Portable electronic devices usually include a single 3- or 4-connector jack which can be a stereo headphone jack, a mono headphone jack with microphone input and hook switch, or a stereo headphone jack with microphone/hook-switch combination. Tiny, ultra-low-power comparators like the MAX9060 series can be configured in various ways not only to consume negligible power, but also to provide small, simple, and cost-effective detection of external accessories.