EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: kakiitek on August 24, 2022, 08:06:41 am
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Hi all,
Is the maximum load capacitance in any way related to the configurable drive strength on output pin?
This is what I understand -
1. As long as the total output capacitance of input pins are below the max capacitance of the output pin, the AC specification of the chip will be valid.
2. When the total output capacitance exceeded the max capacitance of the output pin, we need to check on the delay due to this additional capacitance. For slower speed communication, this should be fine assuming we are operating within the timing specification.
3. Setting a higher drive strength would decrease the rise/fall time.
Question -
Does setting higher drive strength helps to reduce the delay caused by high total load capacitance?
How are these two related or are they related at all?
Thanks.
kakiitek
-
Hi all,
Is the maximum load capacitance in any way related to the configurable drive strength on output pin?
This is what I understand -
1. As long as the total output capacitance of input pins are below the max capacitance of the output pin, the AC specification of the chip will be valid.
2. When the total output capacitance exceeded the max capacitance of the output pin, we need to check on the delay due to this additional capacitance. For slower speed communication, this should be fine assuming we are operating within the timing specification.
3. Setting a higher drive strength would decrease the rise/fall time.
Question -
Does setting higher drive strength helps to reduce the delay caused by high total load capacitance?
How are these two related or are they related at all?
Thanks.
kakiitek
Hi,
That may be true in the general case but i believe it is best to decide this on a case by case basis. That is, for each part you intend to use check that out for that particular part. If you use a different part, check that out separately.
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The rise time will be determined by the available current from the drive and the load capacitance. The load capacitance is the sum of wiring, the input capacitance of the driven pin and the output capcacitance of the driver pin.Driving multiple inputs from one driver will add capcitance. Increased line capacitance draws more power from the driver. Power wasted as heat.
V= 1/c ∫i dt
or i=C dv/dt