Personal HELOC Draw-Business Repayment Need Formal Agreement?

[Beckie Trudeau]

I just took a draw from my primary residence's HELOC and immediately deposited the funds directly into my business LLC checking account so that I could make a large contractor payment. Now I need to start monthly repayments on the HELOC. Today I paid the first payment from my business checking account. I know that I don't want to mix personal with business finances. Can I set up some sort of agreement or promissory note that formalizes this properly? Other ideas on how to account for the funds and repayment?