SLOS709C June 2011 – December 2022 DRV8662
PRODUCTION DATA
When using a PWM input, a low-pass filter is required. The primary parameters for determining the input filter are the PWM input frequency and sample rate. Because haptic waveforms are typically less than 500Hz, the input filter must attenuate frequencies above 500 Hz. For samples rates above 20 kHz, a simple first-order RC filter is recommended; however, for sample rates much lower (such as 8 kHz), a first-order filter may not sufficiently attenuate the high-frequency content. Thus, for lower sampling rates, a second-order RC filter may be required. The DRV8662EVM User's Guide contains example filter configurations for both first-order and second-order filters. The DRV8662EVM default configuration uses a second-order, differential filter, but it can be replaced by a first-order, single-ended or differential filter.
Apply these criteria to select an input filter: