LM231DRG

The LM231/LM331 series voltage-to-frequency converters are ideal for implementing simple, low-cost circuits for A/D conversion, precision frequency-to-voltage conversion, long-term integration, linear frequency modulation or demodulation, and many other functions. When used as a voltage-to-frequency converter, the output is a pulse train whose frequency is precisely proportional to the applied input voltage. This provides all the inherent advantages of voltage-to-frequency conversion technology and is easy to implement in all standard V/F converter applications. Furthermore, the LM231A/LM331A achieves a new level of accuracy over temperature that was previously only attainable with expensive V/F modules. In addition, the LM231/331 is well suited for use in digital systems with low supply voltages and provides low-cost A/D conversion in microprocessor-controlled systems. Moreover, the frequency output from a battery-powered V/F converter can easily be transmitted through a simple optoisolator to provide isolation against high common-mode levels. The LM231/LM331 employs a new temperature-compensated bandgap reference circuit that delivers excellent accuracy over the entire operating temperature range at supply voltages as low as 4.0V. Its precision timer circuit features low bias current while maintaining the fast response required for 100kHz V/F conversion. The output is capable of driving 3 TTL loads or high-voltage outputs up to 40V, with short-circuit protection against VCC.

Key features

• Guaranteed maximum linearity 0.01%
• Improved performance for existing voltage-to-frequency conversion applications
• Split or single-supply operation
• Single 5V supply compatible
• Pulse output compatible with all logic families
• Excellent temperature stability: ±50 ppm/°C maximum
• Low power consumption: 15 mW typical at 5V
• Wide dynamic range: 100 dB minimum at 10 kHz full-scale frequency
• Wide full-scale frequency range: 1 Hz to 100 kHz
• Low cost