Getting VDDA/2 reference voltage without opamp.

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Anonymous
Not applicable

 Hello! I'm using C8C3446PVI-076 IC. Are there any ways to get VDDA/2 reference input voltage on pin without using internal opamp?I've used both available opamps in my design and can't use another one for reference voltage. Are thre eny other solutions rather than making external voltage reference for 3.3/2 with stabilitron? Thanks in advance.

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HeLi_263931
Level 8
Level 8
100 solutions authored 50 solutions authored 25 solutions authored

Just use a Vref component. Note that it has a high internal impedance, so you might probalby need an external OpAmp. You could also use a VDAC, but it has the same impedance problem.

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

Since you are probably using a stabilized VDD it is very easy to derive a VDD/2 with a resistor network. Is there any reason why you do not use that for reference?

   

 

   

Bob

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Anonymous
Not applicable

 Unfortunately, using simple resistor divider won't work :(. The voltage on it drops to 0.6-0.8V when I'm trying to use it as Vref. I'm trying to implement AN60594 (but for higher frequencies), but CY8C34 has only two opamps available.

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ETRO_SSN583
Level 9
Level 9
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 If you can burn power scale the absolute value of the external R's in the

   

divider down to function more as a V source. 

   

 

   

Or  can you mux one of the OpAmps and Ref from one measurement

   

to another, eg. double duty the HW needed ? 

   

 

   

Regards, Dana.

   

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

This -

   

 

   

Or  can you mux one of the OpAmps and Ref from one measurement

   

to another, eg. double duty the HW needed ?

   

 

   

should have been stated as this -

   

 

   

Or  can you mux one of the OpAmps and Ref from one measurement

   

to another, eg. double duty the HW used ?

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