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MOSFET (Si/SiC) Forum Discussions

Huffy
Level 1
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Ref: IPB014N06N

Does anyone have suggestions on using the above mosfet for current sharing in a H-bridge configuration? Each switch is composed of 10 mosfets in parallel for a total current load of 600A.  I am having issues with one of the mosfets overheating due to unbalanced current sharing.  Does anyone have suggestions on PCB layout and long-term reliability of this approach for current sharing?

Thanks

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G_Anshika
Moderator
Moderator 100 replies posted 50 solutions authored 100 sign-ins
Moderator

Hello Huffy,

Thank you for posting on Infineon Community.

1. Can you please let me know what your high-power application is?

2. H-Bridge configurations are used when there is a requirement of controlling the current, and its direction.

 I. For unequal sharing of current: 
--> Even if the two power devices are on the same chip in a monolithic structure with nearly identical on-resistance RDS(on) and transconductance (gm), several other characteristics can result in unequal sharing of current in a dynamic state between the MOSFETs. While the devices operate in parallel with the gates connected to the PWM signal with very low duty cycles, the steady-state current sharing among the devices, which is based on RDS(on) variation concerning temperature variation, may not hold true. 
This could be due to parasitic capacitors, resistors, and delay paths in the circuit and on the PC board, depending on the device and PC board arrangement. 

Try to layout the circuit symmetrically, which will alleviate the issue of unequal dynamic current sharing, by matching the parasitic capacitance, inductance, and resistance. 

ii. Switching losses account for a significant portion of total power dissipation, resulting in a rise in           temperature. Please make sure that the losses are within the limits to prevent the overheating.
Consider adding an external heat sink if the heat sinking capacity in the system is insufficient to transfer the heat to the atmosphere, keeping the device below the thermal shutdown temperature threshold.

Additionally, thermal vias, external heat sinks, adding copper, more layers in the PCB, and a symmetrical circuit layout can be helpful in improving the system's heat sinking capability.

Regards,
Anshika

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G_Anshika
Moderator
Moderator 100 replies posted 50 solutions authored 100 sign-ins
Moderator

Hello Huffy,

Thank you for posting on Infineon Community.

1. Can you please let me know what your high-power application is?

2. H-Bridge configurations are used when there is a requirement of controlling the current, and its direction.

 I. For unequal sharing of current: 
--> Even if the two power devices are on the same chip in a monolithic structure with nearly identical on-resistance RDS(on) and transconductance (gm), several other characteristics can result in unequal sharing of current in a dynamic state between the MOSFETs. While the devices operate in parallel with the gates connected to the PWM signal with very low duty cycles, the steady-state current sharing among the devices, which is based on RDS(on) variation concerning temperature variation, may not hold true. 
This could be due to parasitic capacitors, resistors, and delay paths in the circuit and on the PC board, depending on the device and PC board arrangement. 

Try to layout the circuit symmetrically, which will alleviate the issue of unequal dynamic current sharing, by matching the parasitic capacitance, inductance, and resistance. 

ii. Switching losses account for a significant portion of total power dissipation, resulting in a rise in           temperature. Please make sure that the losses are within the limits to prevent the overheating.
Consider adding an external heat sink if the heat sinking capacity in the system is insufficient to transfer the heat to the atmosphere, keeping the device below the thermal shutdown temperature threshold.

Additionally, thermal vias, external heat sinks, adding copper, more layers in the PCB, and a symmetrical circuit layout can be helpful in improving the system's heat sinking capability.

Regards,
Anshika

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