Semiconductor integrated circuit and communication device for logic input-state control during and following power-up

摘要

The present invention provides a semiconductor integrated circuit device and a communication device incorporating same. Two MOS (strong and weak) devices are connected to each control input of a transceiver. Both MOS devices are turned on while the supply voltage is ramping from 0V. The strong device remains on for a period of 10-20 microseconds. The strong MOS device pulls the input to a disabled state against external capacitance which is attempting to pull the input to an enabled state. The weak MOS device remains on while pulling the input to a disabled state. The input is pulled to an enabled state when an external source overcomes the weak MOS device. Once the control input is pulled beyond the input voltage threshold to the enabled state, the weak MOS device will be turned off permanently and the input will revert to a standard CMOS input with infinite input resistance.