Opamp Input and Output Pins and Routing in a PSoC® 3/ PSoC 5LP Design - KBA203632

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Question:

What are the precautions to be taken when handling opamp dedicated pins in a PSoC 3/ PSoC 5LP design?

 

Answer:

All four uncommitted opamps have two dedicated pins, which can be routed to the opamp inputs. However, it does not mean that the opamp has to have its inputs from these input pins only. The opamp inputs can also be rerouted to other pins through the analog routing. 

The opamp outputs, on the other hand, are fixed and dedicated pins in the device. In a 4-opamp device, the pins P0[0], P3[6], P0[1], and P3[7] are dedicated opamp outputs. The output of an opamp always goes to its dedicated pin. 

When the opamp output is routed to a pin other than the dedicated output pin, the dedicated output pin is still going to be connected to the opamp output along with the pin the user has chosen.

Note that when the opamp’s dedicated output pin is not used, it uses the analog routing structure to route the opamp output to a different pin. This would include a few switch resistances and global resistances making the opamp drive strength lower. You should pay particular attention to this factor if your application has limited bandwidth/slew.