Supervisory circuits reduce power needs in mobile applications

New microprocessor supervisory circuits for monitoring under-voltage conditions in hand-held industrial instruments, telecommunications devices, and other portable applications are now available. The ADM6326, ADM6328, ADM6346, and ADM6348 supervisory circuits feature an ultra-low 500-nA supply current that can extend the battery life of mobile devices. The new circuits provide a low-power option for precise monitoring of DSP, ASIC, FPGA, and other processor power supplies to detect under-voltage conditions that can lead to system failure.

The supervisory ICs monitor 2.5, 3, 3.3, and 5 V voltage rails. The ADM6326, ADM6328, ADM6346, and ADM6348 provide a reset output during power-up, power-down, and brownout conditions. On power-up, an internal timer holds reset asserted for at least 100 ms, which effectively holds the microprocessor in a reset state until conditions have stabilized.

The ADM6326 and ADM6346 have an active low push-pull reset output. The ADM6328 and ADM6348 have an active low open-drain output, which requires an external pull-up resistor. In addition, 24 reset threshold voltage options are available, in increments between 2.2 and 4.63 V, making these devices suitable for monitoring a variety of supplies.

The new ICs are available in a space-saving, 3-lead SOT-23 package and operate over an extended temperature range of −40° to 85° C. As part of a complete signal chain, the supervisory circuits are compatible with the company's ADP2503 and ADP2504 dc-to-dc converters, ADP2121 switching regulator, and the ADP121 LDO. For more information, visit Analog Devices.

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