The LM231/LM331 family of voltage-to-frequency converters are ideally suited for use in simple low- cost circuits for analog-to-digital conversion， precision frequency-to-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 LM231A/LM331A attain a new high level of accuracy versus temperature which could only be attained with expensive voltage-to-frequency modules。Additionally the LM231/331 are 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 voltageto-frequency converter can be easily channeled through a simple photo isolator to provide isolation against high common mode levels。