Power Supply Supervisor ICs Handle Power-On Reset And More

Overvoltage detection and a built-in crowbar interface are features of the MIC2753 and MIC2754 power supply supervisor ICs. Available in the firm’s IttyBitty (SOT23-5) package, the devices handle power-on reset functions as well as helping to minimize system damage in the event of overvoltage faults. Both ICs contain an overvoltage detector with a separate /HV output that can be connected directly to an overvoltage protection circuit, commonly known as a crowbar circuit. When an overvoltage condition is detected, the output is automatically activated. Each IC also includes an undervoltage monitor with reset output, a manual reset input with internal pull-up for direct connection to a switch, and a pulse generator that delivers 140-ms (minimum) reset signals at power-on and at any time the input voltage falls below the programmed threshold. Reset outputs remain asserted for at least 140 ms after the input returns to normal or after releasing the manual reset. Hysteresis on both overvoltage and undervoltage thresholds prevents erratic operation due to noise.The ICs are identical with the exception of the reset outputs: the MIC2753 features an active-high, push-pull reset output while the MIC2754 features an active-low, push-pull output. Typical supply currents for both devices is 30 µA. Applications for the devices include desktop, workstation and notebook PCs, file servers, embedded controllers, power supplies, and telecommunication systems. Custom threshold voltages are available for high-volume applications.