The CD803X/CD809X/CD810X supervisory circuits monitor the power supply voltage in microprocessor systems. They provide a reset output during power-up, power-down, and brownout conditions. On power-up, an internal timer holds reset asserted for 240 ms. This holds the microprocessor in a reset state until conditions have stabilized. The reset output remains operational with VCC as low as 1 V. The CD803X and CD809X provide an active low reset

signal ( RESET ), whereas the CD810X provides an active high signal (RESET) output. The CD809X and CD810X have push-pull outputs, whereas the CD803X has an open-drain output, which requires an external pull-up resistor. Seven reset threshold voltage options are available, suitable for monitoring a variety of supply voltages (see Table 3). The reset comparator features built-in glitch immunity, making it immune to fast transients on VCC. The CD803X/CD809X/CD810X consume only 17 μA, making them suitable for low power, portable equipment. The CD803X is available in a 3-lead SC70; the CD809X/CD810X are available in 3-lead SOT-23 and 3-lead SC70 packages.