Analog Devices Inc./Maxim Integrated

The LTC2935 ultra-low power voltage monitor provides system initialization, power-fail warning and reset generation functions. Low quiescent current (500nA typical) makes the LTC2935 an ideal choice for battery-operated applications.Three binary threshold-select inputs configure one of eight integrated reset thresholds, ranging from 1.6V to 3.45V in pre-determined increments. Early warning of an impending low voltage condition is provided at the powerfail output (PFO), whose threshold is above the configured reset threshold. Supervisory circuits monitor VCCand pull RST low when VCCdrops below the configured reset threshold. When VCCis rising from an under-threshold condition, an internal reset timer is started after exceeding the reset threshold by 5%. A 200ms reset timeout delays the return of the RST output to a high state. A pushbutton switch connected to the MR input is typically used to force a manual reset. Outputs RST and PFO are available with open-drain (LTC2935-1/LTC2935-3) or active pull-up (LTC2935-2/LTC2935-4) circuits. Operating temperature range is from –40°C to 85°C.ApplicationsPortable EquipmentBattery-Powered EquipmentSecurity SystemsPoint-of-Sale DevicesWireless Systems

The LTC2938/LTC2939 are configurable supply monitors for systems with up to four or six supply voltages that need watchdog supervision. One of sixteen preset or adjustable voltage monitor combinations can be selected using an external resistive divider connected to the program input. The preset voltage thresholds are accurate to ±1.5% over temperature. The LTC2938 and LTC2939 also feature adjustable inputs with a 0.5V nominal threshold.The reset and watchdog timeout periods are adjustable using external capacitors. Tight voltage threshold accuracy and glitch immunity ensure reliable reset operation without false triggering. TheRSToutput is guaranteed to be in the correct state for VCCdown to 1V. Each status output has a weak internal pull-up and may be externally pulled up to a user-defined voltage.The 80μA supply current makes the LTC2938 and LTC2939 ideal for power conscious systems. The LTC2939 monitors up to six supplies and the LTC2938 monitors up to four supplies.ApplicationsDesktop and Notebook ComputersMultivoltage SystemsTelecom EquipmentNetwork ServersAutomotive Control Systems

The LTC2941 measures battery charge state in battery-supplied handheld PC and portable product applications. Its operating range is perfectly suited for single-cell Li-Ion batteries. A precision coulomb counter integrates current through a sense resistor between the battery’s positive terminal and the load or charger. The measured charge is stored in internal registers. An SMBus/I2C interface accesses and configures the device.The LTC2941 features programmable high and low thresholds for accumulated charge. If a threshold is exceeded, the device communicates an alert using either the SMBus alert protocol or by setting a flag in the internal status register.The LTC2941 requires only a single low value external sense resistor to set the current range.Integrated Sense ResistorLTC2941NoLTC2941-1YesApplicationsLow Power Handheld ProductsCellular PhonesMP3 PlayerCamerasGPS

The LTC2941-1 measures battery charge state in battery-powered handheld PC and portable product applications. Its operating range is perfectly suited for single cell Li-Ion batteries. A precision coulomb counter integrates current through an internal sense resistor between the battery’s positive terminal and the load or charger. The measured charge is stored in internal registers. An SMBus/I2C interface accesses and configures the device.The LTC2941-1 features programmable high and low thresholds for accumulated charge. If a threshold is exceeded, the device communicates an alert using either the SMBus alert protocol or by setting a flag in the internal status register.Integrated Sense ResistorLTC2941NoLTC2941-1YesApplicationsLow Power Handheld ProductsCellular PhonesMP3 PlayerCamerasGPS

The LTC2942 measures battery charge state, battery voltage and chip temperature in handheld PC and portable product applications. Its operating range is perfectly suited for single-cell Li-Ion batteries. A precision coulomb counter integrates current through a sense resistor between the battery’s positive terminal and the load or charger. Battery voltage and on-chip temperature are measured with an internal 14-bit No Latency ΔΣ™ADC. The three measured quantities (charge, voltage and temperature) are stored in internal registers accessible via the on-board SMBus/I2C interface.The LTC2942 features programmable high and low thresholds for all three measured quantities. If a programmed threshold is exceeded, the device communicates an alert using either the SMBus alert protocol or by setting a flag in the internal status register.The LTC2942 requires only a single low value sense resistor to set the measured current range.Integrated Sense ResistorLTC2942NoLTC2942-1YesApplicationsLow Power Handheld ProductsCellular PhonesMP3 PlayersCamerasGPS

The LTC2942-1 measures battery charge state, battery voltage and chip temperature in handheld PC and portable product applications. Its operating range is perfectly suited for single cell Li-Ion batteries. A precision coulomb counter integrates current through an internal sense resistor between the battery’s positive terminal and the load or charger. Battery voltage and on-chip temperature are measured with an internal 14-bit No Latency ΔΣ™ADC. The three measured quantities (charge, voltage and temperature) are stored in internal registers accessible via the onboard SMBus/I2C interface.The LTC2942-1 features programmable high and low thresholds for all three measured quantities. If a programmed threshold is exceeded, the device communicates an alert using either the SMBus alert protocol or by setting a flag in the internal status register.Integrated Sense ResistorLTC2942NoLTC2942-1YesApplicationsLow Power Handheld ProductsCellular PhonesMP3 PlayersCamerasGPS