Current sensing circuit for use with a current controlling device in a power delivery circuit

A power delivery circuit for supplying load current to a load, comprising:

• a power node for connection to a source of electrical power;
• a load node for connection to a load;
• a high potential current path for supplying electrical current from the power node to the load node and including a current switch whose switching state is controlled by a control signal on an associated control terminal;
• said current switch having first and second main terminals, a first auxiliary terminal which produces a current which is a predetermined fraction of the total current in the high potential current path, and a second auxiliary terminal connected to one of the main terminals of the current switch;
• and
• a current detection circuit for detecting the current level in the high potential current path;
• the current detection circuit comprising:
• a first branch connected between one of said first and second auxiliary terminals and a reference potential and a second branch connected between the other of said first and second auxiliary terminals and the reference potential,
• said first branch having a first semiconductor device and said second branch having a second semiconductor device, said first semiconductor device being a bias signal-controlled transimpedance device and said second branch providing a bias signal for said first semiconductor device,
• said first branch having a third semiconductor device and said second branch having a fourth semiconductor device,
• said third and fourth semiconductor devices being configured to provide a predetermined current ratio in said first and second branches, and
• an output node for providing a signal approximately proportional to the load current.