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LM231: best part to replace AD7740

Part Number: LM231
Other Parts Discussed in Thread: LM331

Hi,

my customer is using AD7740 for voltage to frequency converter.

I wonder if LM231 is the best to promote against AD7740? It seems that our temperature range is narrower.

  • Hi Howard,

    The LM231/LM331 is the only TI V-to-F converter that is designed to operate directly from a low voltage, 5 V supply (4 V minimum). Therefore, it the one option for low voltage applications that the AD7440 might be used in.

    The AD7440 K grade temperature range, according to the datasheet is guaranteed from 0°C to 85°C. It is –40°C to +105°C for the automotive grade device. The LM231 datasheet Operating Ambient temperature is specified as −25 Min, +85 °C Max, in the Recommended Operating Temperature Table 7.3. The AD7440 electrical tables specify the parameters with TMIN to TMAX. While the LM231 Electrical Characteristics table specifies TA = 25°C, unless otherwise specified. Many of the LM231 specifications are specified for TMIN ≤ TA ≤ TMAX.

    The choice that the customer makes comes down to which electrical parameters are most important over temperature in the application, and of course cost.

    Regards, Thomas

    Precision Amplifiers Applications Engineering