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Adventurer
Adventurer
7,502 Views
Registered: ‎02-11-2014

Temperature sensorLM35 output to spartan3E board

Hi,

Can we connect the output of LM35( attached fig vout) directly to J7 connector VinA or VinB pin of Spartan3E? While testing the output of Lm35 is varying from about 260mv to 285 mv. 

 

thanks

kathy

LM35-output.JPG
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6 Replies
Xilinx Employee
Xilinx Employee
7,497 Views
Registered: ‎07-31-2012

Re: Temperature sensorLM35 output to spartan3E board

Hi,

 

What is the package of the device? Is the J7 pin a VCCO input?

 

In that case you need to check the Device datasheet and search for the recommended operating voltage and see if this voltage is in range -  However the voltage oscillation is not recommended and the power supply is expected to be stable.

 

Thanks,
Anirudh

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Xilinx Employee
Xilinx Employee
7,483 Views
Registered: ‎07-23-2012

Re: Temperature sensorLM35 output to spartan3E board

Kathy,

 

It looks like you are refering to VINA & VINB of ADC in SPartan 3E starter kit.

 

The allowable voltage range of these pins is given in table 10-2 of http://www.xilinx.com/support/documentation/boards_and_kits/ug230.pdf

 

Regards,

Krishna 

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Adventurer
Adventurer
7,473 Views
Registered: ‎02-11-2014

Re: Temperature sensorLM35 output to spartan3E board

Hi Krishna,

Yes, I am taking about VINA and VINB input toAnalog circuiary in Spartan 3E. Thank you, I went throught ug230 guide. As per the guide the minimum input voltage to preamplifier is 0.4V, is it?   My analog voltage varying from 260mv to 285 mv, do  I need to amplify my signal before giving to preamplifier,I am right? 

thanks

kathy

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Xilinx Employee
Xilinx Employee
7,469 Views
Registered: ‎07-23-2012

Re: Temperature sensorLM35 output to spartan3E board

Hi,

Since the minimum allowed voltage for VINA/VINB is 0.4V, you may need to amplify your signal.

Regards,
Krishna
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Adventurer
Adventurer
7,466 Views
Registered: ‎02-11-2014

Re: Temperature sensorLM35 output to spartan3E board

Thanks krishna, let me try it.

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Adventurer
Adventurer
7,421 Views
Registered: ‎02-11-2014

Re: Temperature sensorLM35 output to spartan3E board

Hi 

In the spartan3e boards with build in ADC circuit  and with gain of-1 and Vin as 1V, then ouput will be 4259 as per equation ; D[13:0] =Gain x((Vin-1.65V)/1.25V )X 8192. I am getting this result, but how can I retrieve back my orginal input voltage (1V)? 

Thank you

kathy

 

 

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