US Patent 7824974 Method for manufacturing a constant current source device

A constant current source device with over current and over voltage protection function can be directly applied to AC power and DC power, and a method for manufacturing the constant current source device is also disclosed. The device includes a silicon substrate (1), an oxide layer (6) formed in front of the silicon substrate (1), a drain metal (2), a source metal (3) and a gate metal (4) located in front of the oxide layer (6), a P+ guard ring (50), an N+ drain region (52) and an N+ source region (53) implanted in the silicon substrate (1), a P+ substrate region (51) located in the N+ source region (53), and an N− channel region (54) connecting the N+ drain region (52) with the N+ source region (53). The drain metal (2) and the source metal (3) are separately connected with the N+ drain region (52), the N+ source region (53) and the P+ substrate region (51). The source metal (3) and the gate metal (4) are electrically connected through a connection metal (7). The invention constant current source device is generally applied to the field of electronic devices.