I am using LT8490 MPPT charger IC for one of my current project.
I would like to protect my board from Reverse Protection.
can you suggest how to protect the MPPT charger IC and board from Reverse protection.
You could have a look at LTC4364 and similar products. I do not have the detailed knowledge about this product line to give detailed advice.
Depending on how your system is set up, there may be a simpler solution. if it does not matter that load Ground and LT8490 Ground are not connected (for example, you are using a solar panel that is floating relative to Ground, and you do not have anything connected to the LT8490) you could simply add an n-Channel MOSFET between charger negative terminal and the battery negative terminal. Drain to battery Minus, Source to charger Minus, Gate to charger Plus. if the charger is off and the battery is connected with the correct polarity, voltage will appear on the output terminals of the charger, which means the charger will start and the MOSFET will turn on. If the battery is connected with the wrong polarity, the gate-source voltage will remain zero and the battery voltage will appear across the MOSFET. but the charger output will remain at zero volts, so it will not start.
This is a very crude reverse protection, and the drawback is that if the battery is first attached with correct polarity so the charger starts and the battery is then removed and attached with the wrong polarity, the charger MAY still be running so the reverse protection will not work. you would need to always stop the charger before removing the battery, which is always a good idea anyways, as there will be flammable gases around the battery when charging, and if you remove the battery connection while charge current is flowing, there will be sparks that can ignite the flammable gases. This would be a concern especially with wet lead acid batteries.
Always include a fuse or circuit breaker in series with the battery cable.
Another simple protection against reverse battery is to add a large Schottky diode across the charger output terminals, on the charger side of the fuse, and hope that if the battery is connected in reverse, the Schottky diode will survive the shortcircuit current. This kind of protection is not very safe, it does not guarantee there is no damage to the LT8490 circuitry, and the diode must be large. but it may work in some cases if the battery is inserted backwards only very rarely.
Hi Tage,Thanks for your valuable inputs !!!If I used N- Channel MOSFET as reverse polarity protection , which you suggested way (Drain to battery Minus, Source to charger Minus, Gate to charger Plus ) through N-Channel MOSFET.If I connected right polarity from DC - input , (charger minus and battery minus got connected) the circuit works fine . If I connected reverse polarity from DC- input , (charger minus and battery minus got connected ) through body diode of MOSFET and will burn the MOSFET and other circuit get damage.
In my application, Solar pannel input to the charger IC (LT8490) , Lead-acid battery Connected output to the charger IC. The charged battery output is given to Buck Boost regualtor to get constant output voltage and goes to the entire board.
If the charger cirucit it turned on I won't remove battery for any case, If needed I will switched off the charger circuit and reconnect the battery.
If I connect the Lead acid battery in reverse poalrity , I want to protect the charger IC (LT8490) and other circuit of board.
Thanks and Regards,Mohamed Sidiq.H
I am not sure I understand your comment, it would be easier to see a schematic or block diagram of the system.
The simple n-ch MOSFET circuit will not work so well if you cannot allow the LT8490 ground to be different than load ground. And it will not protect your load against reverse battery, you may have to look for a hot-swap circuit or a more elaborate circuit. I don't think I can help you with the design of the system. I am more focused on questions directly related to the LT8490.
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