Circuit monitors quad supply for PCI systems

摘要

Many modern systems operate with multiple power supplies that must meet tight tolerances to accommodate high-end μPs and peripherals. For instance, PCI applications may use as many as four supplies: 5V, 3.3V, and ±12V. The circuit in Figure 1 can monitor all these voltages for an under-voltage condition and can also monitor the three positive voltages for an over-voltage condition. The LTC1536 has a built-in ability to monitor the 3.3 and 5V levels and one adjustable level for under-voltage conditions. The adjustable input of the IC monitors the 12V supply. The LTC1536 also acts as the logic input for the open-drain outputs of the LTC1444 quad comparator.