LM131A

LM131A LM131 LM231A LM231 LM331A LM331 Precision Voltage-to-Frequency Converters December 1994 LM131A LM131 LM231A LM231 LM331A LM331 Precision Voltage-to-Frequency Converters General Description The LM131 LM231 LM331 family of voltage-to-frequency converters are ideally suited for use in simple low-cost circuits for analog-to-digital conversion precision frequencyto-voltage conversion long-term integration linear frequency modulation or demodulation and many other functions The output when used as a voltage-to-frequency converter is a pulse train at a frequency precisely proportional to the applied input voltage Thus it provides all the inherent advantages of the voltage-to-frequency conversion techniques and is easy to apply in all standard voltage-to-frequency converter applications Further the LM131A LM231A LM331A attains a new high level of accuracy versus temperature which could only be attained with expensive voltage-to-frequency modules Additionally the LM131 is ideally suited for use in digital systems at low power supply voltages and can provide low-cost analog-to-digital conversion in microprocessor-controlled systems And the frequency from a battery powered voltage-to-frequency converter can be easily channeled through a simple photoisolator to provide isolation against high common mode levels The LM131 LM231 LM331 utilizes a new temperaturecompensated band-gap reference circuit to provide excellent accuracy over the full operating temperature range at power sup...