Antifuse-controlled analogue circuit trimming with security locking antifuse

摘要

A trimming circuit for an analogue IC includes a number of antifuses 24.1 to 24.N controlling switching MOS transistors P1.1 and N1.1 operating to alter resistances in the IC. Trial trimming data is read into the circuit serially 12 to control the switches, and when a suitable trimming data set is established the antifuses 24.1 to 24.N are blown. The security antifuse 15 is then blown to prevent any accidental further trimming.