Power amplifier with current limiter circuit

Claim 1

A power amplifier for controlling the current flow through a load, comprising: a plurality of switching elements connected in bridge fashion with said load and a predetermined power source for coupling the load across alternate output terminals of said power source in accordance with the levels of a pluraltiy of control signals respectively applied to said plurality of switching elements; generating means responsive to an error signal for generating said control signals; coupling means capable when enabled of coupling each of said control signals from said generating means to the respective switching element for controlling same; sensing means coupled to said load for generating an actual current signal indicative of the actual level of current flow through said load; current limiter means coupled to said sensing means and including a first comparator having a first input for receiving a first reference signal indicative of an upper level limit of current flow through said load, a second input for receiving said actual current signal, and an output for developing an upper limit disable signal when said actual current signal exceeds said first reference signal; a second comparator having a first input for receiving said actual current signal, a second input for receiving a second reference signal indicative of a lower level limit of current flow through said load, and an ouput for developing a lower limit disable signal when said second reference signal exceeds said actual current signal; and a gate coupled to the outputs of said first and second comparators for developing said current disable signal when either or both of said upper and lower limit disable signals are true; and disable means coupled to said current limiter means and responsive to said current disable signal for virtually instantaneously disabling said coupling means whereby further current flow through said load is virtually instantaneously inhibited.