LT8611 damaged with absent input voltage

Question

Hello, 
 
 we are using the LT8611 for charging a 12V lead acid battery. 
 When the 24V input voltage is removed the LT8611 will be destroyed. 
 We added a diode like the recommendation from the LT8611 datasheet (page 18, figure 5) but this didn&acute;t prevent the fault of the LT8611 when the input voltage is absent. 
 
 The schematic is attached below. 
 
 Any help is greatly appreciated, 
 
 Thomas 
 
 PDF

Andrew S. · Answer

Hi Thomas, 
 Thanks for use of LT8611 and the information. 
 One of the possible sources, which causes the damage in battery charging application, comes from the reserve current, suddenly stepping up the voltage stress and exceeding the allowed max voltages on some pins. 
 The simple solution to this problem is to add a forward-biased diode between the output of the part and the battery. 
 If additional information is needed, please let me know. 
 Best regards, 
 Chuan

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LT8611 damaged with absent input voltage

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