LTC2900/LTC2901/LTC2902 are quad supply monitors that simultaneously monitor four supply voltages with ± 1.5% threshold accuracy and include a watchdog function and selectable supply tolerance. The ICs allow for one of 16 user-selectable combinations of 5 V, 3.3 V, 3 V, 2.5 V, 1.8 V, 1.5 V, and ± adjustable voltage monitor combinations with a simple external resistor divider on the program pin. This one-pin programming eliminates the need to qualify, source and stock different part numbers for different combinations of supply voltages. Additionally, the reset and watchdog times are user adjustable with external capacitors. On the LTC2901 and LTC2902, all four voltage comparator outputs are connected to separate pins for individual supply monitoring. The LTC2902 gives additional degrees of freedom by offering selectable supply tolerances of 5%, 7.5%, 10%, and 12.5% below the nominal operating voltage. The LTC2900 is offered in a 10-lead MSOP package while the LTC2901 and LTC2902 are available in 16-lead narrow SSOP packages.