Internal protection circuit and method for on chip programmable poly fuses

摘要

An integrated circuit (10) having at least one programmable fuse (F1) and ESD circuitry (MN3, MN1) preventing the fuse (F1) from being unintentionally blown when a voltage transient exists on a main voltage potential (Vmain). The ESD circuitry preferably comprises of MOSFET switches which are coupled to turn on quicker than a main fuse programming switch (MNmain) due to the voltage transient, thereby insuring that the main switch remains off during the voltage transient to prevent the unintentional blowing of the fuse F1. The circuit is well suited for programmable logic device (PLDs), allowing for read voltages as low as 6 volts, and allowing for programming voltages as high as 40 volts. <IMAGE>