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What is slew rate in fpga?
The slew rate control determines the maximum rate of change of the output signal. In other words, it defines how fast the rise and fall times of the output signal are. This means that switching times are reduced even on low frequency signals as the rise and fall times are set by the technology.
More drive strength means more current capability – means faster charging/discharging of load capacitor. So, resultant slew will be different at the output of a cell [same logic functionality] with different drive strength.
What is output drive strength?
The drive strength of an I/O specifies how much current we can drive and sink while maintaining the minimum Voh and Vol levels. For example: A LVCMOS25_8mA driver can drive and sink a current of 8 mA and still produce output levels (taken from Spartan-6 data sheet)
What is GPIO drive strength?
Drive strength is the current that a GPIO will try to drive. It is usually specified in mA . Specifying a too large value at the system level can cause the CPU to drive too much total current, which can burn it. Specifying a too low value can burn the GPIO itself.
What’s the difference between slew rate and drive strength?
The slew control parameter (QUIETIO, SLOW, FAST) limits the slew of the on-chip drivers. That sets the fastest rate at which the drivers will slew with no output load. Adding capacitance will slow down the slew rate. Driving a capacitor you typically use the equation:
What does slew rate mean on an amplifier?
Slew rate is a large-signal property of amplifiers and drivers, and indicates the rate of change of the output from its lowest possible level to the highest (or the converse). If your slew rate is too slow, then as above your signal may not reach a valid logic level when it needs to.
What happens if your slew rate is too slow?
If your slew rate is too slow, then as above your signal may not reach a valid logic level when it needs to. Slew rate is defintely taken into account by the timing analyzer tools.
What does maximum and minimum mean on a FPGA?
Maximum and minimum values denote the largest and smallest valid current strength setting, respectively, supported by the I/O standard. All user I/Os are used as output or bidirectional pins. Current strength choices vary with device family and I/O standards. Not supported in dedicated configuration pins.