My company (SME size) need 35 % cash deposit coverage to arrange revolving credit line. Maybe that’s answer on your question, it’s depending on Company’s ability to borrowing, credit risk appraisal, size of company, geo location etc.
Collateral cash deposit is an interest bearing as well.
I don’t think there is such an category in credit enhancement, either internal (waterfall structure, over collateralization, yield-spread ) or external ( bank guaranteed, surety bond, letter of credit, cash collateral account).
I’m working in the bank as the teller. I did see an similar example of cash collateral account in retail banking.
If you keep pay the minimum payment of the revolving loan( credit card payment or personal line of credit at each statement period), you could keep borrowing from your revolving loan until you reach the credit limit.