MIC2778

MIC2778 Micrel MIC2778 Voltage Monitor with Adjustable Hysteresis Preliminary Information General Description The MIC2778 is a voltage monitor—uniquely designed to detect two separate voltage thresholds—combined with a delay generator and logic. It is designed for monitoring the battery supply of portable digital systems, particularly PDAs, pagers, and cellular telephones. High- and low-voltage thresholds can be adjusted independently, allowing for wide hysteresis. Voltage detection thresholds are accurate to 2%. If the battery voltage falls below the low-voltage threshold, the output (RST) is asserted and latched, preventing system operation until the battery is replaced or recharged. Internal logic prevents the output from chattering due to battery recovery or load removal. The output is asserted for 140ms (minimum) when a fresh battery is inserted. For applications not requiring built-in delay, see MIC833. The IC’s power supply input is separate from the detector inputs, allowing the MIC2778 to be powered from a downstream supply, such a boost converter. Supply current is extremely low (1µA, typical), making it ideal for portable applications. A high-precision 1% grade is available. The MIC2778 is supplied in Micrel’s IttyBitty™ 5-lead SOT-23-5 package. Features Optimized for PDAs, cellular telephones, pagers, and other battery-powered devices Independently adjustable high- and low-voltage thresholds Internal logic prevents battery-voltage-fluctuation chatter H...