MIC2779 Voltage Monitor with Adjustable Hysteresis Features General Description Optimized for PDAs, Cellular Telephones, Pagers, The MIC2779 is a voltage monitor that is uniquely and Other Battery-Powered Devices designed to detect two separate voltage thresholds combined with a delay generator and logic. It is Independently Adjustable High- and Low-Voltage designed for monitoring the battery supply of portable Thresholds digital systems, particularly PDAs, pagers, and cellular Internal Logic Prevents Battery Voltage telephones. Fluctuation Chatter High- and low-voltage thresholds can be adjusted High 2% Voltage Threshold Accuracy independently, allowing for wide hysteresis. Voltage Built-In 140 ms (Minimum) Delay Deglitches detection thresholds are accurate to 2%. Output If the battery voltage falls below the low-voltage Extremely Low 1 A Typical Supply Current threshold, the output /RST or RST is asserted and For Applications that Require Open-Drain Output, latched, preventing system operation until the battery is See MIC2778/MIC833 replaced or recharged. Internal logic prevents the Immune to Brief Power Supply Transients output from chattering due to battery recovery or load Available in 5-Lead SOT23 Package removal. The output is asserted for 140 ms (minimum) when a fresh battery is inserted. For applications Applications requiring open-drain output, see MIC2778/MIC833. PDAs The ICs power supply input is separate from the Pagers detector inputs, allowing the MIC2779 to be powered from a downstream supply, such a boost converter. Cordless Phones Supply current is extremely low (1 A, typical), making Consumer Electronics it ideal for portable applications. The MIC2779 is Embedded Controllers supplied in a 5-lead SOT23 package. Personal Electronics Package Types MIC2779H MIC2779L SOT23-5 (M5) SOT23-5 (M5) (Top View) (Top View) LTH GND HTH LTH GND HTH 3 2 1 3 2 1 45 45 RST VDD /RST VDD 2018 Microchip Technology Inc. DS20006116A-page 1MIC2779 Typical Application Circuit Cellular Telephone Battery Monitor V OUT MIC5207-3.0YM5 3.0V OUT IN 470pF MIC2779L Li-Ion 4.7F BYP N Cell VDD EN /RST 1% GND LTH N HTH GND 1% N 1% V = 3.6V BAT(hi) V = 3.1V BAT(lo) Functional Block Diagram V DD V BATT Low-Voltage Detect LTH V LO R Q /RST* One Shot High-Voltage HTH Detect RST* V S Q HI Delay Line 1.24V Bandgap Reference MIC2779 GND * Pinout and polarity vary by device type. See Product Identification System section. DS20006116A-page 2 2018 Microchip Technology Inc.