HZ to V 2 Click is a device that can convert input frequency of the signal with virtually any wave shape to a DC voltage output, with a level proportional to the input frequency. It features a specialized IC labeled as VFC32KU, which has a good linear response and temperature stability. By applying a signal with the frequency up to 120kHz on its input, the Click board™ will generate a DC voltage up to 3.3V. The IC is supplied by a dual-voltage boost DC/DC converter IC, which provides the power supply of ±15V, required for the VFC32KU IC operation.
These features allow HZ to V 2 Click to be used in various frequency to voltage applications: in instrumentation, industrial, and automation markets. It is well suited for use in A/D conversion, long-term integration, frequency to voltage conversion, RPM measurement, capacitance measurement, and similar applications which can benefit from an accurate and reliable frequency to voltage conversion. Its function can be complemented by the V to Hz 2 Click, which does the opposite type of conversion: DC voltage to frequency. This can be utilized to build an FM modulator/demodulator application, for example.
The main component of Hz to V 2 Click is the VFC32KU, a voltage-to-frequency and frequency-to-voltage converter from Texas Instruments. It accepts a signal with the frequency within a range between 200Hz and 120kHz on the input and generates DC voltage with the level corresponding to the input frequency, ranging from 0V to 10V, with a highly linear response. The output DC voltage level is further scaled down by the voltage divider on the VFC32KU output, in order to achieve levels acceptable by the MCU. This makes the DC voltage output suitable for sampling, or further processing by the host MCU.
The input signal within the specified frequency range can be applied to either the PWM pin of the mikroBUS™ labeled as FIN on this Click board™ or to the external signal input terminal labeled as FEXT. This signal is AC coupled by a 1nF capacitor, meaning that no DC component will be affecting the connected source. The signal input source can be selected by the onboard switch, labeled as INPUT SEL. A DC voltage output ranging up to 3.3V is available both on the AN pin of the mikroBUS™ labeled as the VO, and the output terminal - labeled as the VOUT on this Click board™.
An onboard high-precision OFFSET potentiometer is used to fine-tune the output of the Click board™. It can be calibrated by using the offset potentiometer, by introducing a signal of a known frequency to either FEXT input terminal or the PWM input pin. An offset trimming procedure should be executed before the first use of the Click board™, since even slight variations in the components tolerances could affect the value at the output. It is recommended to correct the offset after longer time intervals, to compensate for the aging of the passive components on the Click board™.
The VFC32KU IC requires a dual power supply with ±15V. Therefore, this Click board™ utilizes another IC in order to provide the required voltages. It uses the TPS65131, a positive and negative output DC/DC Converter IC, also from Texas Instruments. This DC/DC converter has already been used in Boost-INV 2 Click, so it was tested "on the field" for this purpose. Providing well-stabilized output with the plenty of power headroom, it is a perfect solution for the HZ to V 2 Click, also.
To enable the conversion circuitry, the EN pin of the TPS65131 boost converter should be pulled to a HIGH logic level. This will activate the boost converter and provide the required power for the VFC32KU IC. This pin is routed to the mikroBUS™ CS pin and it is labeled as EN.
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