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LM331: The selection for the voltage-to-Frequency Converter

Part Number: LM331

Hi team,

The customer needs to select a voltage-to-Frequency converter. His requirements are as below:

1. The power supply is 12V.

2. Convert 0~10KHZ to 0~10V.

The customer would like to verify if LM2917-N or LM331 can meet his requirements. If they cannot meet the customer's

requirements, would you recommend a suitable device and send me a TINA circuit? I think the customer needs to use

the double power supply to achieve his application, is my understand correct?

Best Wishes,
Mickey Zhang
Asia Customer Support Center
Texas Instruments

  • Hi team,

    Can anyone help me to support the customer's questions?
  • In reply to Mickey Zhang:

    Hi Mickey,
    Is the customer's application voltage to frequency, in which case they might use the LM331, or frequency to voltage, in which case they'd use the LM2917? These two parts aren't interchangeable.

    Regards,

    Alex Davis

    Precision Amplifier Applications - TI Tucson

  • In reply to Alexander Davis:

    Thanks Mickey and Alex,It's my question,LM331 can also be used for F-to-V converters.You can look LMX31X datasheet,There are related examples on page 15 of this datasheet
  • In reply to Alexander Davis:

    Hi Alex,

    Thanks for your reply. The customer needs F to V. But for the LM331 datasheet, it shows it can achieve F to V on page 15.

    Would you explain this?

    For the above customer's requirements, can LM2917 or LM331 be suitable ?
  • Hi Mickey,

    When I review all of TI's VFC products the LM331 is the best suited to meet the requirements you listed. Be sure to observe the input voltage polarity when applying the LM331 in either the datasheet 9.2.1 Basic V-F Converter circuit (0 to 10 V), or 9.2.2 Precision V-F Converter circuit (-10 V to 0 V).

    We do not have a TINA model for the LM331.

    Regards, Thomas

    Precision Amplifiers Applications

  • In reply to Thomas Kuehl:

    Hi:Thomas:

              Maybe you don't understand my quesiton,I  need frequency to voltage converter,not voltage-to- frequency converter

     My requirements are as below:

    1. The power supply is 12V.

    2. Convert 0~10KHZ frequency signal to 0~10V.analog signal;

    I would like to verify if LM2917-N or LM331 can meet his requirements.

  • In reply to liu Qingfu:

    Hello Liu,

    The original post was regarding a voltage-to-frequency conversion and that is what I was responding to. Sorry for the confusion.

    When I examine the datasheets for the LM331 and LM2907 it is clear that each one may be employed as a frequency-to-voltage converter despite their different designs. The LM331 datasheet circuit, Figure 18, "Simple Frequency-to-Voltage Converter" should meet your requirements. I am a bit concerned if it will be able to provide a 10 V maximum output with a 12 V supply. The datasheet doesn't provide details about how close internal nodes can swing to the supply limits so that might be an issue.

    The LM2907 is useable as an F-V converter is well and eliminates the need for a differentiator at the input as required by an LM331 solution. Again, there might be an issue at the maximum output voltage regarding the internal node swing limits with a 12 V supply. You could try the 12 V supply and see if the performance meets your requirements. If not, you would have to increase Vcc.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

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