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Smart Power Switches Forum Discussions

jRn
Level 1
First question asked Welcome!
Level 1

Hello community,

 

I have a question about the BS50085 high side switch.

Why do I need an additional Z-diode Vzl / Vzb for reverse battery protection?

jRn_0-1640782045417.png

 

If Vbb disconnected with an inductive load, there should be an freewheeling diode. But why the Z-diode ?

 

Is there no reverse battery protection if I am adding this:

jRn_1-1640782045423.png

Thanks in advance.

Best regards,

Juergen

 

 

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

Hello jRn,

Thank you for posting on Infineon Community.

Regarding the questions:

1.Why do I need an additional Z-diode Vzl / Vzb for reverse battery protection?

>>>When a reverse voltage is applied across a normal diode and a Z-diode , it is likely to happen that a normal diode would not survive the avalanche breakdown and may get permanently destroyed due to the sudden spike of current. But a Zener diode is designed to operate under this condition, hence providing reverse battery protection.

2. Using a power transistor(N-channel or P-channel MOSFET) is an alternative way of reverse battery protection.
You can also refer to this document for better understanding :
https://www.infineon.com/dgdl/Reverse-Batery-Protection 

Best Regards,
Anshika    

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

Hello jRn,

Thank you for posting on Infineon Community.

Regarding the questions:

1.Why do I need an additional Z-diode Vzl / Vzb for reverse battery protection?

>>>When a reverse voltage is applied across a normal diode and a Z-diode , it is likely to happen that a normal diode would not survive the avalanche breakdown and may get permanently destroyed due to the sudden spike of current. But a Zener diode is designed to operate under this condition, hence providing reverse battery protection.

2. Using a power transistor(N-channel or P-channel MOSFET) is an alternative way of reverse battery protection.
You can also refer to this document for better understanding :
https://www.infineon.com/dgdl/Reverse-Batery-Protection 

Best Regards,
Anshika    

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