While optimized for 40kHz operation, the TS8000 can be evaluated over wider ultrasonic input frequency ranges. You adjust the internal bandpass filter center frequency with your system microcontroller by setting the bottom 7 bits of the configuration register. For a nominal TS8000 device the default setting (0101100b/ 44d) yields a center frequency of ~40kHz. The default center frequency varies device to device and must be calibrated in system to an accurate 40kHz by adjusting the 7 configuration bits (see data sheet for calibration process).
A nominal TS8000 may be adjusted for a wider center frequency range of 25kHz to 65kHz using the same configuration bits and similar calibration process. For 40kHz and below the device can be calibrated in increments of < 1kHz. The increment steps gradually increase to > 1kHz as the center frequency is calibrated from 40kHz toward 65kHz.
During the bandpass filter calibration process the TS8000 generates a DATA pulse that is measured by the system microcontroller. For a 40kHz center frequency the target DATA pulse width is 75us. For other center frequencies the target DATA pulse width should be:
tpw = 3 x (1/fc)
where fc is the desired center frequency (in Hz) and
tpw is the target pulse width (in seconds)
All TS8000 devices can be calibrated to the specified 40kHz center frequency characteristics. Some devices will not be configurable much higher than 40kHz and some devices will not be configurable much lower than 40kHz. Operation outside the specified 40kHz center frequency is recommended for evaluation purposes only and is not guaranteed for volume system production. Contact Triad Semiconductor sales for your specific Ultrasonic-to-Digital Converter requirements.