Patent ID: 7208977
Filing Date: 2007-04-24
Classification: H03K

Abstract:
1. A tristate startup operating mode setting device for providing an electronic circuit unit with a tristate startup operating mode setting function; the tristate startup operating mode setting device comprising: a logic control signal generating module, which is capable of generating a first logic control signal, a second logic control signal, and a third logic control signal in a predetermined pattern of waveform and sequencing; a first switching module, which has a first connecting end, a second connecting end, and a control signal input end, wherein the first connecting end is electrically connected to a pad, and the control signal input end is connected to receive the first logic control signal from the logic control signal generating module, and which operates in such a manner that when the received first logic control signal is at a specified logic state, the first switching module connects the first connecting end to the second connecting end; a first resistive circuit, which has a first connecting end and a second connecting end, wherein the first connecting end is electrically connected to the second connecting end of the first switching module, while the second connecting end is electrically connected to a system voltage source; a second switching module, which has a first connecting end, a second connecting end, and a control signal input end, wherein the first connecting end is electrically connected to both the pad and the first connecting end of the first switching module, and the control signal input end is connected to receive the second logic control signal from the logic control signal generating module, and which operates in such a manner that when the received second logic control signal is at a specified logic state, the second switching module connects the first connecting end to the second connecting end thereof; a second resistive circuit, which has a first connecting end and a second connecting end, wherein the first connecting end is electrically connected to the second connecting end of the second switching module, while the second connecting end is electrically connected to a grounding node; an input buffer, which has an input end and an output end, wherein the input end is connected to receive the third logic control signal from the logic control signal generating module, while the output end is electrically connected to the pad, and which is capable of buffering the received third logic control signal for outputting from the output end thereof when enabled by a triggering output signal from the chip module; and an output buffer, which has an input end and an output end, wherein the input end is electrically connected to the pad, while the output end is used to generate an output signal serving as a mode setting input signal to the electronic circuit unit for setting the chip module to a specific operating mode.