I recently updated a circuit to control the magnitude and direction of a solenoid using 4 MOSFETs and an Arduino. The original was designed by someone else, prototyped, and used with 12 V and about 1A successfully. My upgrade now uses up to 48V and 6A since it is used with different solenoids which require higher power. I changed necessary resistances and components to be able to handle the higher power and made sure that the PCBs were able to handle the power as well.
We are now seeing problems where the MOSFETs will overheat and short (not sure in what order) when used higher than about 3A. Any idea of why this could be? I have been reviewing this for two weeks with no success.
I attached the schematic and datasheets. Inputs 1 and 2 are PWM signals (5V max) attached to the NPN transistors to control how strong the current will be through the P-Type MOSFETs. Inputs 3 and 4 are logic on/off signals (0V/5V) connected directly to the N-Type MOSFETs to allow or stop flow. When one set of diagonal MOSFETs (left P and right N) are open, the flow through the 8 ohm solenoid is positive and negative when the other diagonal set is open. I am fairly certain that both sets of MOSFETs are being fed full gate-source voltage.
Additional questions include:
-Are the diodes across the MOSFETs redundant if the MOSFETs have a diode rated for the voltage/current
-Are the N-Type MOSFETs necessary. They are close to ground and overheat more often than the P-Type.
We are now seeing problems where the MOSFETs will overheat and short (not sure in what order) when used higher than about 3A. Any idea of why this could be? I have been reviewing this for two weeks with no success.
I attached the schematic and datasheets. Inputs 1 and 2 are PWM signals (5V max) attached to the NPN transistors to control how strong the current will be through the P-Type MOSFETs. Inputs 3 and 4 are logic on/off signals (0V/5V) connected directly to the N-Type MOSFETs to allow or stop flow. When one set of diagonal MOSFETs (left P and right N) are open, the flow through the 8 ohm solenoid is positive and negative when the other diagonal set is open. I am fairly certain that both sets of MOSFETs are being fed full gate-source voltage.
Additional questions include:
-Are the diodes across the MOSFETs redundant if the MOSFETs have a diode rated for the voltage/current
-Are the N-Type MOSFETs necessary. They are close to ground and overheat more often than the P-Type.
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