Operating Voltage Range for CapSense Express Devices - KBA82463

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    Question: What is the valid operating voltage range for CapSense Express devices?



    CapSense Express devices are designed to operate at one of three voltage ranges: 2.4—2.9 VDC, 3.1—3.6 VDC, or 4.75—5.25 VDC. CapSense Express devices are not designed to operate continuously over the full range of 5.25—2.4 VDC. This is important to know if your application is battery powered and the operating voltage may gradually decrease as the battery gradually discharges. When the operating voltage is not in the initial operating range the device will still communicate over the I2C bus but the CapSense functionality will not work. Once the device returns to the initial operating range the CapSense functionality will start again but the sensing capability may be impaired unless the system is enabled to recalibrate itself with a reset.

    For best results, ensure that the voltage remains in one of the three operating ranges. Additionally, at 2.4 VDC the CapSense scanning functions operate at a slower frequency and response time decreases by a factor of 4.