Texas Instruments Incorporated
OPERATIONAL AMPLIFIER WITH INDIRECT CURRENT FEEDBACK CURRENT LIMITER

Abstract:

A circuit includes an operational amplifier having: a positive input; a negative input; an operational amplifier output; a differential front end; a positive channel (PCH) input stage; a negative channel (NCH) input stage; and an output stage. The operational amplifier also includes a current limit circuit coupled to an output of the output stage and including: an output current sense voltage circuit having an output configured to provide an output current sense voltage; an indirect current feedback circuit coupled to the output of the output current sense voltage circuit, the indirect current feedback circuit having an output configured to provide an output current feedback sense voltage responsive to the output current sense voltage; and control circuitry coupled to the indirect current feedback circuit and configured vary a resistance between the output stage output and ground responsive to a difference between the output current feedback sense voltage and a reference voltage.