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In theory there is no limit as long as only one device is enabled at any time.
In practise, the limit is the capaitance and delays along the bus connections, there must be adequate time for the signal to reach the far end of the bus and to charge/discharge the capacitance of the bus wiring and all the other drivers.
In theory there is no limit as long as only one device is enabled at any time.
In practise, the limit is the capaitance and delays along the bus connections, there must be adequate time for the signal to reach the far end of the bus and to charge/discharge the capacitance of the bus wiring and all the other drivers.
Thanks a lot. But is there leakage current flow from a device when the device float(high-impendance) to a bus? If yes, I thought maybe those leakage current will reach a level
which could cause bus fight when a large number of device float to a bus.
Yes but unless you have many devices it wouldn't be a problem. The current flowing inbound to the output of a tri-state device would be very small as both the output transistors would be turned off, it wouldn't normally be more an a few uA.
The current flowing in to the inputs of devices on the bus would be more of an issue but as long as you stay within the fan-out rating of the active driver it should reach acceptable logic levels and work OK.
Yes but unless you have many devices it wouldn't be a problem. The current flowing inbound to the output of a tri-state device would be very small as both the output transistors would be turned off, it wouldn't normally be more an a few uA.
The current flowing in to the inputs of devices on the bus would be more of an issue but as long as you stay within the fan-out rating of the active driver it should reach acceptable logic levels and work OK.
current direction goes from a tri state gate to bus, or bus to a tri state gate. It depends on the logic state. Imagine the transisor level circuit of tri state gate and you'll know how the current flows.
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