Re: slew contron in cmos I/Os circuit
Hi rajesh
The current control of an output I/O cell is very important because of the large parasitic inductances and capacitances of the IC package and the PCB, which causes the voltage swing and affect the GND and all the circuits. In the IC package, the pad size, bonding wire, and configuration of the pins are relavant. These informations are usually provided by the packaging guys. The relavant information can be obtained from the PCB manufacturer. After obtaining all relavant information, the SPICE simulation is to be performed for the output I/O cells so as to determine the W/L of the transistors and meet the tolerance of the swing. There are many types of I/O cells already developed and used, which are organized in more than one stage for the effective control of the output currents.
Bye~~