Patent ID: 7514951
Filing Date: 2009-04-07
Classification: H03K

Abstract:
1. A negative voltage noise-free circuit for multi-functional pads comprising: an input/output (I/O) pad of an integrated circuit chip, a normal mode internal node, which connects to normal mode circuitry, a test mode internal node, which connects to test mode circuitry, a first transfer device switch which connects said input/output (I/O) pad to an intermediate internal node, a second transfer device switch which connects said intermediate internal node to said test mode internal node, a third transfer device switch which connects said input/output (I/O) pad to said normal mode internal node, a pull-up load device, which is connected to a power supply voltage and to said intermediate internal node, and a test mode signal which connects to a gate of said first transfer device switch, to a gate of said second transfer device switch, and to an inverter which inverts said test mode signal to produce a normal mode signal.