OpAmp pins

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HuEl_264296
Level 5
Level 5
First like given 25 sign-ins First solution authored

Hi,

   

 

   

There are several uncomitted OpAmps on some PSoC3s

   

The outputs seem to be connected to specific pins. Does this mean I can't route them to other pins? Does it mean I can't route them to other internal devices? E.G. ADC.

   

The inputs also seem to be connected to specific pins, but according to the TRM, there seems to be more options for connecting them to other buses. Is there some advantage to using those specific pins rather than other pins?

   

Is there any advantage to using those OpAmps rather than the ones in the SC/CT blocks?

   

 

   

Hugo

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1 Solution
ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

These ap notes may help -

   

 

   

http://www.cypress.com/?rID=39974

   

http://www.cypress.com/?rID=57571

   

 

   

Related Application Notes

   


  AN54181 – Getting Started with PSoC 3
  AN60631 – PSoC 3 Clocking Resources
  AN58304 – PSoC 3 and PSoC 5LP - Pin Selection for
Analog Designs
  AN58827 – Internal Routing Considerations for
PSoC 3 and PSoC 5LP Analog Designs
  AN54460 – Interrupt Handling in PSoC 3
  AN60580 – SIO Tips and Tricks in PSoC 3 and
PSoC 5LP
  AN66083 – Using Sleep and Hibernate Modes in
PSoC 3
  AN52705 – PSoC 3 and PSoC 5LP - Getting Started
with DMA

   

 

   

Regards, Dana.

View solution in original post

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4 Replies
ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

These ap notes may help -

   

 

   

http://www.cypress.com/?rID=39974

   

http://www.cypress.com/?rID=57571

   

 

   

Related Application Notes

   


  AN54181 – Getting Started with PSoC 3
  AN60631 – PSoC 3 Clocking Resources
  AN58304 – PSoC 3 and PSoC 5LP - Pin Selection for
Analog Designs
  AN58827 – Internal Routing Considerations for
PSoC 3 and PSoC 5LP Analog Designs
  AN54460 – Interrupt Handling in PSoC 3
  AN60580 – SIO Tips and Tricks in PSoC 3 and
PSoC 5LP
  AN66083 – Using Sleep and Hibernate Modes in
PSoC 3
  AN52705 – PSoC 3 and PSoC 5LP - Getting Started
with DMA

   

 

   

Regards, Dana.

0 Likes
Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

Whenever you use one of the opamps its dedicated pins will be in use and cannot be used by another component. The router is able to connect that opamp to another pin when required, but the dedicated pins will still be in use. So the route is "hopping" from the dedicated pin to the target.

   

This was used to have low-impandence connections for some of the internal devices to the outside.

   

 

   

Bob

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ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

Modificatiuon to what Bob said. Just the OpAmp output pin becomes dedicated,

   

not its inputs.

   

 

   

   

Opamp Pin Selection

       

   

 

   

The opamps are connected to the GPIOs in such a way that they can be used without

   

any internal analog global busses, See Figure 12. If all connections to the opamp are

   

external through the GPIOs, it is a good idea to use the dedicated pins. In many cases,

   

the opamp may be used as a buffer to an internally generated signal, such as a buffer to

   

a VDAC output. In this case the dedicated opamp input pins may be ignored and used for

   

another purpose. After the opamp is enabled, the dedicated output GPIO will always be

   

driven by the output of the opamp. This GPIO is now dedicated to the opamp output and

   

cannot be used for another signal. Even if this signal is only used internally, the dedicated

   

output pin will be driven by the opamp. This guarantees that the resistance between the

   

opamp and GPIO pin is low, about 5 ohms. If you must use a different pin for the output,

   

the dedicated output pin still outputs the signal. If the opamp is not used, it has no affect

   

on the GPIOs directly connected to it. These GPIO pins operate as any of the other GPIOs

   

when the opamp is disabled.  

   

Regards, Dana.

ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

Makes one wonder if the output pin can be over-ridden with a register write.

   

 

   

After all out R in the path of an OpAmp output, its effective Zo becomes divided

   

by loop gain.

   

 

   

Regards, Dana.

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