes to be around 120nC.

As required, the desired turn-on/off of the FETs is 500ns, you will require a driver capable of sourcing/sinking          Ipk = dQ/dt = 120nC / 500ns where Ipk = 0.24A.

As mentioned, each channel of IR2104 IC can source/sink peak currents up to 130mA.

Hence according to the calculation, the driver is not capable to drive 60 MOSFETs' in parallel with the desired conditions. For driving 60 MOSFETs' with the desired turn-on/off of the FETs, you can parallel the channels to increase the drive current of the gate driver.

Regards,
Abhilash p

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