- 专利标题: Programmable logic device input/output circuit configurable as reference voltage input circuit
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申请号: US09846409申请日: 2001-05-01
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公开(公告)号: US06335636B1公开(公告)日: 2002-01-01
- 发明人: Wayne Yeung , Chiakang Sung , Myron W. Wong , Khai Nguyen , Bonnie I. Wang , Xiaobao Wang , Joseph Huang , Im Whan Kim
- 申请人: Wayne Yeung , Chiakang Sung , Myron W. Wong , Khai Nguyen , Bonnie I. Wang , Xiaobao Wang , Joseph Huang , Im Whan Kim
- 主分类号: H01L2500
- IPC分类号: H01L2500
摘要:
A programmable input/output circuit for a programmable logic device input/output pin can be configured in a standard I/O mode, or in a reference voltage mode. The circuit includes a tristatable, but otherwise standard I/O buffer as well as a reference voltage clamp circuit. In reference voltage mode, the I/O circuit is tristated, and the reference voltage clamp circuit passes a reference voltage from the I/O pin to a reference voltage bus. In standard I/O mode, the I/O buffer is operational. The reference voltage clamp circuit isolates the I/O pin from the reference voltage bus and may include undervoltage and overvoltage protection to prevent disturbance of the reference voltage bus by an out-of-range I/O signal.