Hysteretic fuse control circuit with serial interface fusing

Abstract

A fuse status detection and serial interface programming circuit which provides a current-free method of detecting a fused/non-fused state of a fuse, and which also prevents filament regrowth. The circuit employs an output inverter to monitor the status of the fuse, and switching transistors to initially blow the fuse, and automatically reblow the fuse if filament regrowth appears.

What is claimed is:  
     
         1 . An electrically blowable element progranuning and status detection circuit, comprising: 
 a electrically blowable element; and    a feedback control circuit for applying current to said electrically blowable element, and holding said electrically blowable element in a blown state.    
     
     
         2 . The integrated circuit of    claim 1   , wherein said electrically blowable element is a polysilicon fuse, metal fuse, or a zener diode.  
     
     
         3 . The integrated circuit of    claim 1   , wherein said feedback control circuit operates in a hysteretic fashion by not returning to its preblown state.  
     
     
         4 . The integrated circuit of    claim 1   , wherein said feedback control circuit comprises at least first and second transistors for applying said current to said electrically blowable element, and an inverter circuit for controlling said first transistor, said first transistor being a PMOS transistor, and said second transistor being an NMOS transistor.  
     
     
         5 . The integrated circuit of    claim 1   , wherein said feedback control circuit comprises at least first and second transistors for applying said current to said electrically blowable element, and wherein both said first and second transistors are NMOS transistors.  
     
     
         6 . The integrated circuit of    claim 1   , wherein, in said feedback control circuit, a diode is interposed in the current path from a first transistor to said electrically blowable element, said first transistor being an PMOS transistor.  
     
     
         7 . The integrated circuit of    claim 1   , wherein said feedback control circuit uses two independent supply voltages.  
     
     
         8 . An electrically blowable element programming and status detection circuit, comprising: 
 a electrically blowable element; and    a feedback control circuit for applying current to said electrically blowable element, and comprising 
 at least first and second active elements operatively connected to said electrically blowable element to apply current to said electrically blowable element; and  
 an inverter circuit connected to provide feedback to said first active element, and comprising an output for status detection of said electrically blowable element;  
   wherein said detection circuit is substantially current-free until filament regrowth occurs, at which time said feedback control circuit automatically re-blows said electrically blowable element.    
     
     
         9 . The integrated circuit of    claim 8   , wherein said electrically blowable element is a polysilicon fuse, metal fuse, or a zener diode.  
     
     
         10 . The integrated circuit of    claim 8   , wherein said feedback control circuit operates in a hysteretic fashion by not returning to its preblown state.  
     
     
         11 . The integrated circuit of    claim 8   , wherein said first active element is a PMOS transistor, and said second active element is an NMOS transistor.  
     
     
         12 . The integrated circuit of    claim 1   , wherein said first and second active elements are NMOS transistors.  
     
     
         13 . The integrated circuit of    claim 8   , wherein both said first and second transistors are PMOS transistors.  
     
     
         14 . The integrated circuit of    claim 8   , wherein, in said feedback control circuit, a diode is placed in the current path from said first active element to said electrically blowable element, said first active element being an PMOS transistor.  
     
     
         15 . The integrated circuit of    claim 8   , wherein said feedback control circuit uses two independent supply voltages.  
     
     
         16 . An integrated circuit for programming and detecting the status of an electrically blowable element while the electrically blowable element is encased within the packaging, comprising: 
 at least one electrically blowable element; and    a feedback control circuit operatively connected to said electrically blowable element to apply current to said electrically blowable element, said feedback control circuit comprising 
 at least one active element operatively connected to said feedback control circuit, said active element connected to provide a serial interface to said feedback control circuit, and for receiving a blow signal.  
   
     
     
         17 . The integrated circuit of    claim 16   , wherein said electrically blowable element is a polysilicon fuse, metal fuse, or a zener diode.  
     
     
         18 . The integrated circuit of    claim 16   , wherein said active element is a NMOS transistor.  
     
     
         19 . The integrated circuit of    claim 16   , wherein said feedback control circuit operates in a hysteretic fashion by not returning to its preblown state.  
     
     
         20 . The integrated circuit of    claim 16   , wherein, in said feedback control circuit, a diode is interposed in the current path from a second active element to said electrically blowable element, said second active element being a PMOS transistor which receives a supply different from a supply voltage of said feedback control circuit.  
     
     
         21 . The integrated circuit of    claim 16   , wherein said feedback control circuit uses two independent supply voltages.  
     
     
         22 . A method for programming and detecting an integrated electrically blowable element, comprising the steps of: 
 (a.) activating a feedback control circuit to apply current to a electrically blowable element; and    (b.) holding said electrically blowable element in a blown state using said feedback control circuit.    
     
     
         23 . The method of    claim 22   , wherein said electrically blowable element is a polysilicon fuse, metal fuse, or a zener diode.  
     
     
         24 . The method of    claim 22   , wherein said feedback control circuit comprises at least first and second transistors for applying said current to said electrically blowable element, and an inverter circuit for controlling said first transistor.  
     
     
         25 . The method of    claim 22   , wherein said feedback control circuit operates in a hysteretic fashion by not returning to its preblown state.  
     
     
         26 . The method of    claim 22   , wherein said feedback control circuit comprises at least first and second transistors for applying said current to said electrically blowable element, said first transistor being a PMOS transistor, and said second transistor being an NMOS transistor.  
     
     
         27 . The method of    claim 22   , wherein, in said feedback control circuit, a diode is interposed in the current path from a first transistor to said electrically blowable element.  
     
     
         28 . The method of    claim 22   , wherein said feedback control circuit uses two independent supply voltages.  
     
     
         29 . An electrically blowable element control and detection method, comprising the steps of: 
 (a.) controlling an electrically blowable element with at least first and second active elements operatively connected to switch current through said electrically blowable element, said current being substantial enough to blow said electrically blowable element;    (b.) automatically re-blowing said electrically blowable element when filament regrowth has occurred; and    (c.) detecting the status of said electrically blowable element.    
     
     
         30 . The method of    claim 29   , wherein said electrically blowable element is a polysilicon fuse, metal fuse, or a zener diode.  
     
     
         31 . The method of    claim 29   , wherein said feedback control circuit comprises at least first and second transistors for applying said current to said electrically blowable element, and an inverter circuit for controlling said first transistor.  
     
     
         32 . The method of    claim 29   , wherein said feedback control circuit operates in a hysteretic fashion by not returning to its preblown state.  
     
     
         33 . The method of    claim 29   , wherein said feedback control circuit comprises at least first and second transistors for applying said current to said electrically blowable element, said first transistor being a PMOS transistor, and said second transistor being an NMOS transistor.  
     
     
         34 . The method of    claim 29   , wherein, in said feedback control circuit, a diode is interposed in the current path from said first active element to said electrically blowable element.  
     
     
         35 . The method of    claim 29   , wherein said feedback control circuit uses two independent supply voltages.  
     
     
         36 . A method for programming and detecting an integrated electrically blowable element while the electrically blowable element is encased within the packaging, comprising the steps of: 
 (a.) providing an electrically blowable element operatively connected serial interface to a feedback control circuit;    (b.) switching current through said electrically blowable element to blow said electrically blowable element with said feedback control circuit, and automatically reapplying said current if filament regrowth appears in said electrically blowable element; and    (c.) detecting the status of said electrically blowable element.    
     
     
         37 . The method of    claim 36   , wherein said electrically blowable element is a polysilicon fuse, metal fuse, or a zener diode.  
     
     
         38 . The method of    claim 36   , wherein said feedback control circuit comprises at least first and second transistors for applying said current to said electrically blowable element, and an inverter circuit for controlling said first transistor.  
     
     
         39 . The method of    claim 36   , wherein said feedback control circuit operates in a hysteretic fashion by not returning to its preblown state.  
     
     
         40 . The method of    claim 36   , wherein said feedback control circuit comprises at least first and second transistors for applying said current to said electrically blowable element, said first transistor being a PMOS transistor, and said second transistor being an NMOS transistor.  
     
     
         41 . The method of    claim 36   , wherein, in said feedback control circuit, a diode is interposed in the current path from a first transistor to said electrically blowable element.  
     
     
         42 . The method of    claim 36   , wherein said feedback control circuit uses two independent supply voltages.