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Smart Power Switches Forum Discussions

User20067
Level 1
First solution authored First reply posted First question asked
Level 1
Hi,

I have a circuit with a AUIPS7221R High frequency Protected High Side Switch used to drive a solenoid with PWM control.

I selected this switch as it was indicated to allow high frequency PWM so I can drive the solenoid with 15kHz to avoid the audible frequencies.

The solenoid is 5.32 ohm and is driven from a 24V SMPS with 100ms at 60% PWM and then while idle at 20% PWM.

There is a snubber diode across the solenoid.

Other than that, the setup is exactly as per the datasheet circuit and there is a fair amount of copper around the device on the PCB (top and bottom).

The problem I am having is that after a few uses of operating the solenoid a couple of times the switch goes somewhat short circuit in that when the 24V power is switched on and the gate drive is still off, the switch already connects power to the solenoid and the solenoid attracts (with sometimes disastrous and smoking results)

I now already have a stack of 7 blown up PCB's on my desk and I have no idea as to what is going on.

What can cause this 'intelligent' and 'protected' switch get damaged so easily or what could I be doing wrong?
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User20067
Level 1
First solution authored First reply posted First question asked
Level 1
Turns out I was not using a Schottky diode on the solenoid.

The regular diode has a recovery time in the order of 1.5us. With the fast switching available from the AUIPS7221, the diode effectively represented a short to ground for a few micro seconds every time the AUIPS7221 was turned on causing high current peaks.

A Schottky diode with a recovery of some 10ns prevents this short and prevents the damage.

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User20067
Level 1
First solution authored First reply posted First question asked
Level 1
Turns out I was not using a Schottky diode on the solenoid.

The regular diode has a recovery time in the order of 1.5us. With the fast switching available from the AUIPS7221, the diode effectively represented a short to ground for a few micro seconds every time the AUIPS7221 was turned on causing high current peaks.

A Schottky diode with a recovery of some 10ns prevents this short and prevents the damage.
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G_Anshika
Moderator
Moderator 100 replies posted 50 solutions authored 100 sign-ins
Moderator

Hello,
Thank you for posting on Infineon Community.

Thanks and Regards,
Anshika


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