How did framers put limits on democracy?

The framers limited democracy in the US by developing a government structure that isn't a pure democracy. Instead, the framers developed a democratic republic. In a democratic republic, elected officials make governing decisions rather than the masses. In creating this type of government, the framers hoped to streamline the government's decision-making process and create a system that would be less negatively affected by low voter turn-out and tensions between the classes. 
Another way in which the framers limited democracy was by incorporating a central government. By including a central government, the framers made it so the states had to work together rather than compete with one another for commerce and power. The central government is divided into three branches that each have checks and balances on one another's power. These checks and balances make sure that the representatives do not develop too much power. It also protects the minority from the majority votes by making sure that those in power are governed by the laws of the land.