Feature description
VFC32 voltage to inverter provides operation up to 500kHz
The output frequency is precisely proportional to its ±input voltage. The digital open collector frequency ± outputs are compatible with all common logic families. Excellent linearity: 0.01% max at 10KHz, 0.05% max at 100KHz
The integrated input feature gives the VFC32 good noise immunity and low nonlinearity. V/F or F/V conversion to monotonic full-scale output frequency by external -NAL capacitors and resistors is available over a wide range of voltage or current input. The VFC32 can also be configured as a frequency-to-voltage converter.
application
VFC32 with 14-pin plastic impregnation, SO-14
Surface mount, metal to -100 package. Commercial, industrial and military temperature range models integrated a/d converter serial frequency output isolated data transfer available.
FM analog signal modem motor speed control tachometer

PIN CONFIGURATION ESD SENSITIVITY This integrated circuit can be damaged by electrostatic discharge. Burr Brown recommends taking proper precautions when handling all integrated circuits. Failure to follow proper operation and installation procedures may result in damage.

Basic hookup diagram for frequency-to-voltage conversion for application information. r Sets the input voltage range. For a 10V full-scale input, a 40KΩ input resistor is recommended. Other input voltage ranges can be achieved by changing the value of r.
R should be of metal film type for good stability. Manufacturing tolerances can vary the output frequency by approximately ±10%. The full-scale output frequency can be adjusted by adjusting the value of r. The full-scale output frequency is determined by C. The values shown in Figure 1 apply to a full-scale output frequency of 10kHz. Values for other full-scale frequencies can be read from Figure 2. Any change in c-tolerance, temperature drift, aging directly affects the output frequency. Ceramic npo or silver mica is a good choice. For full scale frequencies above 200kHz, use a larger capacitance value. The value of the integrating capacitor c does not directly affect the output frequency, but its value must be chosen within a certain range. The values chosen from Figure 2 yield an approximately 2.5vp-p integrator voltage waveform. If the value of c is too low, the output voltage of the integrator will exceed its linear output swing, resulting in a nonlinear response. It is acceptable to use a value of C greater than that shown in Figure 2. The accuracy or temperature stability of c is not critical, as its value does not directly affect the output frequency. However, for best linearity, C should have low leakage and low dielectric absorption. Polycarbonate and other film capacitors are generally fine. Many ceramic types are adequate, but some low-voltage ceramic capacitor types may reduce nonlinearity. Electrolytic type not recommended

Inverter circuit voltage.
The frequency output terminal is an open collector logic output. Pull-up resistors are usually connected to the 5V logic supply to generate standard logic level pulses. However, it can be connected to any power supply up to +V. The output pulse has a constant duration and is positive during one trigger. The current flowing through the open collector output transistor is returned through the common terminal. This terminal should be connected to logic ground.
The frequency to voltage converter is connected to the VFC32 as a frequency-to-voltage converter. Capacitively coupled input networks c, r and r allow standard 5v logic level trigger comparator inputs. The comparator triggers a trigger on the falling edge of the frequency input pulse. The threshold voltage of the comparator is about -0.7V. For frequency input waveforms less than 5V logic levels, the R/R divider can be adjusted to a lower voltage to ensure that the comparator is triggered. The value of 36767c is chosen from Figure 2 based on the full-scale input frequency. c Smooth the output voltage waveform. The larger the value of c, the smaller the output voltage ripple. A smaller value of c allows the output voltage to adapt more quickly to changes in input frequency. Resistor r can be trimmed to achieve the desired output voltage at full scale input frequency.

Gain and bias voltage trimming circuits.

inverter circuit.

V/F converter negative input voltage.