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LT8390 buck-boost mode switch

Category: Hardware
Product Number: LT8390

Hello,

I choose LT8390 for my new design, below are the Specs:

Input: 18 to 28V (24V typically)

output: 0 to 30V

current: 14A

purpose: Charge the supercapacitor(The supercapacitor will charge from 0V  to  30V)

In my opinion, when be charging, the supercapacitor will keep the 14A current constant although the LT8390 will go through a buck-boost mode switch, which from buck mode to boost mode.

Here are some of the things that happened while I was debugging:

1. When the voltage of supercapacitor below 18V : the charging current is 14A constant.

2. When the voltage of supercapacitor is about 18 V: the charging current is suddenly drops to about 4A.

3. When the voltage of supercapacitor is about 24 V: the charging current drops to about 2A.

Here are some questions:

1. If LT8390 is suitable for my purpose(charge the supercapacitor)?

2. Are there any mistake I might make in my design?

3. What should I pay attention to in my design for charging the supercapacitor?