uint public minBorrowUSD;

function setMinBorrowUSD(uint _value) external onlyOwner {
  minBorrowUSD = _value;
}
function _checkBorrowLimits(address _token, address _account) internal view {
  ...
  require(accountBorrowUSD >= controller.minBorrowUSD(), "LendingPair: borrow amount below minimum");
